Electrical Fire Prevention - Section 210.12 of the NEC

Posted in: Features, January/February 2014

book_insights.pngThe story of the arc fault circuit interrupter (AFCI) is an interesting one as it is technical in nature, wrapped in controversy, fueled by passion, and delivers a positive electrical safety impact to the electrical industry. The 2014 National Electrical Code® (NEC) again modified Section 210.12, expanding AFCI coverage and providing more options. When you open your code book to Section 210.12 this year, don’t let the size of the section intimidate you. It’s not all that big of a change.

From an NEC perspective, it was during the NEC 1996 development process that the need for this technology was identified to the electrical industry through the NFPA 70 development process. Proposal 10-97 brought forth the following proposed language:

“Section 240-83 (f) Circuit Breakers In Dwelling Units. (New title & text.) Circuit breakers for 15A and 20A branch circuits supplying receptacles in living and sleeping areas of dwelling units, in accordance with Section 210-20 (b), shall be listed and shall be marked ‘LIT’ (low instantaneous trip).”

The submitter shared Consumer Products Safety Commission (CPSC) data of fire statistics and study information that was used as the foundation for the work that Code Making Panel (CMP) 2 continues to this day. The submitter of this proposal was seeking to achieve the goal of arcing fault protection noting in the substantiation that, “Evidence exists that present safety standards and national codes do not adequately address the risk of fire resulting from arcing shorts in branch circuits, fixture wiring, extension cords, and power supply cords (i.e., the power supply system).”

The panel rejected this proposal with a panel statement that, “The substantiation included with the proposal is insufficient to show that lowering the instantaneous trip levels will adequately address fires due to low level arcing faults in damaged appliances and extension cords. A more complete analysis of cord problems and alternate solutions, such as alternate cord constructions, supplemental overcurrent protection, reduced appliance inrush, and electronic sensing means is needed. Mandating these lower instantaneous trip levels will result in a false level of security from arcing faults. The submitter has not provided any compelling evidence to show that existing branch circuit overcurrent protection devices do not protect premises wiring as required in Article 240.”

In the historical documents around this topic, it is quite clear that the molded case circuit breaker, listed to UL Standard 489, “Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit- Breaker Enclosures,” was under the microscope; in some cases identified as devices that are not performing as they should. The electrical industry, including manufacturers, standards developers, and other experts, began the process to create the standard for the device that would address the identified problem, the electrical fire. The process included more studies, research, and fire data, and the final product is what we know today as UL 1699 “Arc-FaultCircuit-Interrupters.” You can trace the origins of this UL standard to 1997, shortly after the code panel debates and introduction of the electrical fire problem to the electrical industry.

Important lessons can be learned as a result of the debates around this topic. Many people thought, and probably some still do today, that a standard thermal magnetic circuit breaker protects all wire in the circuit from all types of faults, even those wires that are plugged into receptacles. Some that are quite familiar with the NEC will point out Section 210.20, “Overcurrent Protection,” which states, “Branch-circuit conductors and equipment shall be protected by overcurrent protective devices that have a rating or setting that complies with 210.20(A) through (D).” This section has to be read in its entirety to understand that the overcurrent protective device is there to protect the wire behind the walls. The outlet devices, flexible cords, and fixture wires are not afforded overcurrent protection as part of this section by the upstream circuit breaker.

As pointed out in Section 210.20(B), “Conductor Protection,” flexible cords and fixture wires are provided protection as part of Section 240.5, “Protection of Flexible Cords, Flexible Cables, and Fixture Wire.” Supply cords of listed appliances or luminaires are considered protected where the flexible cord or tinsel cord is approved for and used with a specific listed appliance or luminaire when applied within the appliance or luminaire listing requirements. The flexible cords used in extension cord sets are considered protected when applied within the extension cord listing requirements. Combination-type AFCI devices provide additional protection of installed wiring and extends protection to connected cords. One could argue that these devices provide protection for connected appliances as well as evidenced by various product recalls due to the AFCI identifying the problem and tripping.

It was the 1999 NEC that first introduced the AFCI. In the proposal phase of the process, Proposals 2-128,2-129, and 2-130 were those that introduced this technology to CMP 2. The comment phase saw a total of 30 comments, comments 2-55 through 2-85. It was in comment 2-56 where the proposer pointed out that, “Arc-fault circuit interrupters protection was proposed for the 1996 NEC but was not labeled as such in the Report on Proposals Reports of the 1995 meeting for the 1996 NEC Proposal 10-97(240-83(f))(new) Log No. 2066. I supported its use then and now . . . I am in general agreement with the comments of Proposals 2-128,2-129, and 2-139 of the 1998 Report on Proposals and believe this should become a NEC requirement.”

The 1999 NEC began the history of AFCIs in the NEC with the following language.

“210-12.Arc-Fault Circuit-Interrupter Protection.

(a) Definition. An arc-fault circuit- interrupter is 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.

(b) Dwelling Unit Bedrooms. All branch circuits that supply 125-volt, single- phase, 15- and 20-ampere receptacle outlets installed in dwelling unit bedrooms shall be protected by an arc-fault circuit interrupter(s). This requirement shall become effective January 1, 2002.”

And it has been changing ever since.

This code cycle appears to have made a lot of changes to Section 210.12 of the NEC, but in reality we have some expansion, three more options to achieve protection of the entire branch circuit and connected cords, and some reorganizing. Let’s examine these changes one at a time.

1. Expansion

nec_changes_insights.pngSection 210.12 (A) now includes AFCI protection requirements for kitchens and laundry areas. These two new areas of the home are unique in that they also have requirements for ground fault circuit interrupters (GFCI). Combined with a requirement that both the AFCI and the GFCI must be readily accessible, it makes for a challenge to address such appliances as dishwashers, garbage disposals, and even refrigerators where they are within six feet of the edge of a sink. Providing solutions that are readily accessible may be challenging but not impossible.

Another subtle expansion in this section of the NEC is the addition of the words “or devices” to the first sentence of this requirement. The new language reads, “All 120-volt,single-phase, 15- and 20-ampere branch circuits supplying outlets or devices . . . ” require AFCI protection. This impacts those switches, like a light switch, that may be located in one of the rooms that have this requirement. A good example would be a light switch in the kitchen that controls outside lights. AFCI protection would be required for that branch circuit, which essentially expands AFCI in this example to the outside lighting.

Another area of expansion included a new requirement for dormitories. Section 210.12(c) was added noting, “All 120-volt,single-phase, 15- and 20-ampere branch circuits supplying outlets installed in dormitory unit bedrooms, living rooms, hallways, closets, and similar rooms shall be protected by a listed arc-fault circuit interrupter meeting the requirements of 210.12(A)(1) through (6) as appropriate.” Dormitories are those college and similar rooms that house students. These are little living areas that have some of the comforts of home and many more additions by the students themselves who can at times be quite creative. Fire statistics drove this new requirement as well.

2. New Options

The presence of a receptacle-type AFCI device, an outlet branch circuit (OBC) AFCI, on the market is driving the need to define additional options for the application of these products in new construction ensuring equivalent protection of the entire branch circuit and connected cords. The OBC AFCI device does not offer the same level of protection as the combination-type AFCI circuit breaker. The CMP wanted to ensure an equivalent provision for the proper application of these devices. The following three options were added to 210.12(A):

(2) Listed branch/feeder AFCI circuit breaker with an OBC AFCI device at the first outlet. There are no restrictions when these two devices are used together other than the OBC AFCI device must be at the first outlet, and the first outlet box in the branch circuit must be marked.

(3) A listed supplemental arc protection circuit breaker with an OBC AFCI device at the first outlet with the following restrictions for the application:

a. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch-circuit AFCI.

b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 feet) for a 14 AWG conductor or 21.3 m (70 feet) for a 12 AWG conductor.

c. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.

(4) A listed OBC AFCI installed at the first outlet on the branch circuit in combination with a listed branch-circuit overcurrent protective device with the following restrictions for the application:

a. The branch-circuit wiring shall be continuous from the branch-circuit overcurrent device to the outlet branch- circuit arc-fault circuit interrupter.

b. The maximum length of the branch-circuit wiring from the branch-circuit overcurrent device to the first outlet shall not exceed 15.2 m (50 feet) for a 14 AWG conductor or 21.3 m (70 feet) for a 12 AWG conductor.

c. The first outlet box in the branch circuit shall be marked to indicate that it is the first outlet of the circuit.

d. The combination of the branch-circuit overcurrent device and outlet branch-circuit AFCI shall be identified as meeting the requirements for a system combination type AFCI and shall be listed as such.

Of these new options, at the time of this writing, the branch/feeder AFCI solution is the only one for which listed products exist. The standards behind the products for options (3) and (4) are still under construction. When leveraging options (3) and (4) above, the restrictions are important to observe, understand, and follow. Electrical inspectors will be looking to ensure each of these restrictions are in place.

The key takeaway here is that for AFCI solutions, the OBC AFCI and the combination-type AFCI circuit breaker are the two work horses of AFCI protection. You can use them both in new construction today. When applying the OBC AFCI receptacle-type device, care must be taken to ensure you meet the requirements of the code. The provisions for the OBC AFCI that have been in the code remain as options instead of exceptions. Options (5) and (6) are what we used to know as exceptions in previous editions of the NEC and can be leveraged today for the application of the OBC AFCI device.

The AFCI is a device that is technical in nature, wrapped in controversy, fueled by passion, and delivers a positive electrical safety impact to the electrical industry. For examples of found electrical problems, visit www.afcisafety.org often as there is a document on that website that provides examples of found electrical problems. Together we can make a difference.

Thomas Domitrovich, P.E., is a National Application Engineer with IEC Platinum Partner Eaton Corporation in Pittsburgh, Pennsylvania. He has more than 20 years of experience as an Electrical Engineer and is a LEED Accredited Professional. Domitrovich is active in various trade organizations on various levels with IEC, International Association of Electrical Inspectors, Institute of Electrical and Electronic Engineers (IEEE), National Electrical Manufacturer’s Association (NEMA), and the National Fire Protection Association (NFPA). Thomas is involved with and chairs various committees for NEMA and IEEE and is an alternate member on NFPA 73. He is very active in the state-by-state adoption process of NFPA 70, working closely with review committees and other  key organizations in this effort.