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Does the CE Code allow an outdoor dielectric liquid-filled transformer 1m of a door or window of a building?

Posted By Steve Douglas, Friday, January 24, 2014

The general requirements in the Canadian Electrical Code Part I (CE Code) covering clearance of outdoor oil-filled transformers to a building or openings are not new; in fact, the first edition of the CE Code, dated 1927, had the following requirement.

Rule 2003 (b) Oil-filled transformers shall not be installed on a roof or over or near any window, door or other opening into a building. If attached to a wall, both the wall and the means of support shall be of fireproof construction and the transformers shall be separated from the wall by at least 6 inches.

In the 21 editions of the CE Code since the first edition, the requirements have changed 13 times. The most significant changes are in the editions dated 1953, 1958, 1972, 1978, 1986, 1990, 1994, and 2006. In the 1953 edition, Rule 8-044 (3) required oil-filled transformers in immediate proximity of a building to be placed adjacent to blank walls of masonry or concrete. The 1958 edition was the first to include clearance measurements in the form of Table 38.

 


Figure 1.  Table 38

 

In the 1972 edition, in addition to moving the requirements to Section 26, the table was deleted and the rule was completely rewritten.

Rule 26-010 Flammable Oil-Insulated Equipment, Outdoor

(1) Electrical equipment containing liquids that will burn in air, in quantities of more than 10 gallons, and installed outdoors, shall not, except as permitted by Subrule (3), be located within 20 feet of:

a. Any combustible surface of material on a building

b. Any door or window; or

c. Any ventilation inlet or outlet.

(2) The dimension referred to Subrule (1) shall be the shortest line-of-sight distance from the face of the container containing the flammable liquid to the building or part of the building in question.

(3) Notwithstanding the requirements of Subrule (1), the equipment may be installed within 20 feet of a building providing a suitable non-combustible wall or barrier is constructed, in a manner acceptable to the supply authority and the inspection department, between the building and the equipment.

(4) Where electrical equipment containing liquids that will burn in air, in quantities of more than 10 gallons, are installed outdoors they shall:

a. Be inaccessible to unauthorized persons;

b. Not obstruct fire-fighting operations;

c. If installed at ground level, be located on a concrete pad draining away from structures or be in a curbed area filled with coarse crushed stone; and

d. Note have open drains for the disposal of flammable liquid in the proximity of combustible construction or material.

The quantities in Subrules (1) and (4) were increased from 10 gallons to 30 gallons in the 1978 edition, and "a suitable non-combustible wall or barrier is constructed” in Subrule (3) was changed to "a suitable fire-resisting wall or barrier is constructed” in the 1982 edition.

 

Photo 1. Power transformer built to CSA Standard C88.

The 1986 edition has a significant new Subrule (2) added to Rule 26-242.

(2) Liquid-filled pad-mounted distribution transformers shall be installed at least 3 m from any combustible surface or material on a building and shall be installed at least 6 m from any window, door, or ventilation opening on a building.

This change is significant as the measurement is now from a surface or material not the wall. This means the wall can be of combustible construction provided the surface is non-combustible. The other more significant change is that the code now recognises the difference between power and distribution transformers. Rule 26-014 deals with power transformers and other dielectric liquid-filled equipment, and Rule 26-242 addresses distribution transformers. A power transformer is a liquid-filled transformer built to CSA Standard C88 Power transformer and reactor. A distribution transformer is a liquid-filled transformer rated not more than 3000kVA and not more than 34.5kV built to CSA Standards C2.1 Single-phase and three-phase liquid-filled distribution transformers; C2.2 Pole-mounted, single-phase distribution transformers for electric utilities; C227.3 Low-profile, single-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors; C227.4 Three-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors; or C227.5 Three-phase live-front pad-mounted distribution transformers. With that said, not all transformers rated up to 3000KVA and up to 34.5kV are distribution transformers, as the scope CSA Standard C88 covers all liquid-filled transformer sizes and voltages. All transformers built to CSA Standard C88 are required to meet clearances in Rule 26-014.

Changes in the 1990 and 1994 editions recognised the practice of installing a barrier or wall between the transformer and the building to reduce the clearance requirements, provided the surface on the wall or barrier is non-combustible.

A new Subrule (3) was added to Rule 26-242 in the 2002 edition that was amalgamated with Subrule (2) in the 2006 edition to read:

(2) Dielectric liquid-filled pad-mounted distribution transformers shall be installed at least 3 m from any combustible surface or material on a building and at least 6 m from any window, door, or ventilation inlet or outlet on a building, except where

(a) a wall or barrier with non-combustible surfaces or material is constructed between the transformer and any door, window, ventilation opening, or combustible surface; or

(b) the transformer is protected by an internal current-limiting fuse and equipped with a pressure relief device, with working spaces around the transformer of at least 3 m on the access side and on all other sides:

(i) 1 m for three-phase transformers; and

(ii) 0.6 m for single-phase transformers.

Item (b) of this new Subrule (2) allows reduced clearances where the distribution transformer is protected by an internal current-limiting fuse and equipped with a pressure relief device. CSA Standards C227.3, and C227.4 require internal current-limiting fuses, and a pressure relief device on all pad-mounted tramper-resistant distribution transformers built to these standards. Internal current-limiting fuses, and a pressure relief device are optional for transformers built to CSA Standards C2.1, C2.2, and C227.5.


 Photo 2.  A three-phase liquid-filled distribution transformer built to CSA Standard C2.1

 

Photo 3.  Pole-mounted, single-phase distribution transformer for electric utilities  covered by CSA Standard C2.2

 

Photo 4. A low-profile, single-phase, pad-mounted distribution transformer built to CSA Standard C227.3


Rules 26-014 and 26-242 have remained unchanged from the 2006 edition of the CE Code.

 

26-014 Dielectric liquid-filled equipment — Outdoors (see Appendix B)

(1) Except as permitted by Subrule (3), dielectric liquid-filled electrical equipment containing more than 46 L in one tank, or 137 L in a group of tanks, and installed outdoors shall not be located within 6 m of

(a) any combustible surfaces or material on a building;

(b) any door or window; or

(c) any ventilation inlet or outlet.

(2) The dimension referred to in Subrule (1) shall be the shortest line-of-sight distance from the face of the container containing the liquid to the building or part of the building in question.

(3) Notwithstanding the requirements of Subrule (1), the equipment shall be permitted to be installed within 6 m of any item listed in Subrule (1)(a), (b), and (c), provided that a wall or barrier with non-combustible surfaces or material is constructed between the equipment and that item.

Appendix B Rule 26-014(3)

The normal enclosure for the equipment is not to be considered as the barrier referred to in this Subrule.

(4) Where dielectric liquid-filled electrical equipment containing more than 46 L in one tank, or 137 L in a group of tanks, is installed outdoors it shall

(a) be inaccessible to unauthorized persons;

(b) not obstruct firefighting operations;

(c) if installed at ground level, be located on a concrete pad draining away from structures or be in a curbed area filled with coarse crushed stone; and

(d) not have open drains for the disposal of the liquid in the proximity of combustible construction or materials.

26-242 Outdoor transformer installations

(1) Except as permitted by Subrule (2), where transformers, including their conductors and control and protective equipment, are installed outdoors, they shall

(a) be installed in accordance with Rule 26-014 if they are dielectric liquid-filled;

(b) have the bottom of their platform not less than 3.6 m above ground if they are isolated by elevation;

(c) have the entire installation surrounded by a suitable fence in accordance with Rules 26-300 to 26-324 if they are not isolated by elevation or not housed in suitable enclosures; and

(d) have conspicuously posted, suitable warning signs indicating the highest voltage employed except where there is no exposed live part.

(2) Dielectric liquid-filled pad-mounted distribution transformers shall be installed at least 3 m from any combustible surface or material on a building and at least 6 m from any window, door, or ventilation inlet or outlet on a building, except where

(a) a wall or barrier with non-combustible surfaces or material is constructed between the transformer and any door, window, ventilation opening, or combustible surface; or

(b) the transformer is protected by an internal current-limiting fuse and equipped with a pressure relief device, with working spaces around the transformer of at least 3 m on the access side and on all other sides:

(i) 1 m for three-phase transformers; and

(ii) 0.6 m for single-phase transformers.

 

Photo 5. A three-phase, pad-mounted distribution transformer built to CSA Standard C227.4

 

Photo 6. Three-phase live-front pad-mounted distribution transformer built to CSA Standard C227.5 close-coupled with a high voltage switch 

 

Photo 7.   A non-combustible  surface installed on a barrier between a distribution transformer and the back door of a restaurant. 

To answer the original question, the CE Code does allow an outdoor dielectric liquid-filled transformer 1m of a door or window of a building provided the transformer is a distribution transformer with an internal current-limiting fuse and equipped with a pressure relief device.


Read more by Steve Douglas

Tags:  Featured  January-February 2014 

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UL’s New Enhanced Certification Mark

Posted By Underwriters Laboratories, Friday, January 24, 2014

Question 

I have seen that UL has developed a new certification mark. Can you tell me more about it? Are the current Listing and Classification marks still good?

Answer 

Earlier this year, UL launched an enhanced version of its certification Mark. Even with the introduction of the enhanced Mark, all current UL Listing and Classification Marks remain valid and should continue to be accepted as an indication of certification.

 

For over 100 years, designers, architects and code authorities have relied on UL’s Marks to determine code compliance. But, products in today’s environment must meet a diverse spectrum of certification and compliance requirements. In response to evolving customer needs, UL introduced an enhanced version of our Certification Mark that manufacturers have the option of using in place of our traditional Listing and Classification Marks.

One important change you will note in the enhanced Mark is the use of the term "Certified.” Certified is a general term encompassing Listed and Classified and complies with the definition of "listed” in all model codes. It’s also a term that is more easily understood by the marketplace.

The enhanced UL Mark also identifies the attributes that UL has certified about a product. For example, "Safety” indicates that a product has been certified in accordance with the applicable safety requirements. "Energy” means that a product has been certified in accordance with the applicable energy efficiency requirements. There are several other attributes that may appear on the enhanced UL Mark, and the enhanced Mark may include more than one attribute to describe the full set of certifications a product has earned.

The enhanced UL Mark includes an ISO (International Standards Organization) country code such as "US” for the United States or "CA” for Canada to identify the country requirements for which the product has been certified.

Another significant feature of the enhanced Mark is the use of a unique identifier (most commonly for products in the built environment, a UL file number). This enables users to easily verify certification information at UL’s Online Certifications Directory. Just go to www.ul.com/database and search by the enhanced Mark identifier using the UL File Number field or Keyword Search ("S123456” in the illustration). That search will send you directly to a product’s certification record, which also includes a link to the product category guide information. This will go a long way to enabling easy verification of the scope of a product’s certification to determine compliance with the Code. If required, a product name or identification will also be on the product near the enhanced Mark to assist in verifying the certification product category in UL’s White Book.

An example of an enhanced UL Mark is shown in the accompanying illustration, and details on the Mark are included in product category guide information in UL’s Online Certifications Directory and will appear in the 2014 UL White Book.

UL expects the transition to the enhanced Mark to happen over time, so you may not see it in the immediate future. For more information on this important development, please go to www.ul.com/markshub > Resources. Access to the Marks Hub is free and open to all regulators, but registration to use it is required.

Tags:  Featured  January-February 2014 

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Marking Available Fault Current

Posted By Thomas A. Domitrovich, Friday, January 24, 2014

When standing in front of a line-up of switchgear, panelboards or switchboards you may be amazed at how many labels you see. These labels are there for a reason and can be very helpful if you just take the time to understand them. Today we’re going to talk about NECSection 110.24, "Available Fault Current,” and a few other associated sections to understand this requirement and the various ways it impacts safety.

 

Photo 1.   Free software is available for calculating available fault current to help meet Section 110.24 requirements.

Available Fault Current

Available fault current, to many, simply means maximum available fault current because of the fact that we have always had to ensure equipment was rated properly and could handle the interruption or could withstand the maximum the system could provide. It has been a requirement for years in the NEC. In my copy of NEC 1940 for example, Section 1114, "Interrupting Capacity,” states, "Devices intended to break current shall have an interrupting capacity sufficient for the voltage employed and for the current which must be interrupted.” I’m sure this requirement goes much further back than 1940. We know this requirement today as 110.9, "Interrupting Rating,” of the NEC and even as recent as NEC 2014, this section continues to receive attention. NEC 2014 language for 110.9 reads as follows:

"Equipment intended to interrupt current at fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that is available at the line terminals of the equipment.

"Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that must be interrupted.”

The second paragraph above was added as part of NEC1978. The substantiation for the proposal that was made and accepted by the panel noted that "The concept of ‘at fault levels’ removes from this consideration simple disconnect switches which may break charging or magnetizing current. ‘System’ voltage may be different from ‘employed.’ ‘Available current’ is a more adequate definition than ‘that must be interrupted.’ The difference between a fault interrupter and a simple disconnect switch needs bringing out in this section.” Section 110.9 has seen changes ever since to become ultimately what we know in NEC 2014 as that depicted above.

Another important equipment rating involving available fault current is an equipment short-circuit current rating. While an interrupting rating applies to the ability of an overcurrent device to safely open an overcurrent, or the ability of, for example, a motor controller to open locked rotor current, a short-circuit current rating applies to the ability of electrical equipment to safely carry short-circuit current, not openshort-circuit current. NEC 110.10, "Circuit Impedance, Short-Circuit Current Ratings, and Other Characteristics” requires that equipment have a short-circuit current rating that is equal to or greater than the maximum available short-circuit current.

 

Photo 2.  There are many labels that can be found on electrical equipment and they are there for a reason.  Understand these labels and how they relate to the proper application of products.

Available fault current is an important parameter for designers, installers and inspectors to ensure equipment is being applied within its rating. The requirement of labeling the available fault current as part of 110.24 though did more than just elevate the awareness of meeting 110.9 and 110.10 when it was introduced as part of NEC 2011. This section packs a punch when it comes to safety.

Field Marking requirements

There are various sections in the code that require a field marking to be applied to equipment. A marking would have to be field applied and not applied by the manufacturer prior to shipping for various reasons. One example can be found in 450.14, "Disconnect Means,” for transformers. The language in this section states, for transformers other than Class 2 or Class 3 that are required to have a disconnect, where that disconnect is ". . . in a remote location, the disconnecting means shall be lockable, and the location shall be field marked on the transformer.” Due to the installation method, a field marking is required. Other examples in addition to 450.14 of field marking requirements, include the following sections of the NEC

240.86, "Series Ratings”

408.3, "Support and Arrangement of Busbars and Conductors.” 408.3(F), "Switchboard or Panelboard Identification.”

550.33, "Feeder,” 550.33(A) "Feeder Conductors”

Section 110.24, "Available Fault Current”, which was first introduced in NEC 2011, is another example of a field marking requirement that cannot be applied by the manufacturer as the system dictates the available fault current. The field marking language of 110.24 states, "Service equipment in other than dwelling units shall be legibly marked in the field with the maximum available fault current. The field marking(s) shall include the date the fault current calculation was performed and be of sufficient durability to withstand the environment involved

In addition to the available fault current, the requirement here is for the date that the fault current calculation was performed. As far as this author can tell, there are only two other areas in NEC2014 that require a date to be field marked. Those can be found in Article 640 for "Audio Signal Processing, Amplification, and Reproduction Equipment” and in Article 645 which addresses "Information Technology Equipment.” Section 640.6, "Mechanical Execution of Work” item (D), "Installed Audio Distribution Cable Identified for Future Use,” requires cable tags on these future use cables to include the date the cable was identified for future use and the date of intended use. In a similar manner 645.5, "Supply Circuits and Interconnecting Cables,” has item (H), "Installed Supply Circuits and Interconnecting Cables Identified for Future Use,” which requires labeling of these cables with tags that include a date the cable was identified for future use and the date of intended use. Including a date on these labels makes a statement. Including a date on the label required as part of 110.24 does this as well.

The field marking of available fault current raised the awareness of meeting the requirement of 110.9, and including the date raised the awareness that the available fault current can change. Changes in available fault current could be due to changes on the utility side of the equipment and on the customer side of the equipment. Lighting loads and similar will not add to the fault contribution, but those that add motors for example are adding sources of fault current. Major changes in facilities can increase the available fault current. Changes on the utility side of the facility can also increase the available fault current. As an example of when a utility available fault current could change and cause a problem for existing equipment, let’s consider a strip mall of X number of stores that experiences a growth by adding 2X more stores to the existing structure. In this case, if the existing service is used, the utility may have to increase the size of the transformer supplying the entire load. A larger transformer, with the same impedance would translate into higher fault current. This new fault current could put the existing service and all existing electrical equipment at risk of having their ratings exceeded. Good planning ahead of time could avoid problems like this. When the existing labels are updated and inspections proceed, awareness of the problem may be raised.

 

Figure 1.  This is the calculation and label for equipment showing an available fault current of more than 32kA.  The equipment in this case must be rated for an available fault current greater than that marked.   The circuit breaker label shown in Photo 3 would be adequate in this application.

 

Figure 2.   For the same circuit as shown in Figure 1, the transformer in this case was changed having a higher KVA rating and a lower impedance.  The fault current is significantly different.  The circuit breaker label shown in Photo 3 would not be adequate in this application.


110.24 and Arc Flash

There has been a bit of confusion regarding the use of the 110.24-required maximum available fault current marking for arc-flash protection. When first introduced, many in the industry rose to the floor in concern that this number would be used for the calculation of incident energy. Others pointed out the original intent of verifying short-circuit ratings but also noted it could be used with the "Table Method” in NFPA 70E to determine the necessary personal protective equipment. These discussions led to the addition of an Informational Note to 110.24(A) which stated that, "The available fault-current marking(s) addressed in 110.24 is related to required short-circuit current ratings of equipment. NFPA 70E-2012,Standard for Electrical Safety in the Workplace, provides assistance in determining the severity of potential exposure, planning safe work practices, and selecting personal protective equipment.”

The Informational Note clarifies the purpose of the marking, which is to assure that service equipment has the right interrupting ratings and short-circuit current ratings. The second part of this informational note simply says that "NFPA 70E-2012 . . . provides assistance in determining the severity of potential exposure, planning safe work practices and selecting personal protective equipment.” This additional note about 70E is helpful as it directs us to the appropriate place for addressing arc flash safety. So that’s where I went to understand whether or not I can use this label for any activities surrounding safe work practices and arc flash.

What I learned was that the marked maximum available fault current cannot be used in the calculation of incident energy, as an incident energy calculation actually needs the actual available fault current; but this number can be used with the "Table Method” that is a part of NFPA 70E. Using the maximum available fault current in the calculation method could result in a calculation that significantly underestimates or overestimates the incident energy, either of which could result in serious injury or death to the worker if an arc-flash incident occurs. If the calculation results in a significant underestimate, it is quite obvious that the worker might not have "enough” PPE for the arc-flash that could occur. On the other hand, overestimating the incident energy could also be hazardous. My initial thought of this was that overdressing for an arc flash event is a good thing. But as many in the industry who must suit up for these higher energies have pointed out to me, an overestimate of incident energy could result in a worker wearing too much PPE which could result in heat exhaustion or an accident from poor visibility and/or poor dexterity. After donning a 40 Cal suit, you’ll understand as well.

 

Photo 3.  Electrical equipment will be marked with short-circuit interrupting capabilities. This is a circuit breaker label that shows the interrupting capability of the breaker. The maximum available fault current must be less than the interrupting rating of the breaker at the applied voltage. 

The "Table Method” outlined in NFPA 70E does offer one way that these 110.24 labels could be used for arc flash safety. In the 2012 edition of NFPA 70E, Table 130.7(C)(15)(a) can be used to determine the Hazard Risk Category for specific tasks with specific equipment under specific operating conditions. For example, assume that an enclosed 200-ampere molded-case circuit breaker, with a 42,000-ampere interrupting rating, is the service disconnecting means and service overcurrent protective device feeding a main-lug-only 240-volt panelboard immediately next to the enclosed circuit breaker. Assume the task is to remove a bolted cover on the 240-volt panelboard. An energized electrical work permit is obtained after determining that performing the work de-energized would introduce additional or increased risk.

When an incident energy value is not available, the very first part of Table 130.7(C)(15)(a) might be utilized as long as the equipment and operating conditions are met. Those conditions include a maximum available short-circuit (fault) current of 25,000 amperes and a maximum of a 2-cycle clearing time for the class of overcurrent protective device protecting the panelboard (at the 25,000-ampere fault level). In this example, the maximum available fault current is 19,829 amperes. This fault current level addresses the first of the conditions (25,000 amperes or less). Standard thermal magnetic 200-ampere (and less) molded-case circuit breakers, as a class, will have clearing times about ½ cycle at their interrupting rating, so the 2-cycle clearing time requirement is also met. Finally, the working distance is determined to be 18 inches or greater. With all of the specific conditions met, the table can be used to determine that the task would be a Hazard/Risk Category 1. Table 130.7(C)(16) then shows that arc-rated clothing with a minimum arc-rating of 4 cal/cm2 would be required (see Note 3). This would include (1) arc-rated shirt and arc-rated pants (or arc-rated coveralls), (2) arc-rated face shield (See Note 2) or arc-flash suit hood, (3) arc-rated jacket, parka, rainwear, or hard-hat liner, (4) hard hat, (5) Safety glasses or safety goggles, (6) Hearing protection, (7) Heavy duty leather gloves (See Note 1), and (8) Leather work shoes.

 

Photo 4.  IAEI offers materials and training to help educate on such requirements as NEC 110.24 as well as many more — yet one more example of why it is important to be a member of the IAEI.

Closing Remarks

Available fault current is a very important parameter to consider in your design, installation and inspection. There are tools available on the market to help you calculate the available fault current. Leverage your resources and ensure proper labels are installed to ensure products are applied within their listing. With respect to how this maximum available fault current value, marked per 110.24, may or may not be used with respect to arc flash, note that it may not be used to calculate incident energy, but it may be used with the "Table Method” in NFPA 70E.

As always, keep safety at the top of your list and ensure you and those around you live to see another day.


Seeds of Safety

Quite a few editions ago, I included an article about how West Virginia IAEI, under the guidance of Jack Jamison and his team of leaders in safety, work every year to foster continued education of students of electricity through the involvement of the SkillsUSA competition events. SkillsUSA is a national organization for students in trade, industrial, technical and health occupations education (www.skillsusa.org). This organization sponsors a SkillsUSA Championship annual event that recognizes achievements of career and technical education students. Although this past year was not hosted by IAEI, the team is still very much involved with helping students understand the National Electrical Code and other important topics for our industry through the educational events that the West Virginia IAEI provides. Just this past fall saw more than 40 students attend the educational program put on by the West Virginia IAEI. Today I want to tell you about two other leaders from the tri-state area that have a great story to tell.

Mr. Tim Gump has been teaching for more than 15 years and is currently ushering students through the ins and outs of electricity and electrical safety at Marion County Technical Center in West Virginia. Tim has been involved with SkillsUSA for a while and has had a student compete in the National competition held by this organization 13 times since he’s been involved with the program. This past year, one of Mr. Gump’s students placed 5th in the National at the Kansas City, MO, Skills National competition. Mr. Matthew Toothman achieved this in the industrial motor controls competition. Matt is now working for a company in Morgantown, WV, and has a great career ahead of him in this industry. Matt’s hard work earned him this achievement; a great foundation for one who just may be a future leader in our industry.

Mr. Lawrence Rossi of Fayette County Career and Technical Institute in Pennsylvania is yet another leader that has a great story to tell. Mr. Rossi has been teaching for 27 years and over the years that he has been involved with SkillsUSA, he has had four students compete at the National event and 11 students place at the state competition. Pennsylvania’s program is a little different from West Virginia’s. This past year, Mr. Patrick McDonough prevailed more than once before his trip to the National competition in Kansas City. Patrick competed with students from 10 other schools and took first place at regional competitions in Pennsylvania. After taking regionals, Patrick then competed with approximately 9 other students and took first place for the State competition. This earned him the opportunity to compete nationally where he placed 8th in the country for electrical construction, which used to be titled residential wiring. Patrick is currently on the job with an electrical contractor and has aspirations to achieve an IBEW Apprenticeship. Hopefully, 2014 will find him accepted into the NJATC program. Patrick is yet another future leader in our industry and his hard work has earned him a great start to his career.

It’s leaders like Jack Jamison, Tim Gump, and Lawrence Rossi and those around them that are planting the seeds that keep our industry alive. It’s hard workers and goal-oriented students like Mr. Matthew Toothman and Mr. Patrick McDonough that just may be future leaders of IAEI, IBEW, NECA ,or other organizations, working to guide and steer the future of our electrical industry.


Read more by Thomas A. Domitrovich

Tags:  Featured  January-February 2014 

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Vending Machines

Posted By Joseph Wages, Jr., Wednesday, January 22, 2014

Many people die each year from vending machines that accidentally fall over. This usually occurs when a product is not dispensed properly, and the machine is "shaken” to dislodge the product. You have a better chance of being electrocuted by a vending machine than winning the lottery. Your odds at winning the lottery vary but can be 1 in 175 million. The odds of being killed by a vending machine are 1 in 112 million.

Imagine, if you will, this scenario. It is late one night, and you decide to go fishing. Problem is the bait shop closed hours ago, but the moon is full, and the white bass is running. Fishing could be no better. What to do, what to do?

Or this scenario…. You are out of town and want to attend a sporting event. You want to fit in with the screaming fans. Problem is you left your tee shirt and hat at the house; you live over five hours away, and this is the only opportunity you have to attend a game. The stores are closed, and you’ve got to have it now! What to do, what to do?

Well, with everything in life comes opportunity. Some entrepreneur "feels your pain” and at the same time desires to make a quick buck. The products above are available to you 24 hours a day and 7 days a week. Enter the vending machine.

Most people are familiar with vending machines. Who hasn’t gotten the urge for a cold drink or a tasty bag of salty chips? Older, more seasoned citizens remember a time where you could get your favorite pack of cigarettes from one of these machines. What requirements did such a machine meet to achieve the status of "vending machine”?

Only the Code book knows!

The provisions for requiring ground-fault circuit-interrupter (GFCI) protection for vending machines were added to Article 422, Appliances, in the 2005 Code cycle. The U.S. Product Safety Commission had investigated four separate electrocutions that resulted in deaths since 1995 and three non-fatal shock hazards. These investigations spurred the new GFCI requirements. Like mostCode changes, a serious injury or death drove these requirements. Some of the unfortunate events happened around pools in hotel environments. Some occurred in other indoor and outdoor areas.

This author investigated one issue outside of a fire department several years ago. Late one evening, after a fire response, a firefighter wanted a soft drink. The barefoot firefighter received a tingle from the machine when he tried to place money into the machine. As the local electrical inspector, I was contacted the following morning. A tester was used, and it was determined that the metal casing of the machine had approximately 70 volts of circulating current on it. The machine was unplugged, and the vending machine provider called to remove the machine. Through sheer chance, a fatal electrocution was adverted in this situation. Had this vending machine been GFCI-protected, the faulty condition would have been discovered much earlier, and the potential danger avoided all together.

With vending machines come GFCI protection

Vending machines require GFCI protection. But what is a GFCI? Again, let’s visit the definitions to see if we can find an answer. This time, we find our help located in Article 100. Let’s see what it says:

Ground-Fault Circuit Interrupter (GFCI). A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof within an established period of time when a current to ground exceeds the values established for a Class A device.
Informational Note: Class A ground-fault circuit interrupters trip when the current to ground is 6 mA or higher and do not trip when the current to ground is less than 4 mA. For further information, see UL 943, Standard for Ground- Fault Circuit Interrupters.

(2011 NEC)

Now that we are straight what a GFCI is let’s see where we are required to provide this protection to vending machines. This requirement is found in section 422.51.

422.51 Cord- and Plug-Connected Vending Machines.

Cord- and plug-connected vending machines manufactured or remanufactured on or after January 1, 2005, shall include a ground-fault circuit interrupter as an integral part of the attachment plug or be located within 300 mm (12 in.) of the attachment plug. Older vending machines manufactured or remanufactured prior to January 1, 2005, shall be connected to a GFCI-protected outlet.

Informational Note: For further information, see ANSI/UL 541-2005, Standard for Refrigerated Vending Machines, or ANSI/UL 751-2005, Standard for Vending Machines. (2011 NEC)

I would be remiss not to mention a new requirement for the 2014 NEC that deals with GFCI requirements being extended to vending machines that are "other than” cord- and plug-connected.

422.51 Vending Machines.

(B) Other Than Cord- and Plug-Connected. Vending machines not utilizing a cord and plug connection shall be connected to a ground-fault circuit-interrupter protected circuit.(2014 NEC)

This is important because some of the vending machines you will encounter will not be connected by a cord- and plug-connection. It is essential to know which edition of the Code is being enforced in the jurisdiction in which you are working. Consulting with the local authority having jurisdiction (AHJ) is always a good move on your part. But what if I am the local AHJ? What then? Help is available with interpretations from the NFPA and from other code experts within the electrical industry.

Where can the GFCI device be installed?

A new requirement was placed at 422.5 for the 2014 NEC Code cycle. It reads as follows:

422.5 Ground-Fault Circuit-Interrupter (GFCI) Protection. The device providing GFCI protection required in this article shall be readily accessible. (2014 NEC)

This was an important addition to the Code. A proposal was submitted to Code-making Panel 17 that included substantiation stating that, in many cases, the manufacturers of GFCI devices require routine testing of these devices, usually on a monthly basis. This requirement helps to ensure that the device is providing the protection it was intended to provide. The panel was in agreement and placed this new requirement in the 2014 NEC.

GFCI protection can be supplied by items other than a receptacle. Many are familiar with a circuit breaker being used for this function. Other devices can be located in the attachment cord of the appliance and still need to be readily accessible for observation and testing.

If we look at the definitions, we find one for readily accessible located in Article 100. Let’s look at the definition:

Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, and so forth. (2011 NEC)

A fully loaded vending machine can be very heavy. Moving it to reset or test the GFCI could be extremely difficult. With the new requirements that were added at 422.5 for the 2014 Code cycle, it has been made clear that GFCI devices are required to be accessible for these appliances.

What is a vending machine?

To begin our search of understanding we need to know what constitutes a vending machine. In order to do that, we need to locate a definition. The makers of the Code have helped us out by including such a definition within the National Electric Code. This definition is located in 422.2 of the 2011 NEC. Let’s review:

Vending Machine. Any self-service device that dispenses products or merchandise without the necessity of replenishing the device between each vending operation and is designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means. (2011NEC)

Now look closely at which requirements must be met to achieve the status as vending machine. The definition can be broken into three requirements; all of which must be met. Let’s break it down from the definition:

1. It must be a self-service device.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

Now that we have the requirements broken out, I can see several everyday pieces of equipment that meet these requirements. These pieces of equipment dispense many items other than cold drinks and candy bars. A few examples would be hot coffee, sandwiches, and photo products.

Applying the Requirements

Now we can apply these requirements to items that we might consider a vending machine [see definition of vending machineabove]. I have included a few for your consideration and amusement:

 

Photo 1.  Self Service Drink Cabinet

1. It must be a self-service device.

Okay we are required to get our own drink from the machine. Meets Item #1.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

By the looks of it, this machine meets the requirement of Item #2.

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

This machine is not designed to accept money or any of the other forms of payment found in Item #3. Therefore, this cannot be considered a vending machine.

 

 

Photo 2.  Red Box Video Machine 

1. It must be a self-service device.

Okay we can select our movie of choice and is self-service. Meets Item #1.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

This machine dispenses an item until it runs out of the item (similar to a drink machine). Meets Item #2.

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

This item is designed to accept a payment for dispensing the desired product. Therefore, it can be considered a vending machine. Remember 422.51(B) for other than cord- and plug-connected vending machines.

 

 

Photo 3.  Fountain Drink Dispenser

1. It must be a self-service device.

Okay we can select our drink of choice, and it is self-service. Meets Item #1.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

This machine dispenses an item until it runs out of the item. Meets Item #2.

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

This machine is not designed to accept money or any of the other forms of payment found in Item #3. Typically, the drink is paid for at a counter in the store; therefore, this cannot be considered a vending machine.

 

 

Photo 4.  ATM Machine

 

1. It must be a self-service device.

Okay we can select the amount of currency to withdraw, and it is self-service. Meets Item #1.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

This machine dispenses currency until it runs out. Meets Item #2

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

To use this item, one must have a bank ATM Card which is inserted to begin the process of receiving a product. This item is designed to accept a payment for dispensing the desired product. Typically, you are charged a fee for the financial transaction. Therefore , it can be considered a vending machine. Or can it? What other factors do we need to consider before making this determination?

 

 

 Photo 5.  

1. It must be a self-service device.

Okay we can select our bait of choice and it is self-service. Meets Item #1.

2. It must dispense a product or merchandise without the necessity of replenishing the device between each vending operation.

This machine dispenses an item until it runs out of the item. Meets Item #2.

3. It must be designed to require insertion of coin, paper currency, token, card, key, or receipt of payment by other means.

This item is designed to accept a payment for dispensing the desired product; therefore, this can be considered a vending machine.


But what about UL and other NRTL Listings?

We have seen some examples of applying the vending machine definition from the NEC to items that inspectors are being asked to inspect on a daily basis. The definition of vending machine states that it must dispense a product or merchandise and require a payment means. I overheard a group of inspectors feverously discussing this topic. Remarks were made that the ATM dispensed a product (money and a receipt), and it also required payment (as in a banking fee that is associated with each transaction). Obviously, there are AHJs encountering items such as these and having to make a determination. Some are coming down on the side of safety and requiring these to have GFCI-protection, using the requirement found for vending machines in Article 422.

 

Photo 6.  Large ice machine 

Let’s see if the Underwriters Laboratory standards or other NRTL (National Recognized Testing Laboratories) have something to say.

ATMs (automatic teller machines) are listed under Banking Equipment (BALT) and evaluated to UL 60950. In reviewing product category (BALT), it does not offer any information towards a requirement for GFCI protection of this equipment. The information here points us towards additional information in category Electrical Equipment for Use in Ordinary Locations (AALZ). The informational notes following the requirements at 422.51 tell us that vending machines are listed to UL 541 or UL 751. This may be an area the installer and the AHJ discuss prior to beginning the project.

As the AHJ, an important document to have and to be familiar with is the most current UL Guide Information for Electrical Equipment (White Book). This document is extremely helpful to the inspector and the installer as to "filling in the blanks” of what is not in the NEC. Find the listing mark on the piece of equipment you are inspection or installing. This will give you information towards finding pertinent information from the standards about this equipment. Use the information on the UL Label and reference the "Index of Product Categories and Industry Terms” in Appendix C of the UL White Book. This will guide you towards the Guide Information for the category. The Guide Information will tell you which standard was used for the listing.

Here are a few of the items that UL 751 includes as types of vending machines:

  • Balloon Vending Machines
  • Bowl Dispenser Kits
  • Candy Vending Machines
  • Coffee and Chocolate Vending Machines
  • Coffee Vending Machines
  • Cup Vending Machines
  • Hot Canned-food Vending Machines
  • Hot Drink Vending Machines
  • Hot Food Vending Machines
  • Ice-dispensing Vending Machines
  • Oil Can Vending Machines
  • Pastry Vending Machines
  • Photo Vending Machines
  • Water Vending Machines

The standards may or may not provide the necessary information for the AHJ or the installer to make a determination about all equipment that is encountered. Remember to consult the manufacturer’s installation instructions that accompany this equipment. The safety of the end user should be the ultimate concern. Working together, the AHJ and the installer can provide an electrically safe environment for the general public.

Conclusion

Hopefully, we’ve learned something more about vending machines. Today’s society is not your mom and pop society anymore. Society is on the move, and it seems like it never stops. Can you remember going on a peaceful trip to the mountains, or to the beach, and truly saying you had escaped. Nowadays, we take along the cellphone, the laptop, a digital camera, and get there with the help of a GPS device. Our cell phones are always available and keep us from getting lost while traveling to and from our favorite restaurant. During this journey, there are vending machines. From these machines, you can pay for and receive charging services for your cell phone or other electronic devices.

Along the way, there are vending machines that allow us to purchase movies and video games to play in the vehicle to keep the kids quiet and the parents sane on those long trips. Some vending machines even allow us to purchase ice in bulk to ice down the beverages, or maybe, if you’re lucky, that opening day deer carcass for the trip back home.

Vending machines have evolved too. We can get practically anything from these machines. Now that I think of it, there are vending machines that do not require electricity. I wonder if a receptacle is required because they meet the definition of a vending machine, even though they do not require electricity. I’ll leave a little exploring and legwork up to you!

References

Tom Lichtenstein from Underwriters Laboratories for assistance with the UL Standards

NFPA, National Electrical Code, 2011 and 2014 editions

UL Guide Information for Electrical Equipment (White Book), 2013


Read more by Joseph Wages, Jr.

Tags:  Featured  January-February 2014 

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Vertical MC Cable Support in the 2014 NEC

Posted By Phil Simmons, Wednesday, January 22, 2014

The 2014 NEC has added language that affects only metal-clad (MC) cables with phase conductors 250 kcmil or larger. You may think of MC cable as primarily a branch circuit wiring method, but larger size MC cables are often used for feeder circuits in high-rise buildings or other large installations. Many of the support and securement requirements are the same regardless of the size of the cable; however, there are different securing requirements for MC cable with very small or very large conductors.


A proposal and comment submitted during the 2014 NEC revision cycle, along with testing performed at UL, resulted in a change to the securing requirements in 330.30(B). For vertical installations, any listed MC cable is allowed to be secured at 10 foot intervals (rather than the 6 foot interval required in the 2011 NEC) as long as the cable contains ungrounded conductors 250 kcmil or larger.

Note that the language says that the MC cable must be listed, not "listed for the purpose.” UL 1569 is the product standard used to list MC cable, and there is no special test in the standard for MC cable used in a vertical installation. Additionally, there are no requirements in the NEC for supporting the conductors inside the cable, unlike the requirements for conductors in raceway.

Any of the commercially available MC cables listed to UL 1569 having ungrounded conductors 250 kcmil or larger can be used with this new less stringent securing requirement. This change will allow for fewer clamps in vertical installations, while still providing a safe and secure installation.


Phil Simmons is technical director for the National Armored Cable Manufacturers Association. He formerly served as chief electrical inspector for the state of Washington, for IAEI as executive director and is a member of NEC CMP-5.

Tags:  Featured  January-February 2014 

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"The Look of IAEI"

Posted By Mark Hilbert, Wednesday, January 22, 2014

I am truly honored to be representing our Association for the next year as the international president. I can only hope that I can do as much for our Association during my term as those who have come before me. However, the year ahead of us is not about an international president alone; it is about us as an association and what can we do for IAEI. This will be a challenging year as we are entering, I believe, into an era of significant realignment and restructuring which will stretch well beyond my time as president.

During the next few years, we are going to have to work together as a team to bring this great association into the future, while preserving its integrity and mission of promoting electrical safety throughout the industry through education, certification of inspectors, advocacy, partnerships, and expert leadership in electrical codes and standards development. We are going to have to answer many questions related to "What do we want IAEI to look like going forward?”

It is clear the association has become fragmented in many ways, so there are many faces or "looks” to us. This was the message in the "Branding” presentation by CEO, Executive Director David Clements at this year’s section meetings. Our logo is just one of the "looks of IAEI.” Because our sections, chapters, and divisions act independently of the International Office in many ways, we all have our own "look.” We need to bring some commonality to our logos, so we look like one association.

Our founding fathers gave us "a look” back in 1928 with the keystone logo. I thought this was going to be an easy decision for me; hands down, it is the keystone logo. I am pleased it is on my president’s ring, but I have to wonder if it is the right one for the association going forward. It very well may be. We also have to consider the "lightning bolt” logo of the IAEI News. We have used that logo on shirts, hats, vests, etc. I have to admit that I have already had members tell me they like it better than the keystone logo. We have work to do!

Our standing committees will still be looking at long range items along with membership and education as they have been, but we will need to focus on the "looks of IAEI.” This goes beyond the logo issue to items like the board’s structure, the relationships between the International Office and the sections, chapters and divisions, codes and standards work and how we approve technical committee members. Again, what do we want IAEI to look like? Right now it takes 12 years on the International Board of Directors to become president. I ask you: "How many jurisdictions do you think would be willing to support an individual for 12 years these days?” The reality of it is, there are not many. I was very fortunate and grateful to have the support of the State of New Hampshire Electricians Licensing Board and the Department of Safety for most of those years. Another question to ponder is: "How many of the younger folks coming into the association will be able to dedicate that much time?”

Our association’s operating rules, bylaws, and overall structure date back to 1928 when the association was truly a volunteer driven association. They have been modified over the years, but they were never actually restructured to fit the way business is, or should be, done these days. Another "look of IAEI” we have to consider.

I am merely the coach of the team for one year, but I cannot tell you how excited I am to be working with the other members of the Board of Directors, as well as with sections, chapters and divisions. It is going to be a tremendously busy year for all of us and this will be especially true for the International Board of Directors. Our working groups will be focused on the specific "looks of IAEI.” I was pleased to note the dedication, open-mindedness and the excitement amongst the International Board of Directors and the International staff at the November 2013 meetings. I cannot say enough about our CEO and the International staff. I can truly tell you our Association has benefited significantly from their leadership, dedication, and commitment. As I said, it is an honor to represent this team.

Reaching the presidency in our Association would not have been possible without my wife Wanda’s love, support and encouragement. I also wish to thank the Granite State Chapter and Eastern Section for the support and encouragement along the way. I am proud to be a member of both. There are far too many folks for me to start thanking everyone who has helped me reach this level. You know whom you are and how much I appreciate all you have done. However, we all have a few "significant moments” that stand out in our IAEI journeys.

The first significant moment for me was the day Joe Bourque, state electrical inspector from New Hampshire, encouraged me to submit an application for a vacated state electrical inspector’s position. At the same time, he gave me an IAEI membership application, saying, "Here, these go together!” He was not kidding. I remember the night Jeff Sargent, founding member of the Granite State Chapter, and I were attending a chapter meeting and he said to me, "Wouldn’t it be nice if the Granite State Chapter had a section president?” I remember riding up in the elevator at Kutcher’s in NY State some years later (I did not say all the memories were good) with Bob Venuti, Leo Martin, Jack Mangan and Tony Montuori. Bob Venuti was Eastern Section president at the time and introduced me to Tony, telling him that he thought I would be a good section president. Tony asked me how old I was and when I replied, he said, "You’re young enough to be an international president.” I will never forget these moments and just want to say, thanks for planting those seeds! It has been a fantastic experience.

 

About the President

Mark began his career as a construction electrician following his graduation from the Greater Lawrence Regional Vocational Technical High School located in Andover, Massachusetts, in 1973, and currently holds a master electrician’s license in two states.

Mark joined the State of New Hampshire Electricians’ Licensing Board in 1993 as a field inspector. He was promoted to the position of chief electrical inspector in July 2001. Prior to joining the State of New Hampshire, Mark was a self-employed electrical contractor located in Southern NH for over twelve years, and worked as a maintenance electrician in general industry for over seven years prior to starting his own business.

Mark is a past president of the Granite State Chapter of IAEI, which he joined in 1993. He is an inspector member of the Board of Directors, has been the Chapter’s Education chairperson for over fifteen years, and is the Granite State Chapter delegate to the Eastern Section. He is a certified electrical inspector, holding certificates from IAEI in One- and Two-Family Dwellings, Electrical General, and Electrical Plan Review. He has represented IAEI as an alternate member on NEC Code-making Panel 4 and is currently a principle member and chair of Code-making Panel 2. Mark is also principle member and chair of the Technical Committee on Electrical Equipment of Industrial Machinery, NFPA 79.

He was a National Electrical Code instructor for the Laconia, NH, Adult Education Electrical Apprentice Program for five years until he joined the National Fire Protection Association in April of 2000 as a consultant, providing advisory service for the Electrical Engineering Department, and as a National Electrical Code seminar instructor. In his capacity as a seminar instructor, he has been involved in technical program development and has taught the National Electrical Code, and has brought the message of electrical safety through NFPA 70E domestically and internationally. Mark is also an instructor for IAEI.

Mark and his wife Wanda reside in the small Town of Wolfeboro, NH, which is located in Central New Hampshire’s scenic Lakes Region. Mark and Wanda enjoy traveling around the United States seeing the sights and history. In their spare time, they enjoy riding their Harley Davison motorcycle, attending NASCAR races, and spending time with their four boys: Scott, Eric, Sean and Jason and their five grandchildren Bryton, Addison, Nathan, Azaya and Alaina.

Most of all, Mark is proud to be an electrician, an electrical inspector and part of a profession where knowledge is so willingly shared. Ultimately, his goal is to give something back the industry that has given so much to him.


Read more by Mark Hilbert

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Financial Resolutions for the New Year

Posted By Jesse Abercrombie, Wednesday, January 22, 2014
About 45% of Americans usually make New Year’s resolutions, according to a survey from the University of Scranton; but the same survey shows that only 8% of us actually keep our resolutions. Perhaps this low success rate is not such a tragedy when our resolutions involve things like losing a little weight or learning a foreign language. But when we make financial resolutions — resolutions that, if achieved, could significantly help us in our pursuit of our important long-term goals — it’s clearly worthwhile to make every effort to follow through.

So, what sorts of financial resolutions might you consider? Here are a few possibilities:

Boost your contributions to your retirement plans:Each year, try to put in a little more to your IRA and your 401(k) or other employer-sponsored retirement plans. These tax-advantaged accounts are good options for your retirement savings strategy.

Reduce your debts:It’s not always easy to reduce your debts, but make it a goal to finish 2014 with a smaller debt load than you had going into the new year. The lower your monthly debt payments, the more money you’ll have to invest for retirement, college for your children (or grandchildren), and other important objectives.

Build your emergency fund: Work on building an "emergency fund” containing six to twelve months’ worth of living expenses, with the money held in a liquid account that offers a high degree of preservation of principal. Without such a fund, you might be forced to dip into your long-term investments to pay for emergencies, such as a new furnace, a major car repair, and so on. You might not be able to finish creating your emergency fund in one year, but contribute as much as you can afford.

Plan for your protection needs: If you don’t already have the proper amounts of life and disability insurance in place, put it on your "To Do” list for 2014. Also, if you haven’t taken steps to protect yourself from the considerable costs of long-term care, such as an extended nursing home stay, consult with your financial professional, who can suggest the appropriate protection or investment vehicles. You may never need such care, but that’s a chance you may not want to take — and the longer you wait, the more expensive your protection options may become.

Don’t overreact to market volatility: Too many people head to the investment "sidelines” during market downturns. But if you’re not invested, then you miss any potential market gains — and the biggest gains are often realized at the early stages of the rally.

Focus on the long term: You can probably check your investment balance online, which means you can do it every day, or even several times a day — but should you? If you’re following a strategy that’s appropriate for your needs, goals, risk tolerance and time horizon, you’re already doing what you should be doing in the long run. So there’s no need to stress yourself over the short-term movements that show up in your investment statements.

Do whatever you can to turn these New Year’s resolutions into realities. Your efforts could pay off well beyond 2014.


Read more by Jesse Abercrombie

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Now that industrial GFCIs are here, inspectors have a proactive option for shock protection

Posted By Nehad El-Sherif, P. Eng., Wednesday, January 22, 2014

UL Class A ground-fault circuit interrupters (GFCI) began to be required in kitchens, bathrooms and outdoor outlets in the early ’70s, and have saved many lives over the years: According to the Consumer Product Safety Commission, household electrocutions decreased from 270 in 1990 to 180 in 2001. But what about in the workplace? Class A GFCIs cannot be used where the electrical equipment runs on 480 or 600 V. Yet the danger of electrocution is real. From 2003 to 2009 there were 801 fatal workplace accidents caused by worker contact with electrical current (not including the construction industry).

 

Photo 1. Industrial Shock Block GFCI for circuits 208 V to 600 V (208, 240, 480, and 600 V.) 

Traditionally, measures to prevent shock have included insulated tools, insulated gloves, lockout tagout, etc., but all of these options are reactive, and none proactively eliminates the hazard. There are ground fault relays (GFRs), but those react too slowly to provide people protection, and Class A GFCIs are not practical for industrial settings.

The situation is finally changing, based on the recently introduced special purpose GFCIs in UL 943C, where new classes are added for 480 and 600 V applications. Although the new classes of devices trip at higher current levels (20 mA instead of 6 mA), UL calls these devices GFCIs, which UL defines as "a device intended for the protection of personnel.”

The increase in personnel protection trip level of the new GFCI classes is allowed by UL assuming the availability of a reliable ground in parallel with the body. During a fault, the grounding conductor will shunt the fault current around the body and cause the device to trip. This provides the let-go protection, while the 20 mA threshold provides protection against fibrillation. (If there is no grounding conductor, such as in two-wire household products, then the GFCI must provide both let-go and fibrillation protection, and a Class A device is required.)

Impedance of the human body decreases rapidly above 150 volts to ground, and GFCI protection would require impossibly fast trip times. That’s why UL 943C defines different classes of GFCI based on the type of grounding (figure 1). If reliable grounding is provided in a circuit of less than 150 volts to ground, then the touch voltage will be less than 150 volts to ground and a Class C GFCI may be used.

 

Figure 1.  How to determine the class of device for a particular application. This figure appears in UL 943C as Figure 1.1 and is used with permission. Copyright © Underwriters Laboratories Inc. UL 943C, Edition 2, 2012.

If the circuit voltage is between 150 and 300 volts to ground, then the solid reliable grounding conductor must be the same size as the hot (ungrounded) conductor. This forms a voltage divider with two equal impedances and acts to reduce the touch voltage to half (150 volts or less). Then a Class C GFCI may be used.

When the voltage to ground exceeds 300 volts, UL provides two options. For Class D GFCI protection the circuit requires a low impedance ground that reduces touch voltage to 150 V or less during a fault.Class E GFCI protection uses a standard size grounding conductor but requires a high-speed trip time to limit the body’s exposure and resulting injury.

Class E GFCIs have the same time vs. current characteristics of Classes A, C, and D up to a fault current of 300 mA (150 V to ground touch voltage with a 500-ohm body resistance). When the fault current exceeds 300 mA, the trip time formula changes to a high speed trip requirement.

For the purposes of this article, it will be convenient to refer to Class A GFCIs as residential GFCIs and refer to the other classes (Class C, Class D and Class E) as "industrial GFCIs,” although UL makes no such distinction.

These other classes of UL-listed GFCIs have recently become available, and they can make worker shock protection proactive, significantly reducing the risk of injury and death due to shock in the workplace. Some industry players believe that, as awareness of UL 943C increases, technology adoption will also increase and, perhaps, the electrical codes will be updated to require GFCIs in more industrial applications. And while the NEC® and CEC® do not yet require broad use of industrial GFCIs, some sections recommend their use for specific applications.

Electrical inspectors and installers may not know that these devices exist, as until now there was no UL-listed device that could protect industrial workers from electrocutions. Electrical inspectors will want to become familiar with the relevant standards and installers will want to understand how to apply them. What’s more, as industrial GFCIs are gradually adopted into use, inspectors will start to encounter them; inspectors should understand how they operate and how they are properly installed.

A little history

In 2000 UL addressed the need for GFCIs designed for higher power with a draft Outline of Investigation called 943C, and revised it in 2009, but it was not until 2012 that commercial products became available. Many users are still unaware that such solutions are available and not very many workplaces have installed them, still exposing workers to risk of electrocution.

Where industrial GFCIs are used

Any place where water, people, and significant voltage equipment meet presents the potential for a shock hazard. Industrial GFCIs are being installed on equipment subject to washdown, such as food and beverage facilities; in processing plants handling wet materials using large pumps or mixers; and in water and wastewater facilities, municipal fountains and even amusement parks.

Industrial GFCIs are also used for outdoor applications like welding, mining, or anywhere workers use portable equipment or equipment with long power cords or cables. It is expected that portable applications will be one of the first places for adoption of industrial GFCIs.

Classes of industrial GFCIs

GFCIs for residential use are listed under UL 943 as Class A, but they are not suitable for industrial use for two reasons: they are rated only for 120 and 240 V installations, and their 6 mA trip level is typically too low for industrial applications. Many industrial electrical systems have normal leakage current greater than 6 mA, in which case a residential GFCI would never leave trip mode and the circuit would never power up.

UL 943C has three classes for industrial GFCIs: Class C, for use in circuits with maximum line-to-ground voltage of 300 V where reliable equipment grounding or double insulation is provided; Class D, for use in circuits with line-to-ground voltage higher than 300 volts with oversized grounding to prevent the voltage across the body during a fault from exceeding 150 volts; and Class E, which covers systems similar to Class D, but with high-speed tripping required, therefore the oversized ground of Class D is not required. Figure 1 shows how the class of device for a particular application is determined.

There was also a Class B, which applied only to swimming pool underwater lighting fixtures that were installed prior to local adoption of the 1965 edition of the NEC. These are considered obsolete and have been removed from UL 943, the UL Standard for Ground-Fault Circuit-Interrupters. They will seldom be encountered in practice and will not be further discussed here.

Industrial GFCIs differ from Class A units in another important way: UL requires that they monitor the equipment ground wire, to detect whether the monitored equipment is properly grounded, and to cause a trip if the grounding connection is lost.

Inverse-time curve

According to UL, Class C, Class D, and Class E GFCIs follow the same inverse-time protection curve as Class A GFCIs, which is defined by this equation.


This curve is shown in figure 2, where the current (I) is in mA and the time (T) is in seconds. The unit should trip in about 1 s at a current of 20 mA (quickly enough to prevent injury at that current level), and within 20 ms at currents of 300 mA or higher. The higher the current, the faster the GFCI must trip. The advantage of the inverse trip curve is that it minimizes nuisance tripping for transient low-current faults while providing full people protection from ground-fault current.

 

Figure 2.  UL 943C requires industrial GFCIs to follow this trip curve.

In practice, a Class C, Class D and Class E GFCI will trip at current between 15 and 20 mA (in order to allow for a range of operating conditions). UL 943C Figure 1.1 states that Class C GFCIs must "provide protection against ventricular fibrillation (let-go protection optional).” Clause 15.2 of UL 943C allows the lower limit of the trip threshold of a Class C device to be reduced to any value between 6 and 15 mA to provide some limited let-go protection as an option.

UL 943 says that Class A GFCIs should have the inverse-time trip curve shown in figure 2 over a leakage current range of 6 to 264 mA, but some manufacturers of lower-priced Class A devices do not implement the curve because it makes the design more complicated, and instead use an instantaneous response that is lower than the quickest response required by the code just to pass testing. The UL curve is the absolute highest time response accepted but it is not restrictive. A device will fail UL testing if it responds to a fault slower than the curve suggests but will pass as long as the response time is less than the curve time. Too-quick response to transient ground-fault currents of low magnitudes will cause nuisance tripping; this is the main reason for not using residential type Class A GFCIs in industrial applications even where the line-to-line voltage is 240 V or lower and the system leakage is less than 6 mA.

How to install industrial GFCIs

An industrial GFCI can be built into a panel or a cabinet, as shown in figure 3; there are units with their own NEMA 4X enclosures that can be added to existing equipment. A separate load ground monitoring wire must be connected to the chassis of the equipment to be protected through a termination device, as shown in figure 4.

 

 Figure 3.  An industrial GFCI can be built into a panel or a cabinet, as shown, or added to existing equipment (using units with their own enclosures). 

 

Figure 4.   Circuit diagram of an industrial ground-fault circuit interrupter

As shown in figure 4, some GFCIs have internal fuses to increase their interrupting capacity, protect the internal contactor and in some cases eliminate the need for an upstream current-limiting device. In addition, some models can detect undervoltage, brownout, and contactor chatter.

EGFPDs and how they differ from GFCIs

Under certain circumstances the 20 mA trip level of an industrial GFCI can make its use impractical. In those cases, an equipment ground-fault protection device (EGFPD) can be used. EGFPDs offer protection similar to GFCIs but are allowed by UL to have an adjustable trip level (GFCIs have a fixed trip level) and monitoring the equipment ground wire is not required (a mandate for industrial GFCIs). EGFPDs can be adjusted to trip in the range of 6 to 50 mA. EGFPDs are rated by UL for equipment protection only.

Don’t confuse a GFCI or EGFPD with a ground fault relay (GFR). Unlike a GFCI or EGFPD, both of which contain their own circuit interrupters, a GFR works by detecting a ground fault and sending a signal to the trip input of an upstream circuit breaker or contactor. Because GFRs have adjustable trip times, and power breakers often take up to 50 ms to trip, they do not protect people against cardiac arrest.

Summary

Industrial GFCIs provide workers with vital protection against shock injury and electrocution at a cost that is trivial compared to the multiple costs involved with a serious injury or a fatality. Inspectors can play a critical role in informing users of this technology to help them increase safety.


Nehad El-Sherif, P.Eng. is the technical product specialist for the protective relay products line for Littelfuse. He received his B.Sc. and M.Sc. in Electrical Engineering from Ain-Shams University, Cairo, Egypt, in 2001 and 2005. He serves on several professional societies, committees and working groups including UL STP 943, CSA C22.2 No.144 standard committee, IEEE IAS and the IEEE Working Group on Industrial and Commercial Power Systems Communication Based Protection and SCADA. He is a registered professional engineer in Saskatchewan and has a patent pending. He is also an IAEI associate member, Canadian Section. Nehad can be reached by email at nel-sherif@littelfuse.com.

Tags:  Featured  January-February 2014 

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Articles 312 and 314

Posted By Randy Hunter, Wednesday, January 15, 2014

Our focus for this article will be 2011 NEC Articles 312 and 314. These two articles deal with similar subjects, so they have some conceptual overlaps. Article 312 deals with Cabinets, Cutout Boxes and Meter Socket Enclosures. Article 314 deals with Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings; and Handhole Enclosures.

We will not spend a great deal of time on Article 312 since this article is typically applied to current transformer (CT) cabinets, utility cutout boxes and meter bases. For the jobs inspected by combination inspectors, most of these items will be regulated by the serving utility and are, therefore, out of the inspector’s jurisdiction. If you have a question on an installation dealing with one of these items, contact your local utility and ask for their regulations or approved design documents to see what they require. A few times, I have seen out of area contractors come into town and complete installations which are the way they have done them in other locations, only to be surprised during inspection to find out they needed to change out equipment to meet local utility requirements.

 

Photo 1. This is a good example of the wire bending space requirements found in Article 312.  The conductors that enter from the top and terminate in the highest lugs would be considered as entering the opposite wall as in 312.6(B)(2); all the others would have to meet the requirements of 312.6(B)(1). 


Article 312 begins with installation requirements for damp and wet locations. Some basic items here are related to prevention of moisture accumulation within the enclosures and the need for a ¼″ airspace between the enclosure and the mounting surface. Positioning within walls is covered next, and you are allowed a  ¼″ setback if in concrete, tile or other non-combustible materials. If you have a combustible finish wall, you must have cabinets flush or projecting past the surface. These are some of the most basic items to look for, but please review your codebook to fill in the other items I have skipped.

One of the most important items (in my opinion) is the Deflection of Conductors requirement in 312.6. This is the portion of the code that gives us the required bending space for conductors, which depends on both the size of the conductor and where it enters the enclosure in relation to the termination position. Naturally, bending the conductor allows us to have a slight reduction in the required space, and it is easier to make a 90 degree bend into a terminal point. Please keep in mind that these are based on the minimum bending radius of conductors, and we should not make sharp right-angled bends.

 

Photo 2. This is a steel box with a trade size of 4 x 2 1/8, so in Table 314.16(A) we find a volume of 30.3 cubic inches. However, the plaster ring has a volume of 4.5 cubic inches (as seen in the photo) for a total of 34.8 cubic inches. 

When the conductors enter the wall of the enclosure opposite the termination, then we have to make two offset bends (unless you have the rare occasion where the conductor enters directly across from the termination), thus the need for additional space with these connections. Read the language carefully in order to understand when to apply each table, and familiarize yourself with both Tables 312.6(A) and (B). Table 312.6(A) deals with conductors not entering or leaving the opposite wall, so if we are using a typical wall mount panel and we have the conductors entering the top of the enclosure and the terminations of the branch circuit breakers are horizontal (meaning they are facing 3 oclock and 9 oclock), then this table gives us the required bending space. If we use the same example and the conductors enter in the right side of the enclosure they would be opposite the termination, and Table 312.6(B) would be used.

Often we have parallel runs for the same circuit that have to be terminated into the same device. This is where we apply the extra columns of these tables under the headings of "wires per terminal.” This concludes our brief review of some of the requirements in Article 312. In my experience, these are the things that combination inspectors encounter most often.

 

Photo 3. Plastic box volume cannot be found in Table 314.16(A).  Therefore, each box is required to be marked with the volume.  Also, note that in the lower right corner of the inset photo, the manufacturer helps you by giving the maximum number of conductors allowed if using all the same size.  The middle line indicates that fourteen 12 AWG conductors are permissible.  Also, note that these cable clamps are considered internal.

Installations that must comply with Article 314 are found more often in the combination world, and yet these rules are frequently misunderstood or not enforced. Please review the beginning of this article on your own, and we will start our coverage with 314.16.

In 314.16, we find the allowable number of conductors in outlet, device and junction boxes, and conduit bodies. First, let’s get conduit bodies out of our way in 314.16(C). First, I have to explain that we have two types of conduit bodies: standard conduit bodies and short-radius conduit bodies, which in the field are commonly referred to as SLBs (see 314.16(C)(3) for details).

Conduit bodies are made with an interior volume that is generally twice the volume of the largest possible conduit entrance. So if the conduit fill requirements are followed, we typically never have a problem with conduit body fill issues. The field issues we usually see with conduit bodies come from splices, taps or devices. In 314.16(C)(2) we find that only where we have volume measurements clearly marked by the manufacturer are we allowed to have splices or taps. If you see splices or taps in a conduit body, please refer to Table 314.16(B) for a volume calculation factor to be used based on the number of conductors. You have to check and see if they have exceeded the volume of the conduit body as labeled.

Enough said on conduit bodies, now let’s get to boxes. Overfilled boxes lead to all kinds of issues. We need enough room within each box for any devices to be used, as well as sufficient space for heat to dissipate without causing damage to the conductors or the devices. Devices today seem to be getting larger and larger. USB outlet combination devices are the latest devices Ive seen which are larger than the normal receptacle; and, of course, we have dimmers or occupancy sensors which are larger than normal switches.

 

Photo 4. This photo illustrates both internal cable clamps (top and bottom) and an external clamp located on the right side.

With this in mind, we have limits on how many conductors we allow. I have seen electricians who have used the end of hammer handles to force conductors back into a box to create enough room for the devices to be installed; not a good practice, obviously! At times, this type of abuse can lead to damaged insulation of conductors, loosening of terminations within wire nuts, and other dangerous conditions.

If we are dealing with industry standard metal boxes, we should refer to Table 314.16(A) which gives us the standard dimensions and volumes of these boxes. I start here because these boxes are not marked with a volume number. The metal boxes usually also accept what is known as a plaster ring, or at times extension rings. In these cases, as long as the plaster trim ring or extension box has a volume measurement on it, then you would add this to the box volume for the total volume of the assembly.

When we deal with plastic boxes, which are not just simple cubes in their design, the manufacturers are required to mark the volume measurement on the box. These are usually embossed on the plastic box. So how do these volumes relate to conductors and devices? We need to use Table 314.16(B), which gives us a volumetric requirement for conductors size 18 AWG through 6 AWG. Most commonly, we use 14, 12 and 10 AWG, so I would encourage you to memorize those numbers: 14 AWG has a value of 2 cubic inches; 12 AWG jumps to 2.25 cubic inches; and 10 AWG is 2.5 cubic inches. We often have boxes that do not have all the same size conductors, as it is common to have 12 AWG for receptacles and 14 AWG for lighting. So, if you have a switched outlet, there will be both 14 AWG and 12 AWG in the same multi-gang switch box. If the box contains only one size conductor, then it is quite simple to follow the numbers in Table 314.16(A) or the numbers given by the plastic box manufacturer, embossed into the box.

Now that we have some of the basics covered, let’s go back and review 314.16(B), which is broken down into five sections. First, we are told that each conductor that originates outside the box and terminates within the box will get one volume count according to the size of conductor. If you have pass-through conductors that do not terminate to anything within the box, we have to count each of these as one volume count. If you have conductors that pass through the box but also have a large loop of excess wire (double the minimum required for free conductors), then we count those conductors as a double volume count. If you have a pigtail for makeup that does not leave the box, it doesn’t have to be counted.

Now we have to consider the cable clamps. If the box has any cable clamps within the interior of the box, we have to count them as a single volume count of the largest conductor within the box. So if we use one clamp or four clamps, it is still just a single volume count. If we have any lighting support devices, also called studs or hickeys, then again we have to add one volume count based on the largest conductor.

That brings us to devices, receptacles and switches. Each strap or yoke that holds a receptacle or switch, or multiple receptacle or switches, has to have a double volume count based on whatever size conductors are connected to that device. If you are using a larger device (for example a 50-amp receptacle) that is wider than a single (2 inch) device box, then you have to count a double volume allowance for each gang required for mounting such a device.

 

Photo 5. This is an example of a power distribution block.  In 314.28(E)(4), the code requires the live parts to be covered.  This photo shows a totally insulated unit which is considered finger safe.

The last item to cover in box fill calculations is the room needed for the equipment grounding conductors. The basic rule is that we must take a single volume allowance for all the grounds combined, based on the largest grounding conductor. So if you have two 14 AWG, five 12 AWG and one 10 AWG, then we would take a 2.5 cubic inch volume addition based on the 10 AWG grounding conductor.

Box fill calculations is one of the most basic items for inspectors; yet for years, I have seen inspectors just walk by these violations, either due to their ignorance of the code or they just dont consider it important. If youve ever been an electrician and had to do service work in a box that was overfilled, it would convince you that this code requirement should not be taken lightly. A little trick I would use if I found a box overfilled during inspections would be to take out a writing utensil and just do the calculation on the face of the stud. For example: five 12 AWG = 11.25; 2 devices = 9; 12 AWG ground = 2.25; then I would total it 22.5. I would then write the violation on my ticket, such as "overfilled box, end of hallway switch, see calculation on stud.” To this day, contractors remember this practice and have mentioned it to me.

The next item for combination inspectors would be 314.20, which deals with the box mounting details. If you have boxes in non-combustible surfaces such as concrete, tile, gypsum, or plaster, the box must be installed so that the front edge of the box is no more than ¼ inch back of the surface. This can be quite a challenge, and is often not enforced nearly as well as it should be. If you are dealing with combustible surfaces, like wood, then the boxes have to be totally flush or project past the surface. As I said, it is a challenge to get the ¼ inch, so perfectly flush is even more of a task. The concept here is that if for some reason we have an arcing event inside a box, we absolutely do not want to ignite anything outside the box. If we maintain this code requirement, we minimize the possibilities of a dangerous condition while we are waiting for the overcurrent devices to operate. In 314.21, the code addresses repairing noncombustible surfaces where we have a gap or open space larger than ⅛ inch at the edge of the box.

Please review 314.23, Supports, on your own. One piece of advice I would offer when inspecting for these items is to take a closer look if the mounting of a box does not look like a nice clean installation. I have seen people violate the UL listing of many boxes by just drilling holes into the interior sides of the boxes, and installing nails or screws to mount them in ways that are not tested and approved. There always seems to be an inventive installer who just doesnt have exactly the right box for the application, so in an effort to "get the job done” the installer creates code enforcement headaches which then result in contractor headaches.

Section 314.24, Depth of Boxes, seems like it would be a basic requirement. However, as I mentioned before, in today’s environment of ever more sophisticated control devices that are getting larger in size, we must allow for increased depth. Part of 314.24(B)(1) addresses this: where the devices are deeper than 1-⅞″, then the box to mount these in must have a depth at least ¼″ deeper than the device. Also in (B)(3), (4) and (5), you will find minimum depths for boxes in relation to the conductors being used.

Section 314.27, Outlet Boxes, starts with (A), which covers boxes used for mounting luminaires. Let’s think about this for a while. We are typically not concerned about the support capabilities of boxes that are used just for devices, such as switches and receptacles. However, when it comes to luminaires that at times can weigh several hundred pounds, we must give the support capability some consideration. If we have a wall-mounted box, it must be listed for the weight permitted to be supported by the box alone, if it is other than 50 pounds. A similar requirement applies to ceiling light boxes. If the luminaire weighs more than 50 pounds, then that luminaire shall be independently supported by some means other than the box alone, unless the box is listed and marked to support at least the actual weight of the luminaire.

Floor boxes must be listed specifically for the use when installing receptacles in the floor. I have seen attempts to use normal wall boxes as floor boxes a few times; however, the use of devices and boxes in the floor are subject to more abuse and special conditions that must be considered during the design and listing stages. Make sure these are properly listed as floor boxes and are installed in accordance with the manufacturer’s instructions.

Ceiling-Suspended (Paddle) Fan Outlet boxes must also meet some special requirements. Some of the unique concerns here (besides weight) are the vibration and oscillation of the fan. Therefore, boxes need to be listed and labeled for the purpose. Please review 314.27(C) for the exact details related to the weight limits and marking requirements for ceiling fan boxes.

The last part of Article 314 we are going to cover is 314.28, Pull and Junction Boxes and Conduit Bodies. First, the language tells us that the minimum size requirements only apply to installations where the raceways entering the junction box or conduit body contain conductors 4 AWG or larger. So how do we size these boxes? In (A)(1), (2), and (3) we find the rules for sizing. If you have a straight pull, meaning the conduit(s) enter one wall and exit the opposite wall, then we use (A)(1). This gives us a simple method to size the box: it must have a dimension from one side to the other that is 8 times the size of the largest raceway coming into the box. So if it is a 3 inch conduit, then the minimum length for the box would be 24 inches. These are often used as pulling points in long conduit runs and you must have some working distance within these boxes for pulling and feeding these larger conductors.

Where we have angle or U pulls or splices within a pull or junction box, the size varies for the above. Here we take the size of the largest conduit and multiply it by six, and then add the sum of the rest of the conduits in the same row in the same wall; this will give you the minimum distance to the opposite wall of the junction box. If you have multiple rows then you calculate each row and use the largest number. So if you have a 4-inch, two 2-inch and five 1-inch conduits, you would take 6 times 4 = 24 plus 9 for a total minimum distance of 33 inches, which you cant normally find, so you would settle on a 36-inch junction box.

In 314.28(E), the code covers power distribution blocks installed within these boxes. First, the power distribution block must be listed. Second, if it has a minimum box size required in the installation requirements that exceeds the size required by the code, you must use the larger size. The last two items to be aware of for power distribution blocks include proper wire bending space for the terminations as required by 312.6 and that uninsulated parts must not be exposed, so they must have some type of covering or be finger safe.

This article only hit the high points in Articles 312 and 314, so don’t forget to read both articles in their entirety so you have some familiarity with what is in the Code. In the next article, we will begin discussing the wiring methods in Chapter 3.


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Hazardous Location — How do we know that it actually is?

Posted By Ark Tsisserev, Wednesday, January 15, 2014

The experience of dealing with this subject demonstrates lots of inconsistencies among the designers, installers and regulators. And the issue relates not only to a proper selection of electrical equipment and wiring methods for connection of this equipment, but to the determination of hazard and to the ability of accurately assigning specific area of classification for a particular hazardous location.

Of course, the essence of this discussion is based on the provisions of the Canadian Electrical Code on this subject.

 

Photo 1. Three-car residential parking garage is non-hazardous location from the CE Code perspective.

Perhaps, use of a few examples would be appropriate. Let say, you decide to build a house with a 3-car garage where vehicles that use volatile flammable liquids or flammable gases are stored. Does such garage become a hazardous location in accordance with the CE Code? And what about a small woodworking shop in a high school? And how about a boutique distillery that is set up in a typical rental unit of an industrial building? And what about an area where a diesel fueled generator is located with the fuel storage tank? And what about locations where gasoline or other similar volatile flammable liquids are stored in tanks, or locations where paints, lacquers, or other flammable finishes are regularly or frequently applied by spraying, dipping, brushing, or by other means, and where volatile flammable solvents or thinners are used? And what about a typical grain handling or sugar pulverizing plant? Or how about locations with textile mills, flax processing plants; or clothing manufacturing plants?

Examples of such locations with various industrial processes or with storages of flammable or combustible liquids are numerous. Does each such area have to be classified as "hazardous location” in accordance with the CE Code?

To answer these questions, we might want to start with the Code definition of hazardous location. It is defined as follows:

"Hazardous location (see Appendix B) — premises, buildings, or parts thereof in which

(a) an explosive gas atmosphere is present, or may be present, in the air in quantities that require special precautions for the construction, installation, and use of electrical equipment;

(b) combustible dusts are present, or may be present, in the form of clouds or layers in quantities to require special precautions for the construction, installation, and operation of electrical equipment; or

(c) combustible fibres or flyings are manufactured, handled, or stored in a manner that will require special precautions for the construction, installation, and operation of electrical equipment.”

 

Photo 2. Paint spraying is Class I hazardous location.

Appendix B Note on this definition provides the following clarification:

"Hazardous location

In this definition, "special precautions” refers to the special features of electrical equipment design, installation, and use that are intended to prevent the equipment from igniting flammable vapours, dust, fibres, or flyings. See Section 18 for more specific requirements on hazardous locations.”

Now, it is the appropriate time to visit Section 18 of the CE Code. Scope of Section 18 indicates that this Section applies to locations in which electrical equipment and wiring are subject to the conditions indicated by classifications of types of hazard. The scope of Section 18 also statesthat this Section supplements or amends the general requirements of the CE Code. This means that provisions of Section 18 are additional to the general requirements of the electrical installation Code and in some cases — are different from the general rules of the Code. Such additional or different provisions have been introduced in Section 18 — in order to address specific safety concerns in respect to the installation of equipment and wiring methods in hazardous locations.


Photo 3. Gasoline dispensing and service station is Class I hazardous location. 

Rules 18-004 – 18-010 of the CE Code provide a clear criteria for classification of particular hazardous locations – by identifying Classes of hazardous locations based on a potential for flammable gases or vapours being present in the air in quantitiessufficient to produce explosive gas atmospheres, or on a potential for existence of combustible or electrically conductive combustible dusts in the air, or on a possibility of easily ignitable fibres or flying in the air – to produce ignitable mixtures. These Rules further subdivide such identified Classes into specific Zones or Divisions. This precise fragmentation of each Class into a specifically identified Zone or Division becomes a fundamental criteria for selection of the appropriate electrical equipment and wiring methods for each type of hazardous location.

Only when any such potential for creating above highlighted hazardous conditions exists, such areas have to be classified as hazardous locations.

Let’s take a look on Subrule 18-004(a) and on Rule 18-006, which cover Class I hazardous location.

 

"18-004 Classification (see Appendix B)

Hazardous locations shall be classified according to the nature of the hazard, as follows:

(a) Class I locations are those in which flammable gases or vapours are or may be present in the air in quantities sufficient to produce explosive gas atmospheres;”

 

Photo 4. Propane storage is Class I hazardous location. 

"18-006 Division of Class I locations (see Appendices B and J)

Class I locations shall be further divided into three Zones based upon frequency of occurrence and duration of an explosive gas atmosphere as follows:

(a) Zone 0, consisting of Class I locations in which explosive gas atmospheres are present continuously or are present for long periods;

(b) Zone 1, consisting of Class I locations in which

(i) explosive gas atmospheres are likely to occur in normal operation; or

(ii) the location is adjacent to a Class I, Zone 0 location, from which explosive gas atmospheres could be communicated; and

(c) Zone 2, consisting of Class I locations in which

(i) explosive gas atmospheres are not likely to occur in normal operation and, if they do occur, they will exist for a short time only; or

(ii) the location is adjacent to a Class I, Zone 1 location, from which explosive gas atmospheres could be communicated, unless such communication is prevented by adequate positive-pressure ventilation”

Appendix B Note on Rule 18-006 provides the Code users with a very important clarification on the criteria for identification of Zones of Class I Location as follows:

 

Photo 5. Combustible dust environment is Class II hazardous location.

"Rule 18-006

Typical situations leading to a Zone 0 area classification are

(a) the interiors of storage tanks that are vented to atmosphere and that contain flammable liquids stored above their flash point;

(b) enclosed sumps containing flammable liquids stored above their flash point continuously or for long

periods; and

(c) the area immediately around atmospheric vents that are venting from a Zone 0 hazardous area.

Typical situations requiring a Class I, Zone 1 hazardous locations are

(a) inadequately ventilated buildings or enclosures;

(b) adequately ventilated buildings or enclosures, such as remote unattended and unmonitored facilities, that have insufficient means of limiting the duration of explosive gas atmospheres when they do occur; and

(c) enclosed sumps containing flammable liquids stored above their flash point during normal operation.

 

Typical situations leading to a Zone 2 area classification are

(a) areas where flammable volatile liquids, flammable gases, or vapours are handled, processed, or used, but in which liquids, gases, or vapours are normally confined within closed containers or closed systems from which they can escape only as a result of accidental rupture or breakdown of the containers or systems or the abnormal operation of the equipment by which the liquids or gases are handled, processed, or used;

(b) adequately ventilated buildings that have means of ensuring that the length of time where abnormal operation resulting in the occurrence of explosive gas atmospheres exist will be limited to a "short time”; and

(c) most outdoor areas, except those around open vents, or open vessels or sumps containing flammable liquids.”

Subrule 18-004(b) and Rule 18-008 cover Class II location and Divisions of this hazardous location Class based on the conditions of presence of combustible dust in the air as follows.

"Rule 18-004(b) Class II locations are those that are hazardous because of the presence of combustible or electrically conductive combustible dusts”;

"18-008 Division of Class II locations (see Appendix B)

Class II locations shall be further divided into two Divisions as follows:

(a) Division 1, consisting of Class II locations in which

(i) combustible dust is or may be in suspension in air continuously, intermittently, or periodically under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures;

(ii) the abnormal operation or failure of equipment might

(A) cause explosive or ignitable mixtures to be produced; and

(B) provide a source of ignition through simultaneous failure of electrical equipment, operation of protection devices, or from other causes; or

(iii) combustible dusts having the property of conducting electricity may be present; and

(b) Division 2, consisting of Class II locations in which

(i) combustible dust may be in suspension in the air as a result of infrequent malfunctioning of handling or processing equipment, but such dust would be present in quantities insufficient to

(A) interfere with the normal operation of electrical or other equipment; and

(B) produce explosive or ignitable mixtures, except for short periods of time; or

(ii) combustible dust accumulations on, in, or in the vicinity of the electrical equipment, may be sufficient to interfere with the safe dissipation of heat from electrical equipment or may be ignitable by abnormal operation or failure of electrical equipment.”

Appendix B Note on Rule 18-008 explains the intent of this Rule in details for the benefit of the Code users as follows:

"Rule 18-008

Class II, Division 1 locations usually include the working areas of grain-handling and storage plants; rooms containing grinders or pulverisers, cleaners, graders, scalpers, open conveyors or spouts, open bins or hoppers, mixers or blenders, automatic or hopper scales, packing machinery, elevator heads and boots, stock distributors, dust and stock collectors (except all-metal collectors vented to the outside), and all similar dust-producing machinery and equipment in grain processing plants, starch plants, sugar pulverizing plants, malting plants, hay grinding plants, and other occupancies of similar nature; coal pulverizing plants (except where the pulverizing equipment is essentially dust-tight); all working areas where metal dusts and powders are produced, processed, handled, packed, or stored (except in tight containers); and all other similar locations where combustible dust may, under normal operating conditions, be present in the air in quantities sufficient to produce explosive or ignitable mixtures.

Combustible dusts that are electrically non-conducting will include dusts produced in the handling and processing of grain and grain products, pulverized sugar and cocoa, dried egg and milk powders, pulverized spices, starch and pastes, potato and wood flour, oil meal from beans and seed, dried hay, and other organic materials that may produce combustible dusts when processed or handled. Only Group E dusts are considered electrically conductive for the purposes of classification. Metallic dusts of magnesium, aluminum, and aluminum bronze are particularly hazardous, and every precaution should be taken to avoid ignition and explosion.

Class II, Division 2 locations include those in which dangerous concentrations of suspended dust are not likely, but where dust accumulation might form on, in, or in the vicinity of electrical equipment, and include rooms and areas containing only closed spouting and conveyors, closed bins or hoppers, or machines and equipment from which appreciable quantities of dust might escape only under abnormal conditions; rooms or areas adjacent to Class II, Division 1 locations and into which explosive or ignitable concentrations of suspended dust might be communicated only under abnormal operating conditions; rooms or areas where the formulation of explosive or ignitable concentrations of suspended dust is prevented by the operation of effective dust control equipment; warehouses and shipping rooms in which dust-producing materials are stored or handled only in bags or containers; and other similar locations.

There are many dusts, such as fine sulphur dust, that cannot be equated specifically to dusts mentioned above, and in a number of cases further information may be obtained by reference to Standards included in the NFPA National Fire Codes; for example, NFPA 655 gives information on prevention of sulphur fires and explosions and makes reference to electrical wiring and equipment.”

And, finally, Subrule 18-004(c) and Rule 18-010 deal with the criteria for identifying Class III location and appropriate Divisions of Class III location as follows:

"18-004(c) Class III locations are those that are hazardous because of the presence of easily ignitable fibres or flyings, but in which such fibres or flyings are not likely to be in suspension in air in quantities sufficient to produce ignitable mixtures.”

 

"18-010 Division of Class III locations (see Appendix B)

Class III locations shall be further divided into two Divisions as follows:

(a) Division 1, consisting of Class III locations in which readily ignitable fibres or materials producing combustible flyings are handled, manufactured, or used; and

(b) Division 2, consisting of Class III locations in which readily ignitable fibres other than those in process of manufacture are stored or handled.”

Appendix B Note on Rule 18-010 provides necessary clarifications in respect to Class III Locations.

"Rule 18-010

Class III, Division 1 locations include parts of rayon, cotton, and other textile mills; combustible fibre manufacturing and processing plants; cotton gins and cotton-seed mills; flax processing plants; clothing manufacturing plants; woodworking plants; and establishments and industries involving similar hazardous processes or conditions.

Readily ignitable fibres and flyings include rayon, cotton (including cotton linters and cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fibre, oakum, baled waste, kapok, Spanish moss, excelsior, and other materials of similar nature.”

Of course, these Code selection criteria for the appropriate hazardous locations (and explanatory Notes in Appendix B) are very helpful to the users. However, practice has demonstrated that the electrical designers, installers and regulators are not necessarily the ultimate experts of various processes associated with potential for flammable gases or vapours being present in the air in quantities sufficient to produce explosive gas atmospheres, or on a potential for existence of combustible or electrically conductive combustible dusts in the air, or on a possibility of easily ignitable fibres or flying in the air – to produce ignitable mixtures.

As such, their ability to accurately determine the most appropriate area of classification could be limited without additional information contained in the National Fire Code of Canada (NFCC) and certain NFPA standards. For example, Part 4 of the NFCC deals with Properties of Flammable and Combustible Liquids; NFPA 497 covers Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, etc.

 

Photo 6. Grain handling is Class II hazardous location.

The CSA is considering to develop a guide which will help the Canadian Electrical Code users to determine areas of classification with a much better accuracy. Meanwhile, the electrical Code users have to seek assistance from the process specialists, in order to evaluate locations and processes for a need to properly select electrical equipment and wiring in the areas that are deemed to be hazardous locations in accordance with the CE Code.

After reviewing the referenced rules of Section 18 of the CE Code, the readers may be able to confirm that a 3-car attached garage of a dwelling is not considered as a hazardous location.

Similarly, an area that contains a diesel fueled generator also should not be considered as a Class I hazardous location (diesel is not a flammable fuel). And, certainly, some areas in a typical distillery must be treated as Class I locations. Of course, areas containing a paint spray operation or dispensing or storage of gasoline or compressed gas would represent Class I locations. Similarly, sugar pulverizing and grain handling facility would be classified as Class II location, and a woodworking shop, textile mill or a flax processing plant might have to be classified as Class III location, unless it could be demonstrated that readily ignitable fibres will not be present in the air, as a result of operation of a dust collection system.

 

Photo 7. Cotton mill is Class III hazardous location.

There could be, however, certain conditions where no specific equipment suitable for the purpose is available. In this case, Rule 18-070 allows installation of electrical equipment suitable for non-hazardous locations — in a Class I, Zone 2 hazardous location and electrical equipment suitable for Class I, Zone 2 hazardous locations — in a Class I, Zone 1 hazardous location, but such relaxation is allowed by this Rule of the Code under very stringent conditions as follows:

"the equipment, during its normal operation, does not produce arcs, sparks, or hot surfaces, capable of igniting an explosive gas atmosphere; and the location is continuously monitored by a combustible gas detection system that will

(i) activate an alarm when the gas concentration reaches 20% of the lower explosive limit;

(ii) activate ventilating equipment or other means designed to prevent the concentration of gas from reaching the lower explosive limit when the gas concentration reaches 20% of the lower explosive limit, where such ventilating equipment or other means is provided;

(iii) automatically de-energize the electrical equipment being protected when the gas concentration reaches 40% of the lower explosive limit, where the ventilating equipment or other means referred to in Item (ii) is provided;

(iv) automatically de-energize the electrical equipment being protected when the gas concentration reaches 20% of the lower explosive limit, where the ventilating equipment or other means referred to in Item (ii) cannot be provided; and

(v) automatically de-energize the electrical equipment being protected upon failure of the gas detection instrument.

 

The Code users should be aware that the relaxation to apply the less restrictive provisions for electrical equipment (i.e., equipment suitable for non-hazardous locations, when it is installed in Class I, Zone 2 location, etc.) by no means allows re-classification of the originally determined hazardous area.

Thus, if (as shown in example above), "the equipment suitable for non-hazardous area is allowed to be installed in Class I, Zone 2 hazardous location under conditions of Rule 18-070, the area of classification still remains Class I, Zone 2.”

However, as usual, all issues related to the electrical design and installations should be discussed with the local AHJs that administer the Canadian Electrical Code in the area of the intended design and installation.


Read more by Ark Tsisserev

Tags:  Featured  January-February 2014 

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