Posted By Underwriters Laboratories,
Monday, September 16, 2013
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In the process of pulling THHN conductors through raceway we encountered some scuffing and scraping of the outer nylon conductor covering at the final fitting. The engineer says we ruined the conductor and wants it replaced. Does damage to the nylon covering constitute damage to the conductor insulation?
A Type THHN wire is comprised of three basic parts, the conductor, PVC insulation, and a nylon jacket. Each part has a specific use. Damage to the nylon jacket only, does not constitute damage to the insulation. The nylon jacket does provide mechanical protection to the insulation during and after installation and also provides gasoline and oil resistance for the wire. The question concerning replacement of the damaged wire can only be answered by visually examining the wire to understand the extent of the damage; and if the PVC insulation is damaged, or if the conductor is exposed to gas and oil, then replacing the wire may be necessary.
UL certifies (Lists) THHN conductors under the product category Thermoplastic- Insulated Conductors (ZLGR), located on page 491 of the 2013 UL White Book and can also be found in UL’s Online Certification Directory at www.ul.com/database and enter ZLGR at the category code search field.
THHN conductors that are certified (Listed) under (ZLGR) are evaluated for compliance with the Standard for Safety for Thermoplastic-Insulated Wires and Cables, UL 83. UL 83 requires THHN conductors to be provided with a nylon jacket extruded tightly over the insulation with a minimum thickness of 4 mils for 14-10 AWG conductors and thicker for larger conductors.
Is there a PDF download available of the 2013 UL White Book?
Yes, the 2013 version has been improved and is more user friendly and intuitive providing linked navigation embedded into the document for ease of use and with an internet connection, direct access to Code-complaint UL Certified products. The Linked version of the 2013 UL White Book PDF is now posted at www.ul.com/whitebook just click on the banner on the right side of the page.
What does a "linked version” mean? The Table of Contents (TOC) and the Indexes of the UL Product Categories Correlated to the 2008 and 2011 NEC are all linked so that if you click on any TOC entry; or the page number or the category code in the NEC Indexes, it will link you to that page in the file/book. In addition, each of the product category titles in the book (that are not main product categories without any certifications) will link to all the UL Certifications for the product category in the UL Online Certification Directory at www.ul.com/database. This will provide you the proper categories for each code section and then the certifications for those categories, giving the user direct access to code-compliant products.
The links in the pdf will also work on iPads and iPhones by opening and using the file in Drop Box. If you save it directly to your Apple device outside of Drop Box, the links will not work and it will be a regular pdf file. The links in the pdf do not work on Android devices, even if opening in Drop Box. It will just be a regular pdf.
Drop Box is a free application that allows you to share files between all your devices and can be downloaded for free at www.dropbox.com.
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UL Question Corner
Posted By Hugh Hoagland,
Monday, September 16, 2013
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The 90-year-old technology of using rubber
gloves for shock and leather gloves for protection of the rubber soon
could be turned on its head by innovation.
For years, we have
heard the question, "What about gloves in arc flash?” The reason this question
wasn’t answered sooner is complicated, but the standard is now available. ASTM
F2675-13, Test Method For Determining Arc Ratings of Hand Protective
Products Developed and Used for Electrical Arc Flash Protection, is an ASTM
International standard with an approval date of June 1, 2013, that was expected
to be published by ASTM International within the month of July. Testing is
progressing already, with more than 25 types of gloves tested in the past few
years, now having a specific standard to target.
Gloves meeting this standard may not be designed for
shock. Only ASTM D120-compliant gloves are currently approved for use for
protection from shock, but some ASTM D120 gloves, all of which are made of
rubber, have been tested by this method and could begin to be labeled as such
in the near future for the information of the end user. The method, however,
really was designed for protection from arc flash only, thus the title.
ASTM D120 gloves
on the market today are made only of
rubber and are primarily for shock protection, though historically, they have
been covered with an ASTM F696 leather protector glove and provide excellent
arc-flash protection. The rubber gloves, however, can ignite in arc flash, so a
small contingent of the ASTM F18 committee wanted them excluded from the required
testing to avoid a possible legal requirement that could not be met. However,
rubber gloves that have been tested have shown a strong performance in this arc
test method, and certain additives could make them even more flame-resistant in
the future. Research is ongoing, but some suppliers plan to label their D120
gloves with F2675 arc ratings and ignition values. Check to see if your
supplier has data. Different colors will have different results; and the results,
to date, have varied between suppliers even with the same colors because the
colors are formulated with different additives to achieve the color.
Photo 2. Rubber gloves with leather protectors are quite protective from arc flashes. New technologies might make them more flexible and offer a better grip.
Photo 3. A new leather protector has patented "grip strips” developed by a Canadian lineman. It also has a 40 cal/cm² arc rating
Advantages for End Users and Manufacturers
So if this standard is for arc-flash gloves
that might not meet ASTM D120 for shock, what good are they? The gloves are
useful for arc flash as work gloves. If your hazard assessment for an
electrical task includes a shock hazard, ASTM D120 gloves are still your only
option, with or without a leather protector (see OSHA, NFPA 70E, and ASTM F496
requirements for protector gloves).
Uses for arc flash gloves include the following:
1. "Heavy duty leather gloves” for arc-flash
protection (NFPA 70E-2012, Standard for Electrical Safety in the Workplace,
required these for several jobs without shock hazards). But because there was
no arc flash test method for gloves, the committee had to make the gloves of a
certain thickness. Now, the gloves could be made thinner and still meet minimum
protection for the hazard.
2. To replace "heavy duty leather work gloves” when
they are inadequate for other multiple threats. Non-leather gloves are being
worn in more workplaces today. Non-leather specialty gloves that grip when wet
or oily can be engineered to make the gloves more task-specific and
ergonomically designed. Now, these gloves also can be arc-rated so that a
machine operator who is operating a disconnect will have no need to change
gloves when the tables are used for arc-flash hazard assessment but needs a
3. The NFPA 70E Table 130.7(C)(15)(a) Hazard/Risk
Category Classifications and Use of Rubber Insulating Gloves and Insulated and
Insulating Hand Tools-Alternating Current Equipment and 130.7(C)(15)(b) for
DC Equipment require "arc-rated gloves” or D120 gloves with F696 leather
protectors for certain tasks. Now, there will be "arc-rated gloves” for the
non-shock hazard tasks that have arc flash potential.
4. The additional option the ASTM F18 committee is
working on now is to allow OSHA-required (1910.137) "protector gloves” to be
something other than leather. The 90-year-old technology of using rubber gloves
for shock and leather gloves for protection of the rubber soon could be turned
on its head by innovation because the cut standards, puncture standards, and
now arc-flash standards for gloves are in place to specify new options to
protect workers from shock and arc flash while making gloves lighter, thinner,
and giving a better grip.
A new glove on the market from Canada is an ASTM F696
leather glove with a patented added polymer strip on part of the palm, making
the leather protector glove have improved grip when oily or wet. This was
developed by a lineman in Canada and tested for arc flash last year. It is a
potential game changer for protectors. Watch for other innovative designs in
protectors soon, now that a performance based test method is available.
mentions "protector gloves” in the standards but doesn’t call them "leather”
(though F696 is listed in the standard as acceptable), it is possible we could
see knit "protector gloves” being adopted for low voltage within the year. What
other options could we see with test methods to test for real product
performance? Could we have other improvements in safety equipment for arc flash?
Testing has been driving innovation for several years, so expect change for the
Photo 4: Traditional leather protectors provide puncture, cut and arc flash protection but with this new standard the bar may be raised to allow materials other than leather to be protector gloves with better cut, puncture and even better arc protection in a thinner package. The possibility is now there.
Caution: When selecting gloves for arc flash
exposures, two considerations must be followed:
1. Assess the hazard for shock first. If shock
hazards exist, use an ASTM D120 rubber insulating glove under the arc flash
protector glove and properly match the length of the rubber to be the proper
length for the protector gloves. Most companies choose ASTM D696 leather
protectors. Additionally, the protector must be shorter than the rubber glove
by a distance set in ASTM F496.
2. Assess the arc flash hazard from a realistic
distance from the hazard. Most arc flash calculations are for a working
distance of 18–36 inches. The hands may well be closer, and this should be
considered in the hazard assessment.
Could arc flash crossover, multi-threat gloves for cut, chemical, and arc
flash protection be something to consider to update your safety program? Stay
tuned as these glove choices increase in the near future.
Hugh Hoagland is senior managing partner of
e-Hazard.com, a leading provider of arc flash and electrical safety training,
and senior consultant at ArcWear.com, the leading testing company for arc rated
materials and PPE.
Hand Protection -- Occupational Health & Safety,
http://ohsonline.com/articles/list/ht-hand-protection.aspx (accessed August 21,
This article was
published in the August 2013 issue of Occupational Health & Safety magazine.
©1105 Media Inc. Reprinted by permission from 1105 Media.
Posted By Steve Foran,
Monday, September 16, 2013
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Over the last few weeks I have been on the receiving end of unprecedented levels of customer service — at both extremes of the spectrum. The four quick incidents that follow all happened during a weekend away with some old friends.
First, being asked what we wanted for dinner in a restaurant as the waitress was swallowing food herself, and then she was eating pie at the register as we paid our bills. Second, at another meal one of my mates was patted on the back and told, "Finish it off,” instead of asked, "How is your meal?” The fact that he ate less than half of what was on his plate should have been a signal.
On a positive note, for the third incident we had a corner store owner almost do back flips to serve up a bag of ice and two ice cream cones. She was pleasant, talkative, and interested in us. She made us want to come back. And to wrap it up, when we asked the concierge at the resort to point us to our cabins, she explained very politely why she does not point and gestured using four fingers and an open hand. We felt like we learned a universal truth.
In each of these cases, what would prompt someone to act that way?
There are many reasons we could presuppose, all of which are superficial. For the mediocre servers, maybe their boss does not care, or they do not understand the importance of their job, or they do not have the proper training. I do not know.
As for the great servers, perhaps we caught them on a good day, or they are jazzed up about helping others, or they have an incentive to provide great service. Again, I am not sure why.
Regardless, there is one underlying reason that explains the difference between excellent service and mediocre service. The root cause rests in how the server thinks about his or her work.
For people who provide excellent service, they care. They care about the work they do and the customers they serve. For the people who provide mediocre service, quite simply they do not care.
Who knows why these individuals cared or not, but fortunately there is a cure for not caring. There is a feeling, that when elicited, is guaranteed to help people care more. It is the missing link to caring, as well as to excellent service and happy people. It is simple and it will transform someone who does not care into someone who cares.
The missing link is gratitude and you can help someone experience it by asking the question, "What are you grateful for about your work?”
Be patient and listen. Resist the temptation to tell them what they should be grateful for. If they continue having difficulty in finding something to be grateful for, then share what you are grateful for. Be open and honest. Then ask them the question again.
Once someone is genuinely grateful, they cannot help but care. They will seek out solutions to the superficial reasons like lack of training. As a result, they will be happier and the customers they serve will be happier too. Remember, this is not a "bucket list” question. It is a question that must be asked over and over again so that caring and excellent service do not become flavors of the month.
There is one caveat. If you want this technique to work with others, first you must be genuinely grateful and you must care. So make sure you have a good sense of what you are grateful for concerning what you do and those you serve. If someone senses that you are not genuine in how you express your gratitude or your care, the question just might backfire on you.
Read more by Steve Foran
Posted By Ark Tsisserev,
Monday, September 16, 2013
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The subject of fire protection of electrical conductors appears to create some confusion in the industry, and this article attempts to clarify provisions of the National Building Code of Canada (NBCC 2010) in this regard.
Subsection 3.2.7. of the NBCC mandates emergency power for specific systems and equipment that must continue to function in the event that a regular power to these systems and equipment is interrupted.
These specific systems and equipment are defined in Section 46 of the CE Code as "Life safety systems” as follows: "Life safety systems — emergency lighting and fire alarm systems that are required to be provided with an emergency power supply from batteries, generators, or a combination thereof, and electrical equipment for building services such as fire pumps, elevators, smoke-venting fans, smoke control fans, and dampers that are required to be provided with an emergency power supply by an emergency generator in conformance with the National Building Code of Canada.”
Articles 22.214.171.124. and 126.96.36.199. of the NBCC state that for emergency lighting and for fire alarm systems (including voice communication where voice communication is required to be provided as a part of a fire alarm system by Article 188.8.131.52.), such emergency power source could be represented by batteries or generators. These NBCC articles further specify a minimum period of time during which such power supply sources must automatically supply the connected loads. This minimum required period varies from 5 minutes for a building allowed by the NBCC to be equipped with a single zone fire alarm system up to 2 hours, where such systems and equipment are installed in a high building.
Photo 1. Building exhaust fan system
Although Articles 184.108.40.206. and 220.127.116.11. of the NBCC allow an option of using batteries or emergency generators as the emergency power supply source for emergency lighting and fire alarm systems, Sentence 18.104.22.168.(1) of the NBCC specifically mandates use of an emergency generator capable to operate under a full load for not less than 2 hours as an emergency power supply source for a very particular life safety equipment as follows:
"22.214.171.124. Emergency Power for Building Services
(1) An emergency power supply capable of operating under a full load for not less than 2 h shall be provided by an emergency generator for
a) every elevator serving storeys above the first storey in a building that is more than 36 m high measured between grade and the floor level of the top storey and every elevator for firefighters in conformance with Sentence (2),
b) water supply for firefighting in conformance with Article 126.96.36.199., if the supply is dependent on electrical power supplied to the building,
c) fans and other electrical equipment that are installed to maintain the air quality specified in Article 188.8.131.52.,
d) fans required for venting by Article 184.108.40.206., and
e) fans required by Clause 220.127.116.11.(1)(c) and Article 18.104.22.168. in buildings within the scope of Subsection 3.2.6”.
The NBCC also mandates protection of certain electrical conductors supplying power to the equipment that is identified as part of "Life safety systems” (i.e., of conductors that supply power to the equipment required to be provided by the NBCC with the emergency power supply) and protection of certain electrical conductors supplying power to the equipment that is not specifically identified as part of "Life safety system.”
Thus, the subject of protection of conductors against exposure to fire has generated some confusion in respect to the following:
1. Conductors supplying what equipment should be protected? (i.e., does the NBCC requirement include conductors supplying power to mechanical exhaust systems — to remove air from interconnected floor spaces, conductors supplying power to lifts for disabled persons in low and high buildings, conductors supplying every elevator in a high building, conductors supplying a make-up or exhaust air handling systems in low and high buildings, etc.?)
2. What is the extent of the required fire protection of conductors? (i.e., are these conductors required to be protected from the normal or emergency supply, to the equipment being served or to the last distribution panel supplying such equipment, to the devices of a fire alarm system located on a floor, etc.?)
3. What are the means to provide protection of conductors against exposure to fire (i.e., are these conductors required to be enclosed in a shaft enclosure of at least 2 h fire resistance construction, or to be provided with a minimum cover over the raceway of at least 100 mm in concrete, floor slabs or walls that form part of fire separations, or to be circuit integrity cables that conform to the ULC S139 circuit integrity test and that are marked "CIR ULC S139 2 h” in addition to a certification monogram?).
4. Whether such fire protection of conductors is, in fact, required for 1 h or for 2 h?
The following discussion and conclusion on this subject intends to clarify this subject.
Article 22.214.171.124. of the NBCC mandates protection of conductors against exposure to fire as follows:
"126.96.36.199.Protection of Electrical Conductors
1) The protection of electrical and emergency conductors referred to in Clauses (a) to (c) shall conform to the requirements stated in Sentences (2) to (8):
a) electrical conductors located within buildings identified in Article 188.8.131.52. serving
i) fire alarms,
ii) emergency lighting, or
iii) emergency equipment within the scope of Articles 184.108.40.206. to 220.127.116.11.,
b) emergency conductors serving fire pumps required to be installed under Article 18.104.22.168., and
c) electrical conductors serving mechanical systems serving
i) areas of refuge identified in Clause 22.214.171.124.(1)(b), or
ii) contained use areas identified in Clauses 126.96.36.199.(4)(a) and (b).
2) Except as otherwise required by Sentence (3) and permitted by this Article, electrical conductors that are used in conjunction with systems identified in Sentence (1) shall
a) conform to ULC-S139, "Fire Test for Evaluation of Integrity of Electrical Cables,” including the hose stream application, to provide a circuit integrity rating of not less than 1 h, or
b) be located in a service space that is separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 1 h.
3) Electrical conductors identified in Clause (1)(c) shall
a) conform to ULC-S139, "Fire Test for Evaluation of Integrity of Electrical Cables,” including the hose stream application, to provide a circuit integrity rating of not less than 2 h, or
b) be located in a service space that is separated from the remainder of the building by a fire separation that has a fire-resistance rating not less than 2 h.
4) The service spaces referred to in Clauses (2)(b) and (3)(b) shall not contain any combustible materials other than the conductors being protected.
5) Except as stated in Sentences (7) and (9), the electrical conductors referred to in Sentence (1) are those that extend from the source of emergency power to
a) the equipment served, or
b) the distribution equipment supplying power to the equipment served, if both are in the same room (see Appendix A).
6) If a fire alarm transponder or annunciator in one fire compartment is connected to a central processing unit or another transponder or annunciator located in a different fire compartment, the electrical conductors connecting them shall be protected in accordance with Sentence (2).
7) Fire alarm system branch circuits within a storey that connect transponders and individual devices need not conform to Sentence (2). (See Appendix A.)
8) Except as permitted in Sentence (9), if a distribution panel supplies power to emergency lighting, the power supply conductors leading up to the distribution panel shall be protected in accordance with Sentence (2).
9)Conductors leading from a distribution panel referred to in Sentence (8) to emergency lighting units in the same storey need not conform to Sentence (2)”
As it could be seen from this NBCC requirement, except for the conductors supplying electrically connected fire pumps required to be installed in any building (and not just in a high building), onlythe conductors that:
(a) supply life safety systems required to be provided with the emergency power supply (regardless of the source), and
(b) are installed in a high building, must be protected against exposure to fire for a period of not less than 1 h.
It could be also seen from this NBCC requirement that in accordance with Sentence (1)(c) above, conductors supplying such equipment as fans providing air supply to the area of refuge compartments that contain operating rooms, ICUs, delivery rooms or recovery rooms in a hospital, or conductors supplying pressurization fans required only in unsprinklered contained use areas of a jail [i.e., equipment that is not specifically identified as being a part of a "Life safety system” by the CE Code and that is not specifically listed by Sentence 188.8.131.52.(1) as being required to be provided with the emergency power supply by an emergency generator] must be protected against exposure to fire for a period of not less than 2 h. It should be noted that the requirement for an emergency generator in this case [as specified by Sentence 184.108.40.206.(1)(c) of the NBCC], would be mandated by Z32 or by the correctional facilities guidelines.
Sentence 220.127.116.11.(5) states that conductors supplying various equipment comprising "Life safety systems” and the equipment listed in Sentence (1)(c) must be protected from the source of the emergency power supply (i.e. from batteries or emergency generator) up to the equipment being served. This Sentence clarifies that only conductors supplying elevators in a high building that is more than 36 m high measured between grade and the floor level of the top storey – must be protected against exposure to fire, as only elevators in a building higher than 36 m are required by Article 18.104.22.168. to be provided with the emergency power. Sentences 22.214.171.124.(7) and (9) further clarify that fire protection of conductors connecting fire alarm system devices within a floor or conductors supplying a unit equipment for emergency lighting or remote lamps within a floor – is not necessary, and only "riser” conductors connecting transponders of a fire alarm system with a CACF or a CPU, or riser conductors supplying distribution panels for emergency lighting between floors must be protected against exposure to fire. It should be noted that although Sentence 126.96.36.199.(1) requires emergency power supply to be provided by an emergency generator for pressurization fans in vestibules serving interconnected floor spaces (see article 188.8.131.52.) in a high building, and for mechanical exhaust system – to remove air from an interconnected floor space (see Article 184.108.40.206.) in a high building, fire protection of conductors supplying this particular equipment does not appear to be listed by Article 220.127.116.11., and perhaps this omission was made by the NBCC writers by accident.
Thus, it is strongly recommended to provide fire protection of conductors supplying pressurization fans for vestibules serving an interconnected floor spaces and conductors supplying mechanical exhaust fans from interconnected floor spaces when such interconnected floor spaces are located in a high building.
Finally, it could be also seen from Article 18.104.22.168. that protection of conductors against exposure to fire could be accomplished by placing these conductors in service spaces with fire separation of the appropriate fire resistance rating (and if this option is selected, it must be discussed with the architects), or by specifying a circuit integrity cable that conforms to the fire test specified in the ULC standard S139. It should be noted that use of such circuit integrity cables is mandated not only by the NBCC, but by the CE Code, ULC S524, and by C282. It should be also noted that Rule 46-204 of the CE Code mandates such fire protection of conductors between an emergency generator and other components of the emergency power supply systems (i.e., transfer switch) when such components of the emergency power supply system are located in separate, not adjoining each other fire rated service rooms.
Electrical conductors between an emergency generator and the following electrical equipment installed in a high building must be protected against exposure to fire for a period not less than 1 h:
1. Pressurization/smoke control fans and dampers required in accordance with Sentence 22.214.171.124.(2) of the NBCC (to control smoke in exit stairs below grade);
2. Pressurization/smoke control fans and dampers required in accordance with Article 126.96.36.199. of the NBCC (in vestibules between a high building and any other building);
3. Every elevator serving storeys above the first storey and that is installed in a high building that exceeds36 m in building height and every fire fighter elevator in a high building;
4. Every exhaust fan installed in a high building and that is used as a smoke venting fan in accordance withArticle 188.8.131.52. of the NBCC (as venting means to aid firefighters);
5. Pressurization/smoke control fans and dampers required in accordance with Article 184.108.40.206. of the NBCC (in vestibules serving an interconnected floor space in a high building);
6. Mechanical exhaust system required in accordance with Article 220.127.116.11. of the NBCC (to remove air from an interconnected space in a high building).
Electrical conductors between an emergency generator and the following electrical equipment must be protected against exposure to fire for a period not less than 2 h (regardless whether it is a high building or not):
1. Pressurization fan installed in an area of refuge constructed in a hospital in accordance with Article 18.104.22.168. of the NBCC (in fire compartments that contain operating rooms, delivery rooms or ICUs).
2. Pressurization fan installed in a contained use area in accordance with Article 22.214.171.124. of the NBCC (in unsprinklered buildings only).
Electrical conductors between an emergency generator and each electrically connected fire pump - must be protected against exposure to fire for a period not less than 1 h (regardless whether it is a high building or not): Note: communication conductors between the generator and the transfer switches are also required to be protected against exposure to fire.
Electrical conductors between an emergency power supply source (from batteries or an emergency generator) and the following equipment installed in a high building must be protected against exposure to fire for a period not less than 1 h:
1. Fire alarm system control units (except for the control units provided with integral emergency power supply by means of batteries);
2. Fire alarm system transponders or annunciators;
3. Fire alarm system CACF;
4. Distribution panels supplying emergency lighting feeders and circuits to the emergency lighting/remote lamps located on various floors.
Notes: (a) riser conductors between FAS equipment indicated in items 1 – 3 above are also required to be protected against exposure to fire;
(b) fire alarm system conductors within a storey that connect transponders with individual devices and branch circuit conductors between a distribution panel that supply emergency lighting units or remote lights located in the same storey do not have to be protected against exposure to fire;
(c) communication conductors between the fire alarm system transponders, control units and CACF installed in different fire compartments of a high building are also required to be protected against exposure to fire.
Conductors that are deemed to be protected against exposure to fire by conforming to the ULC S139 fire test are the conductors that are marked: Circuit Integrity Rating (letters "CIR” 2 h ULCS139)
Note: A typical MI cable or other available circuit integrity cable on the market (i.e., "Draka,” Lifeline,” etc.) with the above referenced marking on the cable outer jacket is deemed to be considered as being protected against exposure to fire for 2 h in accordance with Clause 6.1A of ULC S139. Note: Electrical designers and electrical contractors may choose means of protection of electrical conductors against exposure to fire by placing these conductors in service spaces with the fire resistance rating of at least 1 h, and when such means of fire protection are selected, these means must be coordinated with the architects and general contractors accordingly.
And as usual, local authorities with jurisdictional power for enforcing protection of electrical conductors against exposure to fire must be consulted during the design and installation stages.
Read more by Ark Tsisserev
Posted By Jeff Greef,
Monday, September 16, 2013
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Most residential electrical services are not
designed to accept two sources of power, but they are often utilized for the purpose
of connecting PV systems in addition to utility power. NEC Article 705
provides accommodation for such connections, but sometimes these accommodations
cannot be used without replacing the service enclosure, or adding a distribution
panel, or making a supply-side connection, all of which entail additional cost.
Occasionally installers get "creative” by tapping directly into feeder
conductors coming off the service to a subpanel in the house. Article 705 is
silent on this specific method, and controversy exists as to whether it is a
compliant method at all. Jurisdictions must decide for themselves whether this
is compliant; and if they do allow it, examiners and inspectors must be aware
of how such an installation triggers the provisions of Article 705 which are
meant to prevent the overloading of conductors or busbars. This article
explores the specific issues encountered in such an installation.
For a broader treatment of NEC 705.12(D)
regarding requirements for making load-side connections for PV systems, see the
papers and articles on the subject written by John Wiles of the Institute for
Energy and the Environment at New Mexico State University. Those articles are
referred to at the end of this one. Mr. Wiles has written extensively on the
fundamental intent of 705.12(D). The focus of this article is how 705.12(D) comes
into play only in the case of a load-side tap. This specific issue brings the
fundamental intent of this code section to bear and so requires a brush up on
the basics of these provisions. See John Wiles’ article in the January-February
issue of IAEI magazine, "Unraveling the Mysterious 705.12(D) Load Side
PV Connections,” which demonstrates the basic intent of these provisions as
they pertain to connections at a load center bus bar with a breaker. Mr. Wiles’
article does not address the issue of tapping into feeders; however, the same
principles that come into play at bus bars with breakers also apply with
feeders and taps.
When a PV system is connected to a load center by a
breaker, the problem that can occur is overloading the busbars (see figure 1).
For example, if the main disconnect and
busbars are rated at 200 amps, and the PV system is capable of producing 40
amps, it is then possible to pull 240 amps off the busbars via feeders and
branch circuits, if the users of the system connect enough equipment simultaneously. Section 705.12(D)(2) requires that the "sum
of the ampere ratings of overcurrent devices in circuits supplying power to a
busbar or conductor shall not exceed 120 percent of the rating of the busbar or
conductor.” So, 240 amps are allowed onto busbars rated at 200 amps. But,
705.12(D)(7) requires that PV breakers be located at the opposite end of the
busbar from the utility feed. Figure 1 shows why. If the PV 40-amp breaker is
located adjacent to the utility feed, the sum of amperage on the busbars
immediately after that breaker can be 240 amps, too high for the metal of the
busbar. But, if the breaker is located at the opposite end, this cannot occur,
since power is fed from two different directions. As we will see, a similar scenario can exist
when tapping into feeders with a PV system.
Figure 1. PV load side connection at breaker complaint and non-compliant breaker locations
Tapping into Feeders
Figure 2 shows conductors from a PV inverter
connected to the system by tapping into feeder conductors coming off a breaker
in the service panel. The figure shows a service that has very few breaker
slots, only enough for feeders to a subpanel and several others for loads such
as AC and range. On such a panel, if all slots are taken, the installer cannot
add a breaker to connect the PV. The connection could be made with a breaker at
the subpanel (if all rules are followed), but routing conduit to a subpanel
inside the house is often difficult. A line side connection could be made at
this service panel, but this entails installation of an additional service
disconnect and could violate the terms of listing of the meter enclosure, which
was designed to handle only utility power. A separate subpanel could be
installed adjacent to the service, but this is expensive. Tapping directly into
the feeders is easy, but is it safe and compliant?
Figure 2. Load side PV tap overloaded feeders and busbars
Is This a Tap?
NEC 240.2 defines a tap conductor as "…a
conductor, other than a service conductor, that has overcurrent protection
ahead of its point of supply that exceeds the value permitted for similar
conductors that are protected as described elsewhere in 240.4.” In figure 2,
the overcurrent protection for the feeders exceeds the value permitted for the
PV conductors spliced onto the feeders, but one could argue that those feeders
are not the point of supply for the PV conductors, so that these conductors are
not "taps” at all. However, in the event of fault current between the splice
and inverter, the feeders will supply fault current to the spliced PV
conductors, and the only overcurrent protection to clear this fault is the
feeder OCPD. For this reason the PV conductors qualify as tap conductors, even
though in normal operation they will put current onto the feeders rather than
pull current off of them. If such an installation is allowed by the AHJ, the
tap rules of 240.21(B) must be followed.
Can a Tap Connect PV?
Section 705.12(D)(1) states that the connection
from an inverter must be made "at a
dedicated circuit breaker or fusible disconnecting means.” Figure 2 shows the
tap conductors originating from a 60-amp fused disconnect. Is the connection of
the PV system to the other system made at the tap splice itself, or is it made
at the 60-amp disconnect? Opinions seem to vary on this point. Some consider
that the tap conductors from the splice to the disconnect are part of the other
system, so that the two systems are connected at the disconnect. Others
consider that the tap conductors are part of the PV system, so that the two
systems are connected at the splice. Taking the latter position, the connection
is not compliant because it is not made at a breaker or fusible disconnect, but
rather at a splice. Taking the former, it is compliant since the connection is
at a fused disconnect. Since the code is silent on this issue, each AHJ must
decide this point for himself. The remainder of this article presumes that the
tap connection is judged compliant if it leads to a breaker or fusible
disconnect as in figure 2.
Overloading the Feeders
Figure 2 shows the PV system spliced into the
feeder conductors somewhere along their length. The feeders are protected by a
100-amp breaker. Let us say for sake of discussion that the feeders themselves
and the busbars on the subpanel are rated at 100 amps each, and that the PV
system is capable of putting 30 amps onto the feeders in sunlight. When few or
no loads are being pulled off the subpanel during daylight, the current from
the PV system will backfeed toward the utility. When more than 30 amps are
pulled from the subpanel in daylight, the 30 amps from the PV will go to the
subpanel and the utility will make up the difference. If the building users
connect enough equipment during daylight, they can conceivably pull a total of
130 amps through the subpanel before the 100-amp feeder breaker trips or the
30-amp PV breaker trips.
Let’s say the
users are pulling 130 amps and no breaker trips. The section of the feeders
from the 100-amp feeder breaker to the splice is carrying 100 amps, its maximum
rating. The PV tap conductors from the 30-amp disconnect to the splice are
carrying 30 amps, for which they are rated. But the section of feeders from the
PV splice to the subpanel busbars is carrying 130 amps. As well, the tops of
the busbars themselves, before any breakers take loads off the busbars, are
carrying 130 amps. In this case, both the feeders from the splice and the busbars
are well beyond their ratings and can overheat, distort, burn insulation, etc.,
with no breaker tripping to protect the circuit.
If the PV system were smaller and its breakers were
at 20 amps, the feeders from the splice and the busbar tops would carry 120
amps, which is 120 percent of their rating, and therefore compliant with
705.12(D)(2), the 120 percent rule. However, this installation still violates
the intent, if not exactly the wording, of 705.12(D)(7) which requires that the
connection in a panelboard be made at the opposite end of the busbars from the primary power source. But in this case, we
are dealing with a connection at feeders as well as at a panelboard. Since the
provision regards only a connection at a panelboard, it is debatable whether it
applies to feeders. But still the intent of the provision is clear — the
connections must be made in a way that avoids overloading any given section of
busbar or conductor. In both the 30-amp and 20-amp PV scenarios described
above, such serious overloading is possible because the tap does not connect at
the opposite end from the primary feed. It is added to the primary feed, so
that the sum of amperages enters the feeders mid-way, and the panel from only
one end, in these cases overloading both feeders and busbars.
Size Down the Feeder Breaker
Let us say
that the installer suggests sizing down the breaker for the feeders from 100
amps to 70 amps (in the 30-amp PV scenario). In this case, it will no longer be
possible to pull more than 100 amps through any section of conductor or busbar.
However, this assumes that 30 amps are always available from the PV system
which, of course, they are not when sunlight is not on the PV array panels. At
night the maximum that can be pulled through the subpanel is the 70 amps. If
load calculations for the building show that 70 amps is enough, this is a quick
fix for an otherwise non-compliant situation. If load calculations are over 70
amps, there is a risk of nuisance tripping at the feeder breaker; but the absence
of a working calculation should prevent the installation at all.
Oversized Feeders and Busbars
consider the situation if both the feeders and the subpanel busbars are
oversized to begin with. In figure 3, the feeders are rated for 140 amps and
the subpanel busbars are rated at 200 amps, but the feeder breaker is 100 amps
and the calculated load is below 100 amps. Now the installer taps into the
feeders with 30 amps, and the users connect enough equipment to pull 130 amps
through the subpanel during daylight. Current in the feeders is below their
rating, and the panel is well below its capacity; but this still seems to
violate the provision in 705.12(D)(7) which tells us to locate the PV
connection at the opposite end. Or does it?
The text reads,
"Unless the panelboard is rated not less than the sum of the ampere ratings of
all overcurrent devices supplying it, a connection in a panelboard shall be
positioned at the opposite (load) end from the input feeder location… .” In
this case, the sum of the ampere ratings of the breakers is less than the
ratings of the subpanel busbars or the feeder conductors, so no possibility of
overload exists. This code provision is written to cover scenarios where
busbars are not oversized to begin with, where the addition of another power
source presents a possible overload problem. But the provision allows for
situations where equipment is oversized to begin with, which avoids the
possibility of overload so long as the total amperage fed into the busbars is
below the capacity of the equipment. The same principle applies to the feeder
conductors. Section 705.12(D)(7) is in place to prevent overheated equipment.
It is not necessary to locate the PV connection at the opposite end of the
busbars in this scenario because connecting it ahead or anywhere else cannot
cause an overload.
Figure 3. Load side PV tap oversized feeders and subpanel busbars
Tapped Feeders in a Gutter
shows an installation where three subpanels are fed off of tap conductors in a
gutter. Two possible locations are shown for tapping a PV system onto the main
feeders along with the taps for the subpanels. The same principles apply here
as in the above scenarios. If the PV system tie in occurs upstream of the taps
for the subpanels (PV tap location 1), the section of feeder between the PV tie
in and the first subpanel tap splice can theoretically have an amperage running
through it that is equal to the sum of the main disconnect breaker and the
amperage supplied by the PV system. If this total amperage is greater than 120
percent of the rating of the feeder, 705.12(D)(2) is violated. If it is within
120 percent, it is still necessary to locate the tap at the opposite (load) end
of the feeder, just as you would do with locating a breaker on a busbar, to
comply with 705.12(D)(7). PV tap location 2 shown in the figure is located
where its amperage cannot be added to the amperage coming from the main
disconnect on any given length of the feeder, avoiding overloading that
section. But if the main feeder is oversized to begin with, locating the PV tap
upstream of the subpanel taps is compliant so long as no section of conductor
(or busbar) is overloaded.
Figure 4. Load side PV tap in a gutter with feeder taps
Most residential service load centers are not
designed to accept secondary sources of power such as PV systems. Connecting to
these load centers can be easily done with a backfed circuit breaker, within
certain parameters. But installers are
faced with connecting to a wide range of load center configurations, where
sometimes such a breaker cannot be installed. Sometimes a load-side tap is the
option of choice. Such a connection raises various code issues which inspectors
and installers must be aware of. The basic principles of installation laid down
in the code for use in connecting with circuit breakers also apply when
installing a load-side tap. Thorough understanding of the principles behind the
provisions is essential to ensure safe, effective installations of PV
connections with load-side taps.
John Wiles articles at New Mexico State University
can be found at:
Solar Ready Residential Service Panel
The photo shows a Siemens "solar
ready” service panel which is produced as a response to the need for easier
connections with PV systems.
This panel design constitutes a
line-side tap. A separate set of busbars, rated at 60 amps, is supplied for
connecting to an inverter with a set of breakers. That set of busbars is
connected directly to the load side of the meter socket before the main
disconnect, bypassing the main busbars altogether. This also bypasses all the difficulties
involved with load-side connections.
Since the line-side tap
connection is integral with the equipment and a part of its listing, it avoids
the problem of violating the listing of a panel by connecting a line-side tap
where the equipment is not approved for such use. But it will be a long time
before significant numbers of such panels are installed; and, meanwhile, the
majority of PV installations will be done on older service panels that were not
designed for the use.
With effective application of
existing code provisions, those panels can be safely utilized with PV while we
make the decades-long transition to equipment designed for the purpose. But 20
years from now, you’ll still see someone trying to do a line-side tap into a
rusty Zinsco 100-amp service at the meter socket, because there is no room for
more breakers and the owners would rather spend their cash on granite
countertops than a nice shiny new service panel.
Jeff Greef is a combination inspector with the City
of Cupertino in Silicon Valley, California.
Posted By Leslie Stoch,
Monday, September 16, 2013
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The Canadian Electrical Code Part I is a voluntary standard for adoption and enforcement by Canada’s provinces and territories, with provincial and territorial amendments. We rely on the CEC to provide safety standards for installation of electrical wiring and equipment. Its stated purpose is preventing electrical fire and shock hazards. But not all of its requirements are between its covers. Sometimes, we must get into other publications to obtain more complete information. This article reviews some examples.
Rule 12-012 provides, in great detail, the CEC requirements for installing high and low voltage underground conductors and their allowable ampacities (Table 53). At the end of this lengthy rule we find Rule 12-012(13) which advises us, that when an installation falls outside the scope of this rule, we must go to the underground standard, CAN/CSA-C22.3 No. 7. Reference to that standard brings its applicable parts into the CEC.
Rule 36-300 and Table 51 provide minimum grounding conductor requirements for substations over 750 volts for minimum copper wire sizes based on the available short-circuit current and fault current duration. A footnote to Table 51 indicates that wire sizes have been calculated using the IEEE Guide for Safety in AC Substation Grounding, ANSI/IEEE Standard No. 80. Table 52 provides maximum step and touch voltages in and around substations for several types of earth. You will note that a footnote to this table once again specifies that its values have been calculated using ANSI/IEEE Standard No. 80.
Rules 36-304 and 36-306 stipulate that maximum substation ground resistance for stations over 7500 volts must be calculated, based on available fault current levels and earth resistivities. Appendix B identifies the CEA Research Report 249-D-541 as the approved method of working out substation grounding electrode design. That document in turn references ANSI/IEEE Standard No. 80, which contains all of the formulae necessary for controlling step and touch voltages and conformance to Table 52.
Rule 32-200 requires that fire pump conductors be protected against fire exposure and to provide continued operation in compliance with the National Building Code of Canada. The rule refers us to Appendix B which elaborates on the rule — when called upon, fire and life safety systems must continue to operate for at least one hour. Checking Appendix B, we note it makes reference to NFPA Standard No. 80 as a further source of information for installation of fire pump wiring.
Rule 36-108 and Table 31 list minimum horizontal spacings between overhead conductors on pole lines for voltages up to 69 kV. A Table 31 footnote shows that the table does not cover voltages over 69 kV and pole spans greater than 50 m. For that information, we are referred to the CSA overhead lines standard CAN/CSA-C22.3 No. 1.
Rule 36-110 and Table 32provides vertical clearances for live parts up to 230 kV for indoor and outdoor substations for areas accessible only to pedestrians and areas accessible to vehicles. The vertical outdoor clearances are based on location — whether the substation is in a light or heavy snow area of the province or territory. Appendix B tells us that this information should be obtained from the Meteorological Service of Canada, Environment Canada, or the Atlas of Canada published by Natural Resources Canada.
Rule 18-000is the scope paragraph of Section 18 – Hazardous Locations. This rule refers to Appendix B which displays a long list of documents affecting the design of hazardous locations containing explosive gas atmospheres, combustible dusts or ignitable fibres. Appendix B shows 3 tables listing the applicable reference publications:
Table A – Documents generally applicable to all classes of hazardous locations.
Table B – Documents applicable specifically to Class I hazardous locations.
Table C – Documents Applicable specifically to Class II hazardous locations.
As you already know, the Canadian Electrical Code does not stand alone. As with previous articles, you should always check with the electrical inspection authority in each province or territory for a more precise interpretation of any of the above.
Read more by Leslie Stoch
Posted By Joseph Wages, Jr.,
Monday, September 16, 2013
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Fountains and reflection pools have been around for generations and make powerful statements and reminders of events that occurred at these locations. Beautifully built and constructed throughout the world, these locations are often works of art.
Photo 1. McKinney, Texas
On April 19, 1995, at 9:03 a.m., a tremendous explosion destroyed the Alfred P. Murrah Federal Building in Oklahoma City and 168 people lost their lives; but as a country, we lost much more. No longer could we take for granted that something like this could never happen again. As a people, we would always wonder when it would again. We looked at our children differently and gave them extra hugs. Things could never be the same again.
Photo 2. Oklahoma City Memorial
This happened in Middle America or what some consider Flyover country, and would leave its mark on the country as one of the worst domestic acts of terrorism to date. Many years later in 2001, the events known as "9/11” and the collapse of the Twin Towers would change this image and result in war.
Today, a reflection pool is part of the Oklahoma City Memorial, a solemn reminder of those events that allows the visitor to see his or her reflection as "someone changed by the events of that day.”
This destructive act took place roughly two hours from my home. Being a father, the loss of children weighed heavily on my heart. As a visitor to the site, I recall, my emotions were all over the place. I had gone as part of a group of men attending a Promise Keepers Rally held in the downtown area. It seemed that thousands stopped at the fountain to reflect on the events, to honor the victims, and to remember that which is important in life. On that day, for me, life took on new meaning in a personal way.
As you can imagine, the National Electrical Codehas requirements that govern electrical installations at these locations. Certain tragedies are, unfortunately, unavoidable due to the ill will of others. We can certainly do our best, however, to minimize or prevent senseless disasters from occurring by enacting strong Code adherence and educating as to its importance.
Photo 3. Fountain, Hot Springs, Arkansas. Millions of people have visited the waters found in Hot Springs National Park. Throughout Hot Springs there are numerous fountains and bath houses. Some people claim the waters from the fountains have therapeutic properties; and many of them use water bottles to "capture” this water for drinking purposes. But be careful at the fountains; you will find out quickly that the water is hot, and on a cold day, one can view the steam as it rises and quickly disappears.
Article 680 Swimming Pools, Fountains, and Similar Installations
I remember seeing my first fountain as a small child. This fountain was located inside the AQ Chicken House in Springdale, Arkansas. My mom would take us there when we would visit her brothers and sisters, and I would always ask for pennies to throw into the water. As I look back, this was an innocent time where wishes could be made with an expectation that they might happen. I can say that I never got any taller or got a chance at the NBA; but the fountain got a little richer from all those pennies from wish-making kids! This article deals with the construction and installation of electrical wiring at these locations.
Article 680 deals with these and other similar areas, such as the locations listed below:
- Swimming, wading, therapeutic and decorative pools
- Hot Tubs
- Hydromassage Bathtubs
We also need to keep in mind that the term body of water, used throughout Part I, applies only to bodies of water detailed in the scope, unless it has been otherwise amended. In this article we are going to look specifically at fountains and reflection pools. To do so, we need to start at the definitions.
Definitions are important to any project. The definitions we are interested in reside in 680.2. It is interesting to see that a reflection pool is located in the definition of a fountain.
Fountain. Fountains, ornamental pools, display pools, and reflection pools. The definition does not include drinking fountains.
Pool. Manufactured or field-constructed equipment designed to contain water on a permanent or semi-permanent basis and used for swimming, wading, immersion, or therapeutic purposes. (2011 NEC)
The term fountainapplies also to: ornamental pools, display pools, and reflection pools. Think about your Koi Pond tucked in the corner of your back yard. Have you ever considered it an ornamental pool? What about a display pool? What exactly is displayed at these pools? Reflection pools are familiar to many people; not only the reflection pool in Oklahoma City but also the reflection pool at the site of the former Twin Towers in New York City.
Interestingly enough, the code-making panelshad to take action on drinking fountains in the 1999 NEC. Language was placed into the definition specifically stating that drinking fountains were not included in the definition of fountains. It also made it clear that Article 680 did not apply to drinking fountains. This leads one to speculate that maybe an AHJ could have been trying to enforce the requirements found in Article 680 towards the drinking fountain.
Photo 4. Fountain luminaire with cord. Overheating protection of the electrical equipment is necessary for electrical equipment that depends on submersion for safe operation. A low-water cut-off or other approved means shall be provided when the equipment is no longer submerged.
Article 680 Part V, Fountains
Part five is where we zoom in on the specific requirements for fountains. The provisions of Part I and Part V of the article shall apply to all permanently installed fountains as defined in 680.2. As one might expect, luminaires, submersible pumps, and other submersible equipment shall be protected by a ground-fault circuit interrupter, unless listed for operation at low voltage contact limit or less and supplied by a transformer or power supply that complies with 680.23(A)(2).
So, what is meant by the low voltage contact limitas discussed above? This definition was new for the 2011 NEC. Let’s review this term.
Low Voltage Contact Limit
A voltage not exceeding the following values:
(1) 15 volts (RMS) for sinusoidal ac
(2) 21.2 volts peak for non-sinusoidal ac
(3) 30 volts for continuous dc
(4) 12.4 volts peak for dc that is interrupted at a rate of 10 to 200 Hz
[Excerpt from 2011 NEC,680.2]
"The low voltage contact limit described in this definition is based on the wet contact limits specified in Tables 11(A) and 11(B) in Chapter 9. In prior editions of the Code, the use of isolated winding type transformers that provided a sinusoidal ac voltage not exceeding 15 volts was used as the low voltage operational threshold for underwater luminaires. Although the 15-volt limit in Article 680 was based on a transformer-type power supply, it applied to all low- voltage systems. Any luminaire operating at more than 15 volts was required to be protected by a ground-fault circuit interrupter.
"In addition to sinusoidal alternating current, this definition also identifies the maximum acceptable safe levels for other voltage systems. Depending on the system, this maximum level is either higher or lower than that considered safe for sinusoidal ac voltage. New technologies for underwater lighting that integrate power supplies other than the traditional isolated winding type transformer have been developed, and this definition and associated requirements in Article 680 ensure that those new power supplies can be safely integrated into the swimming pool environment.” [Excerpt from 2011 NEC Handbook]
Photo 5. Sign in fountain, Fort Worth, Texas
Luminaires, Submersible Pumps and Other Submersible Equipment
The operating voltage for luminaires and submersible pumps and other submersible equipment is different. The operating voltage for supply circuits for luminaires shall not exceed 150 volts between conductors. The operating voltage for submersible pumps and other submersible equipment shall not exceed 300 volts or less between conductors.
Luminaires shall be installed in specific locations within these environments. Unless listed for above-water locations, the top of the lens shall be below the normal water level of the fountain. In the event that the lens is facing upward, it is to be adequately guarded to prevent contact by any person, or it is to be listed for use without a guard.
Nice to Know Info
Maximum Water Level. The highest level that water can reach before it spills out.
Note: Normal water level is different in each and every situation. As you might think, to define such a level would be impractical as each fountain or reflecting pool will be different. Therefore, it is recommended that you discuss the normal water level with the designer of the fountain before the project begins.
There is nothing that requires the installation of a luminaire in a pool of water; it is done by choice. Many luminaires are installed for aesthetic purposes to add to the enjoyment and tranquil feeling one might experience at the locations. Most generally, luminaires accentuate features found at that location.
The equipment located in fountains shall contain provisions for threaded conduit entries or shall be provided with a suitable flexible cord as required by 680.51(E). A maximum limit of 3.0 m (10 ft) has been mandated for the exposed cord within the fountain. Any cord located on the perimeter of the fountain shall be enclosed in an approved wiring method. An approved corrosive-resistant metal shall be used when metal parts are in contact with water. An example of a metal part that meets this requirement is brass.
Photo 6. Fountain in downtown Kansas City, Missouri
Equipment servicing is an important consideration when installing pool equipment. All equipment shall be removable from the fountain. This will allow for relamping of luminaires and for normal maintenance of equipment. Luminaires cannot be permanently embedded into the fountain structure so that water has to be removed or the fountain has to be drained in order to service the luminaires and equipment. All equipment that is to be part of a fountain shall be securely fastened in place or shall be inherently stable.
Nice to Know Info
What does "inherently stable” mean?
Inherent stability is often found throughout the aviation industry. It is the tendency of an aircraft to return to straight and level flight, when the controls are released by the pilot. Most aircraft are designed with this in mind and are said to be "inherently stable.” I guess that when applied to pool equipment, the equipment should return to its previous location and remain stable. Might there be an aviation guru involved with the NFPA process that got this term used here as well?
Receptacle Outlets Adjacent to Fountains
Fountains contain water. Water and electricity typically do not play well together. When we consider receptacles near fountains, we must keep this in mind. Ground-fault protection of these devices is necessary to ensure the safety of the user of the fountain. Any receptacle located within 6.0 m (20 ft) of the edge of the fountain shall be provided with GFCI-protection. This information can be found at 680.58.
Always remember to review the requirements for placement of equipment and other items associated with fountains. Code language dictates that the measurement for this equipment shall be made from inside the pool wall. Other code language from Article 680 for other situations will direct the installer to take the measurement from the outside of the pool wall. This requirment is located in 680.34. A slight oversight in reading and understanding these different requirements could be crucial to your receiving the final inspection results that make you happy.
Some fountains will be designed with signs in mind. Signs can take on many forms and fashions. The NEC deals with electric signs so not all signage will be affected by this language. Electric signs installed within a fountain or within 3.0 m (10 ft) of the fountain’s edge will be discussed next. Section 680.57(C) directs that "a fixed or stationary electric sign installed within a fountain shall be not less than 1.5 m (5 ft) inside the fountain measured from the outside edges of the fountain.”
In the event the sign is portable, we have two restrictions: (1) it shall not be placed within a pool or a fountain; and (2) it cannot be placed within 1.5 m (5 ft), measured horizontally, from the inside wall of a fountain.
A sign shall be grounded and bonded in accordance with 600.7. A disconnecting means conforming with both 600.6 and 680.12 shall be provided for a sign used with fountains.
Boxes and Enclosures
Boxes and enclosures are very important in a wet or damp location. These items will need to conform to 680.24 when used at a fountain. Each will need to be provided with threaded conduit entries or compressed glands and seals for cord entry. If the box or enclosure is to be submersible, it shall be constructed of copper, brass, or another approved corrosion-resistant material.
Section 680.52(B)(2)(a) requires a potting compound to prevent the entry of moisture for an underwater enclosure. The box or enclosure shall be firmly attached, per 680.52(B)(2)(b), to the fountain surface. If the box or enclosure is supported solely by conduits, the conduit shall be of copper, brass, stainless steel or another type of corrosion-resistant metal. Support shall be in accordance with 314.23(E) and (F).
Bonding and Grounding of Fountain
Do not take for granted the importance of grounding and bonding, which cannot be stressed enough in the installation process for the fountain. Bonding requirements are located at 680.53. The Informational Note further directs you to 250.122 for the sizing of these conductors that are attached from the metal piping systems to the equipment grounding conductor of the branch circuit.
Some equipment must be grounded. In 680.54, we find guidance that helps with this process. All electrical equipment — other than listed low-voltage luminaires not requiring grounding — located within the fountain or within 1.5 m (5 ft) of the inside wall of the fountain must be grounded. This also includes electrical equipment associated with the circulating system of the fountain, regardless of its proximity to the fountain.
Methods of grounding are discussed at 680.55(A). There are six code references that have applicable provisions for the fountain or reflection pool. In the event you have equipment supplied by a flexible cord, 680.55(B) needs to be consulted. All exposed non–current-carrying metal parts of electrical equipment that is supplied by a flexible cord shall be grounded by an insulated copper equipment grounding conductor that is an integral part of this cord. It shall be connected to an equipment grounding terminal located at the supply junction box, transformer enclosure, power supply enclosure, or other enclosure.
Cord- and Plug-Connected Equipment
We can’t escape cord- and plug-equipment. For guidance on installation practices, turn to 680.56(A) through (D). Maintenance of electrical equipment dictates that the power supply cords allow for this type of flexibility. Hence, all power supply cords shall be protected by ground-fault circuit interrupters.
There are also requirements that dictate the choice for cord types when used in fountains and reflection pools. If immersed in or exposed to water, a flexible cord shall be of the extra-hard usage type. This is typically designated in Table 400.4. The flexible cord shall also be a listed type with a "W” suffix.
A suitable potting compound is required for the end of the flexible cord jacket and for the flexible cord conductor that are intended to terminate within the equipment. This will prevent the entry of water into the equipment through the cord or its conductors. To prevent deteriorating effects from the water that may enter into the equipment, the ground connection shall be treated as well.
All flexible cord terminations shall be permanent, except for devices that need to be removed for maintenance, repair, or storage. This could include grounding-type attachment plugs and receptacles. Some of this equipment will be removed for storage and protection from the elements. Fountains are located at inside and outside locations throughout the world. In the event of freezing conditions, some of the equipment could be ruined. Removal of these items is essential to protect the equipment from these weather-related effects.
Photo 7. Spiritual Fountain, McKinney, Texas
I did not install the electrical equipment or inspect the fountain where I currently live. I am taking for granted that each person involved with this project has installed it as prescribed by the rules found within the National Electric Code. I think that if we all remembered how it could affect the end user, we would always have code-compliant projects. As stated earlier, water and electricity do not play well together. Enter a human life and things could go horribly wrong. It does not take a misguided individual blowing up a building to affect our daily lives; an unintentional mistake or oversight can have the same effects. Code requirements are important. Electrical installers are important. Electrical inspectors are important. Your loved ones are important to you! Who knows when they might visit or get into that pool!
Read more by Joseph Wages, Jr.
Posted By Steve Douglas,
Monday, September 16, 2013
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What are the criteria for connecting more than one motor on a single branch circuit overcurrent device?
To start to answer this question we need to re-visit the Canadian Electrical Code Part I (CE Code) definition of a branch circuit to recognize that a motor branch circuit is the circuit between the final overcurrent device and the motor including the conductor and the motor controller. In accordance with the CE Code the motor branch circuit conductors, controllers, and motors require short circuit protection in the form of an overcurrent device and motor requires overload protection.
Let’s start with the overload protection which is unique to a motor only.
The overload protection for the motor is designed to protect the motor in the event the motor is overloaded. The overload protection can be in the form of inherent overheating protection such as thermal protection (thermally protected or tp) or impedance protection (impedance protected or zp) as detailed in CSA Standard C22.2 No 77 Motors with Inherent Overheating Protection. A motor recognised as a motor with inherent overheating protection must be marked on the motor. (See photos 1 and 2).
Photo 1. A motor marked with inherent overheating protection
Photo 2. A motor that does not have inherent overheating protection
Other than the limited motors less than 1HP identified in CE Code Rule 28-308, motors not provided with inherent overheating protection will require remote overload protection. The setting of this overload protection is detailed in CE Code Rule 28-306. Motors with a service factor 1.15 and greater require the overload protection set at 125% of the motor full load ampacity and 115% for motors with a service factor less than 1.15. (See photo 3).
Photo 3. A motor nameplate where we can see the service factor (SF) of 1.15.
Remote overload protection can be provided by time delay fusing, overload relays, or other overload devices certified to CSA Standard C22.2 No 14 Industrial Control Equipment. (See photo 4).
Photo 4. Motor overload relay for a motor that does not have inherent overheating protection
With the overload dealt with, we can now focus on the short circuit protection requirements. The traditional method to provide short circuit protection is by the installation of overcurrent devices such as fuses or circuit breakers with an ampacity rating based on CE Code Table 29. As an example, the short circuit protection (overcurrent protection) required for a synchronous motor is limited to 175% of the motor full load ampacity for time delay fuses, 300% for non-time delay fuses and 250% for circuit breakers. Such limitations are intended to allow the motor to start without operating the overcurrent device during normal operation of the motor.
In the uncommon event these ratings of protection do not allow the motor to start because the motor inrush current is too high, CE Code Rule 28-200(d) allows the overcurrent protection to be further increased to 225% of the motor full load ampacity for time delay fuses, and (400% for motor up to 100 FLA and 300% for greater than 100 FLA) for circuit breakers.
Another method to provide short circuit protection is by using self-protected combination motor controllers also known as Type E or Type F combination motor controllers. CSA Standard C22.2 No 14 defines these controllers as:
A combination motor controller having non-replaceable or integral discriminating overload and short circuit current sensors, and provided with one or more sets of contacts where the contacts cannot be isolated for separate testing, shall be considered a Type E. (See photos 5A and 5B).
Photo 5A. Two Type E self-protected combination motor controllers. Photo 5B. The nameplate for one of the Type E self-protected combination motor controllers shown in Photo 5A. Note the accessories identified on the nameplate marking that must be installed before the controller can be accepted as a Type E self-protected combination motor controller.
A Type F combination motor controller is comprised of a magnetic or solid state motor controller coupled with a Type E controller. (See photos 6A and 6B)
Photo 6A. A Type F combination motor controller. Photo 6B. The nameplate for Type F combination motor controllers is shown in Photo 6A. Note the accessories identified on the nameplate marking that must be installed before the controller can be accepted as a Type F combination motor controller.
Type E and Type F self-protected combination motor controllers provide a disconnection means, short-circuit protective device, motor controller, and overload protection.
Another method to install multiple motors on a single branch circuit is with a controller marked suitable for motor group installation in conjunction with a main branch circuit overcurrent device (fuse of circuit breaker). (See photo 7).
Photo 7. A motor controller marked suitable for motor group installation
Precautions must be considered when grouping motors on a single branch circuit. The first precaution to consider is the markings on the controller for such group installations. CSA Standard C22.2 No 14 requires the maximum overcurrent protection to be marked on the controller. (See photo 8).
Photo 8. The maximum overcurrent protection that can be installed ahead of the group installation controller.
The second precaution to consider is the requirements of CE Code Rule 28-206. This rule directs code users to Rule 28-204 to limit the maximum overcurrent protection that can be installed ahead of the group installation controller.
For a feeder supplying motor branch circuits only, the ratings or settings of the feeder overcurrent device shall not exceed the calculated value of the overcurrent device permitted by Rule 28-200 for the motor that is permitted the highest rated overcurrent devices of any motor supplied by the feeder, plus the sum of the full load current ratings of all other motors that will be in operation at the same time.
As an example let’s look at a motor group installation consisting of five synchronous motors with full load ampacities (FLA) of 21, 2, 4, 7, 7, 7, and 16 A, and a main breaker installed ahead of the controllers marked suitable for group installation. (See table 1).
CE Code Rule 28-206 limits the circuit breaker ahead of the group installation to a maximum of 93 A 21x2.5=52.5 = 50 Amp breaker + (2+4+7+7+7+16). Note: the marking on the controller for Motor 2 limits the main circuit breaker to 80 A. As a result, this example for is not code-compliant. One option is to replace the Motor 2 controller with a group installation controller marked for a maximum 125 A circuit breaker and ensure the main breaker is not larger than 125 A.
The third precaution is the size of the circuit conductors including the tap conductors. The tap conductors are the conductors installed between the group installation controllers and the motors. CE Code Rule 28-106(3) limits the size of the tap conductor to not less than 1/3 that of the larger branch circuit conductor for the group of motors.
The minimum allowed ampacity of the branch circuit conductors for the group of motors in this example is 69.25 A, 21x1.25 + (2+4+7+7+7+16). From the 75⁰C column of CE Code Table 2, a 4 AWG copper conductor with the ampacity of 85 A has been selected. The following table shows the tap conductor sizes and percentages of the larger conductor for our example. (See table 2).
As you see, the Motors 2 to 6 have 14 AWG copper conductors with an allowable ampacity of 20 A that is less than 1/3 of the larger 4 AWG copper conductor allowable ampacity of 85 A. This can be made code-compliant by installing 12 conductor in place of the 14 AWG copper conductors, or separating the largest motor from the group reducing the main circuit breaker and larger conductor size. The following table shows the revised group without Motor 1. This group would now have a maximum main circuit breaker of 70 A, 16x2.5 = 40 Amp breaker + (2+4+7+7+7) and a minimum conductor allowable ampacity of 47 A, 16x1.25 + (2+4+7+7+7). Resulting in a 8 AWG copper conductor as the larger conductor supplying the group installation controllers. (See table 3 ) .
The final precaution to consider is the length of the tap conductors. CE Code Rule 28-106(3) limits the length of the tap conductors to a maximum of 7.5 m. The following table shows our revised example detailing the tap conductor lengths proposed. (See table 4).
As you can see the length of the tap conductor for Motor 4 is not code-compliant. If the conductor cannot be rerouted to limit the length of the tap conductor to 7.5m, individual overcurrent would need to be installed ahead of the tap for Motor 4.
The limitations when grouping motors on a single overcurrent device include the method of motor overload protection, short circuit protection for the motor branch circuit conductors, controllers and motors, size of the tap conductors, and the length of the tap conductors. The overload protection can be in the form of integral protection for the motor or remote overload protection as part of the control equipment. The maximum overcurrent device used to provide the short circuit protection for the motor branch circuit conductors, controllers, and motors must not exceed the limitations of Rule 28-206 and cannot exceed the maximum rating permitted by the rating marked on the group installation motor controller. The motor tap conductors must have an allowable ampacity not less than 125% of the motor full load ampacity. The motor tap conductor allowable ampacity must also be greater than 1/3 that of the larger conductor installed ahead of the group installation motor controller, and the maximum length of the motor tap conductor cannot exceed 7.5m.
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Posted By Jesse Abercrombie,
Monday, September 16, 2013
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If you own a business, you may well follow a "do it now” philosophy; which is, of course, necessary to keep things running smoothly. Still, you also need to think about tomorrow, which meansyou’ll want to take action on your own retirement and business succession plans.
Fortunately,you’ve got some attractive options in these areas. For example, you could choose a retirement plan that offers at least two key advantages: potential tax-deferred earnings and a wide array of investment options. Plus, some retirement plans allow you to make tax-deductible contributions.
In selecting a retirement plan,you’ll need to consider several factors, including the size of your business and the number of employees. If your business has no full-time employees other than yourself and your spouse, you may consider a Simplified Employee Pension (SEP) plan or an owner-only 401(k), sometimes known as an individual or solo 401(k). Or, if your goal is to contribute as much as possible, you may want to consider an owner-only defined benefit plan.
If you have employees, you might want to investigate a SIMPLE IRA or even a 401(k) plan. Your financial advisor, working with plan design professionals and your tax advisor can help you analyze the options and choose the plan that fits with your combined personal and business goals.
Now, let’s turn to business succession plans. Ultimately, your choice of a succession plan strategy will depend on many factors, such as the value of your business, your need for the proceeds from the sale of the business for your retirement, your successor, and how well your business can continue without you. If your goal is to keep the business within the family,you’ll need to consider how much control you wish to retain (and for how long), whether you wish to gift or sell, how you balance your estate among your heirs, and who can reasonably succeed you in running the business.
Many succession planning techniques are available, including an outright sale to a third party, a sale to your employees or management (at once or over time), or the transfer of your business within your family through sales or gifts during your life, at your death or any combination thereof.
Many succession plans include a buy-sell agreement. Upon your death, such an agreement could allow a business partner or a key employee to buy the business from your surviving spouse or whoever inherits your business interests. To provide the funds needed for the partner or employee (or even one of your children) to purchase the business, an insurance policy could be purchased.
Your estate plan — including your will and any living trust — should address what happens with the business, in case you still own part or all of it at your death. The best-laid succession plans may go awry if the unexpected occurs.
All these business succession options can be complex, so before choosing any of them, you will need to consult with your legal and financial advisors.
Whether it’s selecting a retirement plan or a succession strategy,you’ll want to take your time and make the choices that are appropriate for your individual situation.
You work extremely hard to run your business, so do whatever it takes to help maximize your benefits from it.
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Posted By David Clements,
Monday, September 16, 2013
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It seems that every time we turn the television on or check our mobile device we hear about a disaster: floods, tornadoes, wild fires and explosions. I recall, in 1992 while living in Nova Scotia, how an explosion at the Westray coal mine located in a small community of Plymouth, Nova Scotia, claimed the lives of 26 miners. The bodies of those miners were never recovered and remain deep within the mine. Justice Peter Richard in his report on the explosion and fire said, "The Westray story is a complex mosaic of actions, omissions, mistakes, incompetence, apathy, cynicism, stupidity and neglect.”
His report also cited safety abuses, among them, inadequate ventilation design and maintenance to keep methane and coal dust at safe levels; methane detectors that were disconnected because of frequent alarms; procedures to "stonedust”1 coal to render it non-explosive, which were done sporadically, usually before inspections; and an "appalling lack of safety training and indoctrination” of miners.
On April 17, 2013, an ammonium nitrate explosion occurred at the West Fertilizer Company storage and distribution facility in the town of West, Texas, killing 15, injuring more than 160, and causing property damage in the millions. The authorities have yet to determine the cause.
With any major disaster, some are preventable and others are not. An investigation is conducted into the cause, reports are filed, and recommendations are made. In many cases, it is determined that either there was a lack of regulations, standards or compliance. What lessons are learned?
In June of this year I attended the National Fire Protection Association (NFPA) Annual Expo and Conference held in Chicago, Illinois, and the Canadian Standards Association (CSA) Annual Conference held in Calgary, Alberta. At these meetings, experts in their field voted on changes that will be incorporated in the next edition of the National Electrical Code (NEC) and in Canadian Electrical Code, Part 1 (CEC).
I witnessed the passion and commitment individuals representing their organizations had towards developing new requirements ensuring products and installations are safe from fire and shock hazards. The development of these standards is based on a balanced matrix of industry professionals and through a consensus process. IAEI technical committee members play a major role in this consensus process as they bring forth the inspectors’ perspective and knowledge.
These groups and individuals understand the value of standards. However, there are still cynics out there who are not part of the code development process that believe we are overregulated, and who feel that changes are made in the codes only to benefit manufacturers and that costs outweigh the safety benefits. We saw this when GFCIs were first introduced, and we are now seeing the same argument with AFCIs.
So do these cynics understand the value of standards — that standards help streamline process, and provide rules, guidelines and instructions for producing predetermined results? Without electrical standards would you feel safe in your home?
We have a responsibility and due diligence to ensure standards are developed and revised when problems, gaps and new products are identified. However, one cannot rely on standards alone to ensure that a product or installation is completely safe. It requires a systematic approach which includes four components: (1) applying current electrical standards (NEC) and (CEC); (2) installations performed by qualified installers; (3) third party certification of products; and (4) enforcement by qualified electrical inspectors.
So never underestimate the importance and tangible benefits of implementing the systematic approach.
William Blake, English poet, said, "What is now proven was once only imagined.” Hindsight is a wonderful thing but foresight is better, especially when it comes to saving life, or some pain!
1Stone dust (mining engineering) Inert dust spread on roadways in coal mines as a defense against the danger of coal-dust explosions; effective because the stone dust absorbs heat. McGraw-Hill Science & Technology Dictionary
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