Posted By Steve Foran,
Monday, July 02, 2012
Updated: Monday, September 10, 2012
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Here is a simple idea to enhance your capacity for leadership using gratitude. Gratitude is often misinterpreted as a sign of weakness — especially in business. For instance, the majority of my clients at some point tell me that they are nervous about hiring me because they were not sure how their people would respond to the idea of gratitude, but it does not take long for them to realize that gratitude can seriously improve their ability to lead others and to achieve results.
I remember one of my first projects as a young engineer. I was in charge and the crew assigned to the project included two very experienced technicians. They knew much more about the challenge we faced than I did. In fact, if it were not for these two men, we would not have successfully completed the project. Even though I relied on their experience, there were several times when I did not take their advice because it was wrong; it went against the laws of physical science. I did not tell them they were wrong. On the contrary, I was quite diplomatic but at these times they became very difficult to work with.
In getting to know them during the job, I discovered why they became so defensive and challenging. They related a story of a previous boss who called them into the office one day. One of them described what happened, "He had a bucket of water on his table. He told me to put both of my hands into the bucket and then take them out. He then asked me, ‘What difference do you see?’ I said, ‘Nothing.’ Then he looked at us both and said, ‘Exactly. And that is the difference I will see in this shop if you leave.’”
These two were not the easiest people to work with but they deserved better than being treated as a pair of hands whose sole purpose is to get a job done. They were not appreciated. They knew this, which was apparent by how they acted at work. Nobody wants to be treated disrespectfully and although it is not that people set out to intentionally use others, it happens.
As a leader, you get to choose how you treat others. There is an idea that I call the Grateful Leader that can improve how you lead. This does not replace the leadership philosophies that you already successfully use. Instead, incorporate this idea into your leadership style. Quite simply, as a Grateful Leader, you see your role as one that has been entrusted to you by "the many” who went before you. And in gratitude, you want to pass on your role of leadership in a condition better than it was given to you.
Grateful Leaders achieve results and treat people with dignity and respect. They differentiate between their responsibility as a leader and the people they lead in a very significant, but subtle way.
Possess the responsibility of leadership
As a Grateful Leader, you are responsible not out of duty or obligation, but rather true appreciation and recognition that your role is a gift entrusted to you. Grateful Leaders do not blame others but own this responsibility and use it wisely to achieve their desired results. They care for their responsibility like something sacred, knowing that their leadership engenders greater meaning in the world.
Be in relation to those you lead
Grateful Leaders do not possess the teams they lead, instead they are a part of the team. They see their team as a group of individuals worthy of dignity and respect. When the Grateful Leader says, "My team,” he or she does not mean it as when you say, "My car.” Rather, they mean it as when you say, "My family.” You own your car, you do not own your family; you are in relation to your family. This has a huge impact on how the leader treats others. The Grateful Leader acknowledges that every person, even the difficult to deal with person, has intrinsic value. They do not treat people as objects or simply as a means for the leader to achieve a goal.
No rocket science here, just common sense. Unfortunately this common sense can easily be forgotten under the pressure to produce or when distracted by a deadline.
Whether it is written on paper or in the minds of those you lead, those who look to you for leadership are writing your leadership story. What legacy do you want leave?
Read more by Steve Foran
Posted By Ark Tsisserev,
Sunday, July 01, 2012
Updated: Friday, September 07, 2012
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No, really — who is to say? Where is such entity defined or described? The answer could be found in two following documents:
- In the CSA standard Z32, which is actually called Electrical safety and essential electrical systems in health care facilities; and
- In Section 24 of the Canadian Electrical Code which covers installation of electrical equipment in patient care areas.
Photo 1. An essential electrical system consists of loads and branches listed in Table 7, and such loads represent a combination of the electrical equipment comprising "life safety systems” defined and described in Section 46, CE Code, and electrical equipment essential for care of the patients for effective operations of the health care facility (i.e., electrical equipment that in addition to life safety systems is also supplied by vital, delayed-vital or conditional branches).
CSA standard Z32 offers the following definition of essential electrical system: "Essential electrical system — an electrical system that has the capability of restoring and sustaining a supply of electrical energy to specified loads if the normal supply of energy is lost.”
Clause 6 of Z32 is dedicated to all aspects of an essential electrical system including normal and emergency power supply arrangements and redundancy of power sources, requirements for transfer of power and for the maintenance and repair of transfer switches. Table 7 of Z32 lists types of the essential electrical system loads and branches and subdivides these branches for the purpose of life/public safety and patient care as vital, delayed vital and conditional branches.
Section 24 of the CE Code also offers almost identical definition of an essential electrical system and provides a clear description of the circuits comprising the essential electrical system and the requirements for wiring to these circuits.
However, let’s find out what these two documents are about. Scope of CSA standard Z32 states the following:
This Standard deals with the following subjects:
(a) electrical safety associated with health care provision; and
(b) essential electrical systems for health care facilities.
Note: See Clause 3 for the definition of "health care facility”.
It is interesting to note that the reference to the definition of health care facility appears immediately at the outset of the scope of this standard, as a misapplication of this document is a very common occurrence. Clause 18.104.22.168 of the scope advises the users of this standard that the standard is not intended to be applied to veterinary facilities.
22.214.171.124 This Standard is not intended to apply to veterinary facilities, although its electrical safety principles could prove useful in the design, construction, and operation of such facilities.
The scope of this standard also describes the relationship with the applicable provisions of the Canadian Electrical Code as follows:
1.1.3 Provisions of this Standard are supplementary to the installation requirements specified in Sections 24 and 52 of the Canadian Electrical Code, Part I.
So far, so good. But how far is the scope of this standard intended to apply in a typical hospital? Would it cover such areas as a parking garage, offices, cafeterias, etc.?
The answer is provided in Clause 1.2.1 as follows:
1.2.1 This Standard applies to (a) patient care areas of Class A, Class B, and Class C health care facilities; and (b) areas outside health care facilities that are intended for patient diagnosis, treatment, or care involving intentional electrical contact of any kind between patients and medical electrical equipment.
Let’s take a look at the definition of health care facility and at the types of such facilities under the scope of this standard. This could help us in understanding whether a typical chiropractor’s office, dental hygiene office or a massage/physiotherapy office in a strip mall would fall under the scope of this standard.
Z32 offers the following definitions of health care facility and of specific classes of a health care facility:
Health care facility (HCF) — a set of physical infrastructure elements supporting the delivery of specific health-related services.
HCF, Class A — a facility, designated as a hospital by the government of Canada or the government of a Canadian province or territory, where patients are accommodated on the basis of medical need and are provided with continuing medical care and supporting diagnostic and therapeutic services. Note: Class A facilities include acute and complex care.
HCF, Class B — a facility whose residents cannot function independently because of a physical or mental disability and are accommodated because they require daily care by health care professionals.
Note: Class B facilities provide, e.g., extended, multi-level, hospice, psychiatric, or intermediate care. The definition includes rehabilitation facilities.
HCF, Class C — a facility where ambulatory patients are accommodated on the basis of medical need and are provided with supportive, diagnostic, and treatment services.
Note: Class C facilities include, e.g., outpatient and surgical clinics, dental offices, doctors’ clinics, private residences, and group homes.
These definitions clearly explain that both a huge hospital with the most comprehensive surgical, diagnostic and treatment infrastructure and a private residence where only a basic supportive medical care could be provided, would fall under the scope of this standard. This means that essential electrical systems (with all subsequent requirements for its installation and operation) would have to be arranged not only for the large hospital with dozens of operating rooms and variety of intensive care units, but also for a basic doctor’s office or even a group home.
The latter proposition sounds quite intimidating, as there are not too many (may be none) doctors’ offices or physiotherapy offices located in a typical retail mall or a typical office building that would be provided with all electrical infrastructure that comprise loads of a defined essential electrical system.
Perhaps, now a couple of other definitions of Z32 would be handy, as these definitions could help the readers to understand the extent of application of the essential electrical system described in Clause 6 of Z32 and in Rule 24-302 of the CE Code. These definitions deal with a very unique entity which is referenced by Clause 6 of Z32 and by Rule 24-302 in respect to essential electrical system. This entity is "administrator” or "administration” of a health care facility.
Administrator — the person responsible for operating the health care facility (or his or her designee).
Note: The term "administrator” is used in this Standard to denote the authority representing the health care facility and charged with responsibilities specified in this Standard. The administrator may (and usually does) delegate these responsibilities to appropriately qualified individuals.
Health care facility administration — the unit responsible, under the authority of a health care facility governing board, for planning, organizing, directing, and controlling the health care facility in accordance with the bylaws of the health care facility, the policies of the health care facility governing board, and government statutes, regulations, and directives.
So, why these two definitions are so critical for the purpose of the extent of essential electrical system for a particular class of a health care facility (or even for the applicability of essential electrical system for the health care facility)? The answer could be found in the scope of Clause 6 of Z32 as follows:
6.1.1 The requirements of Clause 6 shall apply to electrical systems that are considered essential for life and fire safety as specified in Article 126.96.36.199 of the National Building Code of Canada, for effective and safe patient care, and for the effective operation of the HCF during an interruption of the normal electrical supply for any reason.
6.1.2 The requirements of Clause 6 shall also apply to those portions of an HCF in which the interruption of the normal supply of power to the essential electrical system loads described in Table 7 would produce unacceptable risk to the effective and safe care of patients.
(1) Essential electrical systems should not be automatically deemed necessary for areas where the risk to patient safety is not dependent on the availability of the electrical supply. It is intended by Clause 6 that the administrator of an HCF may determine a need to comply with provisions of Clause 6 for the specific areas of the HCF.
First of all, let’s dissect the scope of Clause 6.
Clause 6.1.1 indicates that all its requirements apply to:
(a) the life safety systems that is mandated by the National Building Code of Canada (NBCC) to be provided with emergency power supply (i.e., to the life safety systems defined and described by Section 46 of the CE Code), and
(b) other electrical equipment that is essential for the effective operation of a health care facility during an interruption of the normal electrical supply.
The scope also states (Clause 6.1.2) that in addition to the life safety systems mandated by the NBCC, to the electrical equipment required to provide effective patient care in patient care areas proper, the components of an essential electrical system could be as well outside patient care areas, but in these locations loss of a normal power supply to the electrical equipment may also produce unacceptable risk to the effective and safe care of patients.
So, the scope of Clause 6 advises the users that essential electrical system consists of loads and branches listed in Table 7, and that such loads represent a combination of the electrical equipment comprising "life safety systems” defined and described in Section 46 of the CE Code and electrical equipment essential for care of the patients and for effective operations of the health care facility (i.e., electrical equipment that in addition to life safety systems is also supplied by vital, delayed-vital or conditional branches). Note: Vital, delayed-vital and conditional branches are defined in Z32 and in Section 24 of the CE Code.
Secondly, let’s carefully review Note (1) on the Scope of Clause 6 of Z32 "Essential Electrical Systems.” This Note is extremely important. It advises users of this standard that the essential electrical systems are not intended to be automatically invoked for design and installation of electrical equipment in health care facilities, and that it is up to an administrator of the specific type and class of a health care facility to elect applicability of Clause 6 of Z32 for that particular Class of a health care facility. This means that the extent of the components of essential electrical system in a major hospital would be drastically different from such extent in a typical rehabilitation clinic. Respectively, a health care facility administrator may decide to opt out from electing essential electrical system for a typical dental hygiene or physiotherapy office, etc.
Rule 24-302 of the Canadian Electrical Code re-enforces this fact.
This Rule states the following:
24-302 Circuits in essential electrical systems (see Appendix B)
(1) An essential electrical system shall comprise circuits that supply loads designated by the health care facility administration as being essential for the life, safety, and care of the patient and the effective operation of the health care facility.
(2) An essential electrical system shall comprise at the minimum a vital branch and may also include a delayed vital branch or a conditional branch, or both.
(3) The wiring of the essential electrical system shall be kept entirely independent of all other wiring and equipment and shall not enter a luminaire, raceway, box, or cabinet occupied by other wiring except where necessary
(a) in transfer switches; and
(b) in emergency lights supplied from two sources.
Subrule (1) clearly explains to the Code users that it is up to the health care facility administration to designate loads of the essential electrical system. There are numerous installations where a health care facility administrator chooses to select the loads of the facility entire distribution system as "essential electrical system.” In this case, an electrical designer may (in consultation with the administrator) elect to supply all loads of the health care facility from an emergency generator, and except for a fire pump, all these loads could be supplied via a single transfer switch. Some electrical safety regulators have a tendency to reject such design arrangements, stating that the electrical equipment comprising "life safety systems” described by Section 46 of the CE Code must be wired via a separate transfer switch. Some electrical safety regulators often mandate that conditional or delayed-vital loads must be connected via a transfer switch separate from the transfer switch dedicated to the vital loads. However, such decisions by the regulators who misinterpret codes and standards officially adopted for regulatory purpose could be legally challenged, unless the provisions of Z32 and Rule 24-302(2) are formally amended in their respective jurisdictions.
There are other situations where administrators of jails, colleges or airports would like to consider all loads of those facilities to be designated as essential electrical systems and being supplied with an emergency generator via a single transfer switch. In these cases, electrical designers and the proponents of such approach should communicate their intent with the electrical safety regulators and to demonstrate to the electrical safety authorities that the safety objectives by the relevant codes and standards are not compromised by such proposed distribution arrangements, as the CE Code intent to invoke application of essential electrical system is limited only to health care facilities in conjunction with application of the CSA standard Z32.
So, hopefully, the question raised in the title of this article has been answered.
Read more by Ark Tsisserev
Posted By Thomas A. Domitrovich,
Sunday, July 01, 2012
Updated: Friday, September 07, 2012
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One could argue that due to the technologies on the market, arc flash and other electrical life-threatening events should be rare occasions. But electrical safety is more than just applying a product or sitting through a training class; it’s a regiment of training and procedures implemented in combination with technology that saves lives. There’s no silver bullet for safety. Just like respect, and I don’t mean the respect we should give electricity, safety is earned. Simply attending class and punching your ticket, so to speak, is not enough. An earlier edition of this column gave you a view into arc-flash events from a survivor perspective. One of those individuals attended training classes and was well aware of the dangers of his profession but that was not enough for his safety. You have to implement what you learn. In short, you have to take action. You not only can impact your organization and the projects you work on, you can also impact the codes and standards that set the stage for safety. This article will emphasize your need to work towards safety and to implement what you have learned in your jobs and your lives; it will also help you see how you can get more involved and make an even better and safer electrical industry.
Photo 1. Attending training class is just your first step. You must apply what you learn to realize the value of your education and to keep those skills alive.
Code Development and Adoption
Getting beyond the importance of having codes and standards, we all must do our part and help with their development and adoption. It is important to remember that codes and standards are not developed by the individuals who volunteer to sit on panels; codes and standards are developed by you or people like you that are advocates of safety. Do not lose sight of this fact. It is your input, your proposals, your continued due diligence for safety that creates these documents that we use on a daily basis. The volunteers that sit on code making panels review your input, comment and ultimately either adopt or reject it. What they adopt may be your exact words or some derivative of them. You can’t simply sit back and expect others to improve these documents that you use. Get involved. The NFPA provides you numerous opportunities to propose and comment during a code development cycle on the documents they administer. TheNECjust happens to be one of those documents that you and I use on a daily basis and it just so happens that it is in the middle of a new cycle.NEC2014 is currently being worked on by the 19 code panels that are responsible for all of the chapters of this important document. Your proposals are forming this new document. The Report on Proposals (ROP) document is available at the following URL:www.nfpa.org/70. You can download these documents for free and also download the comment forms to submit comments. NEC 2014 is a baseline for safety and, once released, will be reviewed by states and local jurisdictions for adoption.
Table 1: NEC 2011 Adoption Status with Effective Dates
Don’t be mistaken and think that you only have input to the NEC. You can impact other codes and standards as well. In addition to the numerous NFPA documents, these include but are not limited to the International Code Council (ICC) and Underwriters Laboratories (UL) codes and standards. The codes and standards that you work with on a daily basis have a process for their continued development and a cycle for their revision. Most of these are ANSI documents that follow rules for public input. Your ideas can make these documents even better than they are today.
So let’s take a quick look at the success of NEC 2011 as it moves across the United States. NEC 2011 state-by-state adoption is a very good tale to tell. Table 1 is a list of states who have adoptedNEC2011, including their effective dates. The adoption process for most of these states has been quite uneventful. Some states that have never had a statewide code are in the process of changing that status. Alabama, for example, not shown on the list below as they have most recently adopted NEC 2008 through the adoption of the 2009 International Residential Code (IRC), will now be on a statewide code. It would have been nice to have Alabama adopt NEC 2011 by reference rather than use the IRC version of the document, but it was just not in the cards for that state.
The amendments in these various states are relatively low; especially if you compare them to NEC 2008 adoption success. They range anywhere from removal of GFCI requirements for garage doors and sump pumps (Ohio) to keeping AFCIs on bedroom circuits only (Oregon). AFCI adoption for states on NEC 2011 has been quite successful, with Oregon as the only state that has adoptedNEC2011 keeping AFCIs on bedroom circuits only. That has historically been a practice in that state and old habits are, I guess, just hard to break. The difference between NEC 2011 and NEC 2008 from a financial impact perspective, as reported in an earlier version of this column, is minimal at best. Most of the changes occurred for those areas of the structure that are not basic requirements of a building code. The bigger issue for states these days is not theNECbut rather the energy codes that they must adopt.
The state-by-state adoption of the NEC and other building codes, unfortunately, can be a very political process. A good example of this is currently being played out in the state of Michigan. State-by-state adoption issues have historically been focused on amendments to the proposed code. We’ve typically seen a focus on GFCI, AFCI, selective coordination, tamper-resistant receptacles and other similar sections of the code when it comes to amendments. But just when you thought the controversy would be minimal and adoption of the NEC would go off without a hitch because these areas of the code have little to no change in them, you have a state like Michigan throw yet another kink into your vision by working to extend the adoption process from a 3-year cycle to a 6-year cycle. Pennsylvania is considering the same. Those who try hard to amend the NEC when it is adopted have basically run out of issues to argue. When you have no arguments against a bill at hand, your next strategic move is to implement delay tactics. Many organizations are working together to educate legislatures across the country on why this is not a good idea, but it takes people like you and me to voice our concerns when our state or local jurisdiction decides to make amendments to bare minimum codes. Get involved with your local code adoption process and support timely adoption of the NEC without amendment.
Training and Resources
Training is a fundamental part of safety. It’s not only something you can do on your own but is usually more effective with periodic interaction with other formal programs. If you think that training classes are only good to attend because you need CEU credits for your license, you are mistaken. Seize every opportunity. These training events are not only places where you get your immediate questions answered but also where you build your network of professionals that you can leverage when you have questions later.
Photo 2. IAEI offers many educational opportunities. Attend your local meetings and don’t forget about the Section meetings that occur every year.
Education and networking opportunities are not far away. IAEI provides many opportunities through section meetings and state/local chapter meetings. These events are great opportunities to get updated on latest code changes and code questions, electrical topics like grounding and residential wiring and many other opportunities to network with key individuals.
Trade magazines like IAEI News also provide good information for reference. I personally keep all of my IAEI magazines as well as other trade magazines to which I subscribe filed away not too far from my desk. Another method I use for some periodicals is to snip key articles and file them by topic.
Nothing can replace your network of professionals when it comes to finding answers to your questions. The best place to create that network is at IAEI meetings. Those individuals who attend these meetings love to talk about electrical safety and more often than not are those same individuals that volunteer their time on code panels for the NEC and other key documents we use on a daily basis. Sharing knowledge is the bare minimum we can do to be advocates of safety.
Tools of Safety
There are many products on the market today that can make a difference when it comes to saving life and property from the worst that electricity has to offer. Not all of these tools are products. The following are just a few examples:
Safety Plan — Yes, your safety plan is an important product that you manufacture yourself for your own organization. Just about every presentation and training seminar I personally deliver has time set aside to poll the audience and talk about their safety plan. I’ve had various individuals tell me that they don’t have a safety plan because they do residential work. My response to that is a safety plan is important no matter what market or structure you work in. Put the basics of your plan in your truck to remind yourself on every job. Working de-energized should be at the top of your list.
Personal Protective Equipment (PPE) — PPE is not limited to those big heavy suits that protect you from arc flash. PPE also includes eye and ear protection. We can sometimes forget about these most basic items that protect the most sensitive areas of our bodies. You may not be in front of energized equipment and may in fact be working de-energized but you will still need your eye and ear protection. Every day we experience sound in our environment, such as the sounds from television and radio, household appliances, and traffic. Normally, we hear these sounds at safe levels that do not affect our hearing. However, when we are exposed to harmful noise — sounds that are too loud or loud sounds that last a long time — sensitive structures in our inner ear can be damaged, causing noise-induced hearing loss (NIHL). These sensitive structures, called hair cells, are small sensory cells that convert sound energy into electrical signals that travel to the brain. Once damaged, our hair cells cannot grow back. So how loud is too loud?
110 Decibels: Regular exposure of more than 1 minute risks permanent hearing loss.
100 Decibels: No more than 15 minutes of unprotected exposure recommended.
85 Decibels: Prolonged exposure to any noise at or above 85 decibels can cause gradual hearing loss.
To put this in perspective, the following gives an idea of decibels vs. sound source:
Decibels Sound Source
120 Ambulance siren
110 Chain saw, rock concert
105 Personal stereo system at maximum level
100 Wood shop, snowmobile
90 Power mower
85 Heavy city traffic
60 Normal conversation
40 Refrigerator humming
30 Whispering voice
0 Threshold of normal hearing
Your eyes are yet another sensitive area that must be protected. In many cases, you may not be actually performing the work but still need eye protection. The most basic PPE is not limited to eyes and ears. Don’t forget about your feet and hands and even your knees. Wearing the correct PPE while you work is important no matter what you are doing. Make sure your PPE is up-to-date and on your person — not in the truck.
Ground-Fault Circuit Interrupters (GFCI) — This technology has been around for quite some time and has saved many lives. Job sites that have temporary power have requirements in the code that specifically call out GFCI protection. These requirements are there for a reason. But you don’t have to stop at the bare minimum code requirements. GFCI can provide protection on more than just those circuits in a home that have been called out in theNEC. Going above and beyond is not a code violation.
Arc-Fault Circuit Interrupters (AFCI) — These products too have been around for quite some time and have prevented fires and found many wiring mistakes / damaged conductors and a good number of damaged appliances. This is an unforgiving technology that can detect wiring problems. You do not have to only include these on the circuits that have been identified in the NEC. They can be applied on any 15-A and 20-A circuit and will find the wiring problems that can be detrimental to the occupants of the structure. It’s that electrical inspector that you leave in the load center that keeps an eye out for problems.
Arc Reduction Technologies — Earlier in this article I said, "One could argue that due to the technologies on the market today, arc flash and similar events should be rare occasions.” In addition to GFCI and AFCI solutions on the market, there are many solutions now available that work to reduce the energy on a system when a fault occurs. The NEC now has Section 240.87 that specifically calls out these technologies, or approved equivalent, for certain installations. You can always go above and beyond when it comes to implementing these technologies. Zone selective interlocking (ZSI) and arc flash reduction switches have been used for many years in industrial power systems for certain markets. Now the code is beginning to recognize the value of these technologies and requiring them under certain conditions.
Arc-Resistant Electrical Equipment — Those big grey boxes we live and work with on a daily basis are also now being designed to channel arc-flash energy up and out as opposed to directly in front of the gear where we typically stand and walk. A little thought during the design process can make a big difference down the road when it comes to safety. A little education and awareness go a long way.
Handheld safety equipment — We can’t forget those tools that make it possible to detect problems and also indicate what is energized, keeping us out of harm’s way. These handheld devices are great tools but just as with any product, if you do not apply them correctly, they can be dangerous. Reading instructions and being diligent about how they are used is critical. Misapplied meters and other equipment, handheld or not, may result in disaster. Remember to read the instructions and apply all of your products correctly. These products can be a great asset to your organization. From Infrared cameras to meters, there is a broad range of solutions available that can help detect wiring problems and system issues. They are worth the investment.
The above is just a sample of the various types of solutions available on the market. Simply having these products on your project or in your truck does not mean they will achieve the expected goal. They must be utilized appropriately and included in your safety plans and procedures to be effective.
Procedures in Practice
As noted earlier, electrical safety is more than just applying a product or sitting through a training class; it’s a regimen of training and procedures implemented in combination with technology that saves lives. We can be very knowledgeable and have all of the best safety solutions employed in our facility. We may even have the best that PPE has to offer hanging in a closet or in a bag that is readily accessible. If you don’t make the first move and flex all of this horse power, that investment was all for naught. You must get moving and work to make a safe environment for youself and those around you. Be an advocate of safety by doing the bare minimum — share your knowledge with those around you. Spreading your knowledge just may save a life or keep someone out of the hospital.
As always, keep safety at the top of your list and ensure you and those around you live to see another day. If you have any tips or ideas you would like to share, please feel free to send them to me at firstname.lastname@example.org. I look forward to your input to these articles and guidance for future articles
Read more by Thomas A. Domitrovich
Safety in Our States
Posted By Leslie Stoch,
Sunday, July 01, 2012
Updated: Friday, September 07, 2012
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You probably noticed a number of important changes from 2009 to the 2012 edition of the Canadian Electrical Code. Section 4 – Conductors has taken the lion’s share of the changes. Rule 4-004 has received a good deal of attention. This article discusses and compares some of the similarities and differences between the 2012 version of Rule 4-004 – Ampacity of Wires and Cables and its 2009 predecessor.
Beginning with underground conductors, the 2009 Canadian Electrical Code rule for calculating the allowable ampacities for underground conductors, direct buried or in raceways went right to the point (minimum conductor size #1/0 AWG and allowable ampacities calculated in accordance with the IEEE 835 standard). A "see Appendix B” note led us to an interpretation of the standard — the diagrams and ampacity tables in Appendices B and D. The 2009 rule offered no clues as to what to do about wire sizes smaller than #1/0 AWG or conductor arrangements different from the Appendix B diagrams.
The new Rule 4-004 addresses these earlier limitationsas follows:
Rule 4-004 refers us directly to the conductor configuration diagrams in Appendix B and the allowable ampacity tables in Appendix D;
It tells us what to do if we decide to arrange underground conductors in configurations different from those shown in Diagrams B1 to B4 — allowable ampacities are to be based on the IEEE 835 standard calculation method; and
It tells us what to do for conductor sizes smaller that #1/0 AWG — use Tables 2 or 4 or the IEEE 835 standard calculation method.
Rule 4-004 of the 2009 CEC specified allowable ampacities for single-conductor cables in free air.For cable spacing at least the diameter of the larger adjacent cable, we could use Tables 1 or 3 to determine allowable ampacities for copper and aluminum conductors. For up to 4 single-conductor cables in contact with each other, Tables 1 and 3 ampacities needed to be corrected in accordance with Table 5B. With more than 4 cables in contact, the rule led us to the lower allowable ampacities of Tables 2 and 4.
For single-conductor cables in free air, Rule 4-004 of the 2012 CEC is identical to the 2009 version for spacing apart of at least the diameter of the larger adjacent cable.
But here is where the similarity between the 2012 and the 2009 CEC ends:
For single conductors between 25% and 100% of the larger adjacent cable diameter, we must now use Tables 1 or 3 with correction factors from Table 5D.
For up to 4 single-conductor cables spaced less than 25% of the larger adjacent cable diameter, we must now use Tables 2 or 4 with correction factors from Table 5B.
For more than 4 single-conductor cables spaced less than 25% of the larger adjacent cable diameter we must now use Tables 2 or 4 with correction factors from Table 5C for total number of conductors. (Table 5C correction factors do not apply to runs shorter than 600 mm).
I would be remiss in not mentioning a very important change —new Rule 4-006. This rule requires that when equipment (such as circuit-breakers) is marked for maximum termination temperatures, allowable ampacities must be based on the corresponding conductor temperature columns in Tables 1 to 4. Remember, this applies to both ends of every conductor or cable. If the equipment is unmarked, the 90° C ampacity column applies.
As with earlier articles, you should always check with electrical inspection authority in each jurisdiction for a more precise interpretation of any of the above.
Read more by Leslie Stoch
Posted By Underwriters Laboratories,
Sunday, July 01, 2012
Updated: Friday, September 07, 2012
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Is the XO bonding jumper strap provided in certified (Listed) dry type core and coil transformers used in typical commercial installations adequately sized?Answer
Dry type coil and core transformers typically found in commercial installations are certified by UL under the product category Power and General-Purpose, Transformers Dry Type (XQNX), located on page 452 of the 2012 UL White Book and also on UL’s Online Certification Directory at www.ul.com/database and enter XQNX at the category code search field.
Dry type transformers can have two bonding jumpers installed. One bonding jumper is for grounding the transformer steel core to the enclosure where the core is electrically isolated by the sound dampening pads that are typically made of rubber. This bonding jumper is covered by the requirements in UL 1561, the Standard for Safety for Dry Type General Purpose and Power Transformers 600 Volts or less, and must remain in place.
The other bonding jumper, that may or may not be supplied by the manufacturer, is installed between the XO terminal and the enclosure. This second bonding jumper is identified from the National Electrical Code as the "system bonding jumper.” UL 1561 does not contain requirements to install or size the system bond jumper between the XO terminal and the enclosure or equipment grounding bus. The evaluation of the transformer for Listing, therefore, does not include an evaluation of the size or adequacy for the system bonding jumper; it is really an item optionally provided by some manufacturers. For the same reason, if this bonding jumper were removed because the system grounding and bonding was done elsewhere as allowed by NEC 250.30, the UL Listing of the transformer is not affected. Since the size of the system bonding jumper is based on field-installed feeder conductors for the derived system, it would be difficult to determine the correct size of the system bonding jumper that is to be installed at the factory. If the inspector determines the supplied system bonding jumper does not meet the Code minimum based on the actual installed feeder conductors, then they can require it to be replaced with a suitable system bonding jumper meeting all the requirements from the NEC.
About Underwriters Laboratories: Underwriters Laboratories® (UL) is an independent product safety certification organization that has been testing products and writing Standards for Safety for over a century. UL evaluates more than 19,000 types of products, components, materials and systems annually with 20 billion UL Marks appearing on 66,000 manufacturers products each year. UL's worldwide family of companies and network of service providers includes 68 laboratory, testing and certification facilities serving customers in 102 countries. UL is also the only National Certification Body (NCB) for PV in North America and an OSHA-accredited Nationally Recognized Testing Laboratory (NRTL). For more information, visit www.UL.com/newsroom.
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UL Question Corner
Posted By David Clements,
Sunday, July 01, 2012
Updated: Friday, September 07, 2012
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Never underestimate the value of networking face-to-face! Despite the various ways of communicating — phones, email, instant messaging, social media, faxing, snail mail, telegram, or carrier pigeons — the "time spent interacting in the presence of or in the same location as another or others”1 is still the most productive and valuable. In fact, it is becoming priceless — and rare.
The American Sign Language Association uses "Four Hugs a Day,” a teaching song that demonstrates not only how to sign but also the importance of personal interaction. Inevitably, personal interaction leads to a sense of community, which, in turn, leads to cohesiveness and a common purpose.
IAEI offers face-to-face time to each member and his/her family through the annual section meetings and local chapter and division meetings. From the amount of handshaking and backslapping at these meetings, it is obvious we’ve developed good relationships and a sense of mutual respect and trust, all which are the foundation of community.
As a community, IAEI discusses, first and foremost, the code — face-to-face. Sometimes we get passionate and forceful; sometimes we disagree; sometimes we agree to disagree on code proposals or interpretations of a specific rule. Face-to-face provides the opportunity to debate and discuss inspection challenges, presentations, new ideas and new products.
As a community, IAEI decides which code proposals we will support, based always on whether this change will enhance and increase safety.
As a community, IAEI challenges the merits and safety of new products — representatives, engineers, inspectors, city officials, authors, presenters and whoever is involved face these challenges. Each person is expected to make his or her points clear and concise and in alignment with the code.
As a community, IAEI celebrates the successes and achievements of individual members as well as chapters, sections or divisions; the passage of code proposals; the enrollment of new members.
As a community, IAEI mourns the misfortune, loss or death of any member. We care about those who are ill or facing challenges and we reach out to them.
As a community, IAEI makes the Great North American Educational Adventure. Not all of us can make each event, but we attend as often and as many as we can because we meet up with our friends and their families. We laugh, joke, study, eat, and learn from each other. The program for this year’s educational adventure includes a number of code training sessions and trade shows.
Here are the times and venues for this adventure:
Southwestern Section, DoubleTree Mission Valley, San Diego, CA
Northwestern Section, Hilton Garden Inn, Missoula, Montana
Western Section, Holiday Inn City Center, Fort Smith, Arkansas
Canadian Section, Sheraton Parkway, Toronto, Ontario
Eastern Section, Providence Marriott, Providence, Rhode Island
Southern Section, Astor Crowne Plaza, New Orleans, Louisiana
As a community, IAEI is a group of people interacting with one another remotely and face-to-face and with intense interest in electrical safety. The community affects each other’s abundance, distribution, and career development in the sense that we pass along job openings, recommendations, and share our knowledge of the electrical industry. Whether our units are small and local, state-wide, or regional or global — together we are cohesive and have a common purpose. Together we are stronger than we are individually, especially when we maximize the ability to meet face-to-face.
If you are planning to attend one of the section meetings, or a local chapter or division meeting you will not be disappointed.
If you are not able to attend due to lack of financial support from your employer, approach your supervisor or manager and explain the benefits of being or becoming a member of IAEI and the importance of staying abreast of code and standards and the importance of networking with your peers face-to face.
1 American Heritage Dictionary
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Posted By Stephen J. Vidal,
Tuesday, May 01, 2012
Updated: Friday, September 07, 2012
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Electric machines are very useful and efficient devices which operate through a variety of control circuits. These control circuits are made up ofinputdevices that sense a condition or situation andoutputdevices that make adjustments to change the situation. The symbolic language for this process is calledladder logic. Many of the diagrams used resemble the steps of a ladder; hence, the addition of the word "ladder” into the title.
It is important also to discuss the termlogic. In the study of digital electronics, devices are used that operate in either anonstate or anoffstate. A specialized branch of mathematics called Boolean algebra analyzes this relationship with two numbers — a zero , which represents theoffstate; or a one , which represents theonstate. These two numbers comprise the binary number system.
The most common logic functions areand,orandnot. Think of a single-pole light switch in your home that controls a 100W light bulb. The switch can either beoff oron. Now imagine we place two single-pole switches in series to control the same 100W light bulb. In this condition, switch 1andswitch 2 both have to beon to light the 100W bulb; this is an example of anandoperation (see figure 1). Logic relates to ladder diagrams because input functions in series constituteandoperations, while input functions in parallel constituteoroperations.
Two Types of Ladder Diagrams
Two-wire control circuits
Figure 1. "And” Circuit
You will encounter two types of ladder diagrams: the two-wire control circuit and the three-wire control circuit. The two-wire control circuit is shown in figure 2. This circuit is used to start a motor for some industrial process. The components in a two-wire control circuit are a maintained contact switching device (S1), a relay coil (M1), and the thermal overload relay contact (OL). The sequence of operations is fairly simple when S1is closed, the coil of magnetic motor starter M1 is energized and the motor starts, provided the running overload current is within the value of the overload relay OL. To stop the motor, S1 is simply opened.
Three-wire control circuits
The three-wire control circuit is shown in figure 3. Again this circuit is used to start a motor for some industrial process. The components in a three-wire control circuit are a momentary push-button (STOP), a momentary push-button (START), a normally open relay contact (M1), a relay coil (M1), and the thermal overload relay contact (OL). The sequence of operations here is a little more complex. When the start button is pressed, the coil of magnetic motor starter M1 is energized and the motor starts, provided the running overload current is within the values of the overload relay OL. However, there is one very important difference: a normally open contact of magnetic motor starter M1seals around the start button to latch the circuit. To stop the motor, the STOP button is pressed which, in
Figure 2. Two-wire control circuit
turn, breaks the latch and de-energizes the coil of magnetic motor starter M1; the motor stops.
If you review the traditional ladder diagram of a standard three-wire control circuit as shown in figure 3, you will notice several components: a normally closed stop button, a normally open start button, a normally open relay sealing contact, a relay coil, and a normally closed thermal overload relay contact. This figure also resembles a step ladder with each rung of the ladder representing a specific input or output function, and it demonstrates where the term ladder diagram comes from. Figure 4 provides additional common symbols used in ladder diagrams and motor control circuits.
Momentary contact and maintained contact devices
What components make up a ladder diagram? There are several types of input devices and output devices. For the purpose of this article, we will focus on conventional electromechanical devices. Input devices can first be classified as momentary contact and maintained contact devices. Momentary contact devices are spring-loaded and are classified as normally open and normally closed devices. The designation "normally” refers to the state of the device
Figure 3. Three-wire control circuit
in its resting position when no external stimulus is acting upon it. The contact arrangement of switching devices can also be classified as SPST, SPDT, DPST, DPDT, 3PDT, etc. The first two letters refer to the number of "poles,” and the last two letters refer to the number of "throws.” For example, SPST refers to a single-pole, single-throw contact. 3PDT refers to a three-pole, double-throw contact. A fractional manual motor starter useful for single-phase motors, 1HP and lower, can either be a SPST for 120-V applications, or DPST for 240-V applications. A green start button is an example of a normally open momentary push-button, while a red stop button is an example of a normally closed momentary push-button.
Maintained contact devices are not spring-loaded; they remain in either an on state or an off state. They can also be classified as normally open and normally closed. An emergency stop is an example of a maintained contact device. Temperature sensing devices commonly used are thermostats and thermocouples. A thermostat relies on the thermal expansion/contraction of a bimetal, while a thermocouple relies on a principle known as the Seebeck effect. Two dissimilar metal wires are joined together in a loop with one end being the hot junction and one end being the cold junction. A difference of potential is generated in the loop in response to temperature change. Each of these devices sense temperature change and then presents a contact closure for use in a control circuit.
Motion Sensing Devices
Photoelectric controls and proximity controls
Figure 4. Common symbols [N.O. means normally open; N.C. means normally closed
Motion sensing devices commonly used are photoelectric controls and proximity controls. Early versions of photoelectric controls had an incandescent lamp transmitter and a cadmium sulfide photocell receiver. Modern versions of the photoelectric control have pulsed infrared transmitters and solid state photo-detector receivers. They work on the principle of beam interruption to sense motion and then present a contact closure to the control circuit. Proximity controls sense motion when an object passes by the sensing target on the device. They can detect metallic as well as non-metallic objects. They operate on the principles of magnetism and capacitance, and then present a contact closure to the control circuit. Limit switches are the most versatile device in terms of motion detection. They are available in a variety of operator mechanisms and contact arrangements. They work on the principle of physical contact between an object and the operator mechanism to present a contact closure to the control circuit.
Liquid level sensing devices
The most commonly used liquid level sensing device is the float switch, which operates on the principle of buoyancy. The float is suspended in a liquid bath and as levels of the liquid rise and fall, the float moves. This movement of the float presents a contact closure to the control circuit.
Pressure sensing devices
The most commonly used pressure sensing device is the pressure switch. The diaphragm, or bellows, in a pressure switch monitors the change in pressure and presents a contact closure to the control circuit.
Other types of input devices include the foot switch, the selector switch, or even the contact of a control relay or a timing relay. These are all mechanical devices that present a contact closure to the control circuit.
Outputs of the control circuit can be relay coils, pilot indicating lights, audible devices, etc. To use the generic term relay coil, we need further classification into magnetic motor starter, contactor, and relay. A magnetic motor starter is a relay with a coil and contacts as well as running overload protection by means of thermal overload relays. Bi-metallic thermal overload relays are units made of a heater coil that heats a coil of wire to a specified temperature based on overload current, and a bimetal unit that expands/contracts and operates a contact. Solder pot thermal overload relays use a similar heater coil and a eutectic solder that melts under overload conditions and correspondingly turns a ratchet wheel to operate a contact. The contact arrangement on the thermal overload relay is normally closed but will open under excessive current conditions and de-energize the coil of the magnetic motor starter and consequently disconnect the motor. Contactors are also relays that switch high-load currents but do not provide running overload protection via the thermal overload replay. Control relays are usually designed to switch small control circuit currents. Common types of timing relays are on-delay (delay on operate), off-delay (delay on release), interval delay, and repeat cycle delay. Time delay relays are used for timing in control circuit.
Pilot indicating lights
Pilot indicating lights are used to provide visual indication of a function or verify that a certain operation is either on or off.
Audible sounding devices
Audible sounding devices are used to indicate trouble with a process or alert the user to a particular situation.
Standard motor control circuits will be covered in the next issue.
Read more by Stephen J. Vidal
Posted By Alan Manche,
Tuesday, May 01, 2012
Updated: Friday, September 07, 2012
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GFCI and AFCI protection have both become fundamental safety devices in electrical systems. Understanding the basics of ground-fault protection for people, and arc-fault protection for 15- and 20-amp branch circuits in dwelling units can ensure that your installations are code-compliant and help you in troubleshooting a circuit. As of the time this article was written (late January 2012), the NFPA code-making panels have met to consider proposals for the 2014 NEC. While the 2014 NEC code development process still has a long way to go, a number of GFCI and AFCI proposals are in the works, once again revising where these devices get installed. We’ll discuss a few of them along with some product standard and technology changes.
AFCIs and GFCIs
What is a GFCI?
Do you feel like you have a full understanding of how ground-fault protection works? If not don’t worry about it; we hope this discussion with help you and your co-workers further understand the basics.
There are two different types of ground-fault protection required in the NEC, ground-fault protection for people and ground-fault protection of equipment. Both work in a similar manner, but the protection levels are quite different. We will focus on ground-fault protection for people, provided by a device called a ground-fault circuit interrupter (GFCI). Article 100 in theNECincludes a definition for GFCIs.
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.
The Informational Note describes two very important performance criteria for GFCIs, namely that they will not trip if the leakage current to ground is less than 4 mA and will definitely trip if the leakage current is 6 mA or higher. The 4 mA level is necessary to prevent unwanted tripping due to the natural leakage in appliances, tools and other connected loads, and in the wiring itself.
Figure 1. Effect of current on the human body
The 6 mA must-trip level is important due to the amount of electrical current a human body can withstand without serious physical harm. Although physical effects will vary from person to person depending on whether they are male or female, an adult or a child, in general people will be able to sense electrical currents as low as 1 mA. At about 10 mA they may not be able to "let go” if they come into contact with an energized conductor. Current flow as low as 30 mA may cause breathing difficulty and heart fibrillation in small children. Fibrillation is almost certain for currents in the 100–200 mA range and current over 4 A will cause heart paralysis and tissue burning (see figure 1).
The ANSI/UL 943 standard defines the requirements for GFCI performance in the U.S. and is a tri-national standard, meaning that it is harmonized with CSA C22.2 No. 144.1 in Canada and ANCE NMX-J-520 in Mexico.
How does a GFCI work?
Figure 2. If there is an imbalance, an electronic circuit will determine if the leakage is enough to necessitate an interruption of the current flow.
The operation of a GFCI is really quite simple. It compares the amount of current going out to the load with the amount of current coming back from the load. In a single-phase device both the hot and neutral conductors pass through a current transformer (CT). This is why the load neutral conductor must be connected to a GFCI circuit breaker. If the current going out to the load equals the current coming back, there is no leakage to ground and the output from the CT is zero, but if there is an imbalance, an electronic circuit will determine if the leakage is enough to necessitate an interruption of the current flow, see figure 2.
In a two-pole GFCI circuit breaker, if single-phase (120 V) loads are to be served, both of the hot conductors, and the neutral conductor, must pass through the CT; therefore, the load neutral conductor must be connected to the circuit breaker, see figure 3. Three-pole (three-phase) GFCI circuit breakers are only suitable for protection of a three-phase load; hence, only the three-phase conductors must pass through the CT.
The white "pigtail” wire on a GFCI circuit breaker serves two functions. It completes the connection to the panel neutral bar for the neutral load conductor and also completes the power supply circuit for the electronics. This means that even in installations where there is no load neutral conductor, the white pigtail wire must still be connected to the neutral bar in the load center or panelboard in order for the electronic ground-fault protection circuit to function. (Note: Some manufacturers may offer circuit-breaker GFCIs with a plug-on neutral connection rather than a pigtail.)
What different types of GFCIs are available?
GFCIs are available in two different forms, circuit breakers and receptacles. Circuit-breaker GFCIs are dual listed as UL 489 circuit breakers and UL 943 ground-fault circuit interrupters, see figure 4. Receptacle-type GFCIs are listed as UL 943 ground-fault circuit-interrupter receptacles. The receptacle portion of the device must meet the requirements of UL 498.
In circuit breakers, the main circuit breaker contact(s) perform the interruption task when a ground-fault of sufficient magnitude is detected. In receptacles, a set of contacts performs the interruption task.
The terminals of circuit-breaker GFCIs are marked "Line” and "Load,” so they are not suitable for backfeeding. The terminals of receptacle-type GFCIs are similarly marked to insure that when properly wired the GFCI will also protect downstream receptacles should the installation so require.
Where are GFCIs required?
Figure 3. In a two-pole GFCI circuit breaker, if single-phase (120 V) loads are to be served, both of the hot conductors, and the neutral conductor, must pass through the CT; therefore, the load neutral conductor must be connected to the circuit breaker.
TheNECand Canadian Electrical Code (CEC) require GFCI protection in a large number of applications. The fundamental GFCI requirements are found in Section 210.8 of the NEC, although many other sections require them as well. Suffice it to say wherever electricity may be supplied in a potentially wet location, such as kitchen countertops, near sinks or outdoors, there is a good chance that GFCI protection is required there. A key revision to the 2011 NEC introduced a requirement for GFCIs to be readily accessible for monthly testing. Make sure you keep those receptacles located so as to not create an issue with this new requirement. If you are using a GFCI circuit breaker installed in a panelboard, this revised language is a nonissue.
What’s on the horizon for GFCI Protection?
A proposal to add an auto-monitoring function to the UL 943 GFCI standard is currently being considered by the industry. If adopted, this proposal will require that a GFCI be able to test itself, with the exception of the contact opening function. If a failure is detected, the GFCI will open the contacts (if possible) and deny power to the load. This new function was requested by the US Consumer Products Safety Commission because too few people regularly test their GFCIs. But even with auto-monitoring, users will still need to periodically test their GFCIs to insure that the contact opening function continues to work properly.
What is an AFCI?
Article 100 in theNECincludes a definition for AFCIs.
Arc-Fault Circuit Interrupter (AFCI).A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.
The ANSI/UL 1699 standard defines the requirements for AFCI performance in the U.S. While CSA does certify AFCIs, a CSA standard has yet to be approved.
How does an AFCI work?
The operation of an AFCI is far more complex than that of a GFCI. Note that the NEC Article 100 definition states that an AFCI recognizes characteristics that are unique to arcing. Unfortunately, there is no single characteristic that is unique to hazardous arcs, so an AFCI must look for multiple characteristics, usually occurring at the same time or within a short period of time, to determine whether or not to interrupt the current flow. This usually involves monitoring both the current and the voltage.
Figure 4. Circuit-breaker GFCI certification label
We are using the term hazardous arcs in order to distinguish from operational arcs that naturally occur in an electrical system such as when switches or motors are operated. This greatly complicates the protection task. Not only must the AFCI detect whether arcing is taking place, but it must determine whether it is an operational arc or hazardous arc.
Because of this, the UL 1699 standard is unlike the GFCI or overcurrent protection device standards. In those standards, the device must operate when a specified level of current has been exceeded for a specified period of time. The UL 1699 standard, on the other hand, requires that various types and lengths of cable be intentionally damaged so as to create a hazardous arcing condition that must either be interrupted in a specified period of time or before a fire indicator is ignited.
Further, the UL 1699 standard requires that unwanted tripping tests be conducted using various loads that naturally arc or generate waveforms that might be mistaken for hazardous arcing. Masking tests are also conducted to insure that loads do not interfere with the ability of the AFCI to detect hazardous arcs.
Like in a GFCI, both the hot and neutral load conductors must be connected to the AFCI, and as is also the case with GFCIs, the white "pigtail” wire completes the connection to the panel neutral bar for the load neutral conductor which is terminated on the circuit breaker and also completes the power supply circuit for the electronics. (Note: Some manufacturers may offer AFCIs with a plug-on neutral connection rather than a pigtail.)
What different types of AFCIs are available?
AFCI circuit breakers of 15- and 20-amps are available for installation in load centers and panelboards. They are dual listed as UL 489 circuit breakers and UL 1699 arc-fault circuit interrupters (see figure 5).
Single-pole AFCI circuit breakers are available for 120-V branch circuit protection. Two-pole versions are also available from some manufacturers for the protection of 240 V loads (with common trip) or 120 V shared neutral loads (without common trip).
UL also lists AFCIs and leakage-current detector-interrupters (LCDIs) as a part of cord sets for use on appliances such as window air conditioners to meet the requirement in NEC 440.65.
While UL has a standard (UL 1699A) for outlet branch-circuit arc-fault circuit interrupters (OBC AFCI) and has listed one or two products, as of this writing none are commercially available.
In circuit breakers, the main circuit breaker contact(s) perform the interruption task when an arc fault is detected. In OBC AFCIs or cord-type AFCIs and LCDIs, a set of contacts performs the interruption task.
The terminals of circuit-breaker AFCIs are marked "Line” and "Load,” so they are not suitable for backfeeding.
When AFCI circuit breakers were first introduced, only the branch/feeder type was available. A branch/feeder type AFCI provides protection for parallel arc-faults that occur line-to-line or line-to-ground. The 2005NECrequired the use of combination-type AFCIs beginning January 1, 2008. Subsequent editions of theNEChave required the use of only combination-type AFCIs.
Figure 5. Circuit-breaker AFCI certification label
The UL 1699 standard requires that a combination-type AFCI provide protection against both parallel and series arc-faults. Series arc-faults are those that might occur due a break in a line or neutral conductor.
The certification label on the circuit breaker will identify if it is a branch/feeder or combination-type AFCI (see figure 3). The color of the test button is also a way to identify if a circuit breaker is a GFCI, branch/feeder or combination AFCI; however, as the standards do not define test button colors, each manufacturer has their own scheme for GFCI and AFCI test button colors.
Speaking of test buttons, it is important that users periodically test their AFCIs by pushing the test button.
Where are AFCIs required?
Section 210.12(A) of the 2011 NEC requires arc-fault protection of all 15- and 20-A 120-V branch circuits in dwelling unit "family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas.” Section 550.25 requires AFCI protection in the same rooms in modular and mobile homes. An OBC AFCI may be installed at the first outlet in a branch circuit if a steel wiring method is used to protect the home run or if the home run is imbedded in at least 2 inches of concrete (see 210.12 Exceptions 1 and 2). Exception 3 allows AFCI protection to be omitted if a fire alarm circuit is encased in a steel wiring method.
Section 210.12(B) requires AFCI protection where a 15- or 20-A 120-V branch circuit "is modified, replaced, or extended.”
AFCIs and the 2014 NEC
A couple of key revisions to the NEC-2014 AFCI requirements are being considered by Code-Making Panel 2. The expansion of arc-fault protection to 15- and 20-A branch circuits serving kitchens and laundry rooms has been proposed. It is common to find AFCI protection on at least one of the kitchen branch circuits today when the dining area, which is required to have AFCI protection, is also serving the kitchen.
There is also consideration being given to permit a branch-circuit breaker to provide parallel arc-fault protection for a home run feeding an OBC AFCI installed in the first outlet without being enclosed in a steel wiring means or in concrete. A number of key conditions are essential for this protection system to work based on a recently issued UL research report:
- The instantaneous trip level of the circuit breaker must not exceed 300 A.
- The home run must have a limitation on its maximum length.
- The first outlet box must be identified.
The most significant challenge for this proposal may land in the lap of the contractor and electrical inspector. Will you be able to effectively meet and enforce these parameters? How will you know which circuit breaker has the appropriate instantaneous trip level? (Today, the instantaneous trip level of a branch-circuit breaker is not controlled by a standard and, therefore, can range well above the maximum 300-A level. Indeed, some applications require a higher trip level in order for the loads to operate.) The Code Panel rejected the fundamental requirement for a circuit breaker used in this application to have a Listed marking indicating suitability. How will you know the home run length? How will you know that the OBC AFCI was installed in the first outlet? You may want to review this proposal and provide your thoughts through an NEC comment to the Code Panel.
GFCIs and AFCIs continue to provide the protection envisioned by the electrical industry when they were first introduced in the 1960s and 1990s respectively. Here are a few items to consider as we wrap up this discussion:
- Having a fundamental understanding of the basic functionality of GFCIs and AFCIs will ensure you are not only properly protecting people and the circuit but it also gives you the foundation to figure out why the GFCI or AFCI opened.
- When a GFCI or AFCI opens, always ask the question, "What was it protecting against?” Dismissing the opening as a nuisance trip for either a GFCI or AFCI fundamentally means you just closed the breaker or receptacle back into the same potential hazard if you didn’t address it.
- The requirements for GFCIs and AFCIs continue to be revised in the NEC. Make sure you are keeping up-to-date on the latest requirements.
- Stay engaged with the future development of GFCI and AFCI requirements in the NEC. Provide your input by submitting a comment to NFPA.
Read more by Alan Manche
Read more by Ed Larsen
Posted By Daniel R. Neeser,
Tuesday, May 01, 2012
Updated: Friday, September 07, 2012
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Overcurrent protective device interrupting rating (IR) and equipment short-circuit current rating (SCCR) are key considerations for the safety of commercial and industrial electrical systems. If inadequate overcurrent protective device IR or equipment SCCR is present, a serious potential safety hazard exists. As a result, the NEC and Occupational Safety and Health Administration (OSHA) have added requirements that draw attention to this issue that are resulting in changes to equipment design and specification.
This article focuses on equipment SCCR marking requirements with an emphasis on proper equipment installation requirements according to the NEC.
Unlike the product standards, theNECidentifies the overcurrent protective device IR and equipment SCCR marking requirements. More importantly, it also addresses the installation requirements for proper application of overcurrent protective device IR and equipment SCCR.
It’s important to understand the difference between the IR of overcurrent protective devices (such as fuses and circuit breakers) versus equipment SCCR (such as devices, appliances, apparatus and machinery).
Figure 1. The NEC requires marking of the interrupting rating on a current-limiting fuse per NEC 240.60(C)
IR is defined in the 2011 NEC Article 100 as "the highest current at rated voltage that a device is identified to interrupt under standard test conditions.” Therefore, IR simply is the highest current that an overcurrent protective device is rated to safely clear. According to NEC 110.9, the IR of the overcurrent protective device must be no less than the current available at the equipment’s line terminals.
The NEC requires the marking of the interrupting rating of fuses per NEC 240.60(C) and circuit breakers per 240.83(C) [see figure 1].
Short-Circuit Current Rating
The 2011 NEC Article 100 defines SCCR as "the prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.” Therefore, SCCR simply is the highest current that equipment is rated to safely withstand.
NEC 110.10 requires that the equipment SCCR "be selected and coordinated to permit the circuit protective devices to clear a fault, and to do so without extensive damage to the electrical equipment of the circuit.” Notice thatNEC110.10 indicates that a specific circuit protective device (fuse or circuit breaker) might be required to provide proper protection.
NEC 110.10 also says the protective device must protect the equipment fromextensivedamage. Therefore, damage can occur to equipment after a fault, but it can’t result in a shock or fire hazard outside of the enclosure.
Figure 2. This is an example of marked SCCR on an industrial control panel nameplate
The acceptable damage criteria for SCCR testing and evaluation in product standards is another topic for an in-depth discussion not covered in this article. Typically, acceptable damage might render the assembly or a component in the assembly as useless. The main objective of the product standard SCCR acceptable damage level, however, is to prevent a shock hazard or a fire outside the enclosure.
If a violation of NEC 110.9 or 110.10 occurs, and the fault current exceeds the IR of the overcurrent protective device or the SCCR of equipment, a catastrophic and violent failure of the overcurrent protective device or equipment can occur.
OSHA 1910.303(b)(4) and 1910.303(b)(5) contain similar language to NEC 110.9 and NEC 110.10, so both newandexisting overcurrent protective devices and equipment must have adequate IR and SCCR.
SCCR Marking Requirements
In the past, equipment such as HVAC, industrial control panels and industrial machinery was considered "utilization equipment” and was overlooked regarding proper SCCR and the ability to withstand fault currents. To correct this issue, the 2005NECadded new requirements for marking equipment SCCR to correlate with the product standards.
The 2005 NEC added SCCR marking requirements for motor controllers in NEC 430.8; HVAC equipment in 440.4(B); industrial control panels in 409.110; and industrial machinery in 670.3(A).
In addition, 409.110(3) and 670.3(A) also contained fine print notes (changed to information notes in the 2011 NEC) that UL 508A, Supplement SB was an approved method for determining equipment SCCR for industrial control panels and industrial machinery (see figure 2).
Figure 3. This demonstrates the available fault current and proper application of equipment SCCR.
In the 2008 NEC, Section 409.110 was changed to add an exception that SCCR wasn’t required to be marked on industrial control panels that contain only control components to correlate with the requirements of UL 508A. Therefore, if the industrial control panel contains only control circuit components (components that don’t supply loads such as motors, lighting, heating, appliance or receptacles), then an SCCR marking is not required.
SCCR Installation Requirements
Changes to theNECSCCR equipment-marking requirements were designed to help draw attention to the withstand capabilities of equipment and, combined with the existing requirements of NEC 110.10, prevent installation of underrated equipment.
In the 2011 NEC, additional requirements were added for industrial control panels and industrial machinery that complement and reinforce the requirements ofNEC110.10. Specifically, a new section, 409.22, was added to require that an industrial control panel not be installed where the available fault current exceeds its SCCR as marked in accordance with 409.110. Similar wording was added for industrial machinery per a new section in NEC 670.5.
The added text in 409.22 and 670.5 draws attention to the fact that industrial control panels and industrial machinery must be designed and manufactured with an SCCR that is adequate for the installation.
Therefore, if equipment such as an industrial control panel is being installed in an industrial facility, the system designer must communicate the maximum fault current to the equipment supplier so the supplier can design the equipment with SCCR no less than the fault current where installed in accordance with NEC 409.22 and 110.10.
The process would be similar for HVAC equipment in commercial and industrial building facilities, although not specifically stated other than the requirements of NEC 440.4(B) and 110.10.
Another requirement highlighting proper equipment ratings was added in the 2011 NEC. A new section, 110.24, requires commercial and industrial service equipment to be marked with the maximum available fault current, and to be remarked if modifications of the electrical installation resulted in an increase of the maximum available fault current. The intent of this change was to assure compliance withNEC110.9 and 110.10 for service equipment (see figure 3).
The 2011 NEC changes discussed in this article have helped increase awareness of available fault current and proper equipment SCCR by system designers, installers and AHJs. In many jurisdictions, AHJs have responded to these changes by requiring the available fault current to be documented at equipment and by red-tagging equipment if found with an inadequate SCCR. Because of this, system designers and installers are identifying the fault current at equipment and communicating these requirements to equipment manufacturers.
System designers and installers also are realizing that once the equipment is installed with inadequate SCCR, there are no easy fixes. The only options are equipment modification and recertification or reduction of fault current (through use of additional conductors, isolation transformers or reactors).
Additionally, equipment might be relocated within a facility or to another facility that has increased fault currents, causing additional concerns for flexibility of application for equipment. This can result in costly delays and increased equipment cost.
As a result, equipment suppliers now are being requested to provide equipment with high SCCR. This, in turn, brings equipment design changes to meet the requirements for high fault-current installations.
For more information on industrial control panels and SCCR, see Section 4 of the Cooper Bussmann "Selecting Protective Devices” handbook. Download it free by clicking on the "register for free download links” and submitting the required information athttp://bit.ly/SPDhandbook.
Read more by Daniel R. Nesser
Posted By Don Offerdahl,
Tuesday, May 01, 2012
Updated: Friday, September 07, 2012
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The NEC Code-Making Panels met to act on NEC proposals in January 2012. The results can be found at:http://www.nfpa.org/AboutTheCodes/AboutTheCodes.asp?docnum=70&tab=nextedition.
This is the time to bring comments to the electrical industry by using your IAEI membership. Under the NFPA rules, anyone can submit a comment under his or her own name. IAEI encourages that and does not restrict, in any way, anyone wishing to make such submissions.
If the individual also wishes to have IAEI endorsement, in addition to submitting the comment himself or herself, then that person must work through the local chapter or division to start the process. IAEI encourages the chapters and divisions to work cooperatively to develop good code comments. These groups can discuss and refine the proposed language and be sure the technical substantiation is complete and that it solidly supports what is being proposed. Comments may start with a voice of one, but they get stronger and gain power with support and input of many. When accepted by the chapter, it will be submitted to the section as a chapter-accepted IAEI comment. When chapters and divisions have their meetings, this is when the membership of the chapter or division needs to act on any comments to move forward.
The next step is at the section level. Based on policies set by each section, chapters and divisions can submit their proposals to the section for consideration. The Section Codes and Standards Committee will complete a review and then make a recommendation to the membership at the section meetings in September and October of this year. The section needs to receive these comments in time to meet two deadlines.
The first deadline is so the Section Codes and Standards Committee will have the opportunity to review, meet, discuss, and provide a recommendation to the membership to vote on. Most of the sections have set dates in the August timeframe, so check with your section secretary to find out what the deadline is.
The second deadline is for the IAEI International Codes and Standards Committee. This committee needs all comments that might become IAEI-endorsed to be at the IAEI International Office on or before September 1, 2012. This date is set so the Codes and Standards Committee can review the comments and then take final action once all the sections have completed their actions.
It is important to understand that the role of the Codes and Standards Committee is to review what was submitted and to make recommendations, based on the merit of the submission, to accept to go forward or to reject, and not to write comments.
The international president, in accordance with the international bylaws, has appointed the members to the International Codes and Standards Committee. This committee will receive comments from the sections only. Comments cannot be submitted by individuals to the international level. If the section acts favorably to forward comments submitted to them for consideration as an IAEI organizational submission, then the committee will review the comments in their entirety and if found acceptable will have the CEO/executive director submit the IAEI-endorsed comments to NFPA.
IAEI has two representatives on each code panel and they will be instructed to be advocates for IAEI proposals and comments as submitted by the international CEO/executive director. Having a voice at the panel ensures that the proposal gets considered and discussed fully by the panel.
Now is the time to get involved with your local chapter or division.Being involved with the code change process is one of the benefits of being a member of IAEI and getting involved now can make your job easier and more productive in the future.
Most section comments due. Verify what your section deadline is.
September 1, 2012 5 p.m. CST
Comments to be IAEI-endorsed due at International Office
October 17, 2012
NFPA closing date for NEC comments
Read more by Don Offerdahl