This article was posted 03/20/2012 and is most likely outdated.

Mike Holt - An insider’s look at the NEC Code making process as it related to AFCIs
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An insider’s look at the NEC Code making process as it related to AFCIs

An insider’s look at the NEC Code making process as it related to AFCIs

Written by Dr. Joe Engel Image

All new home branch circuits are required by Code to be electronically protected, either by Ground Fault Circuit Interrupters (GFCIs) or Arc Fault Circuit Interrupters (AFCIs). Areas including kitchens, bathrooms, garages, etc. must be protected by GFCIs, while living areas must be protected by AFCIs. The AFCI is the fourth generation in residential branch circuit protection after fuses, circuit breakers, and GFCIs.

National Electrical Code in 2002 first added AFCI protection, for bedrooms outlets. In 2008, coverage was expanded to all living areas, also adding that only “Combination AFCIs” are allowed. Manufacturers and UL today claim that arcing across a break in a cord’s conductor is hazardous, and that a Combination AFCI will respond to prevent a fire.

A typical claim from a manufacturer’s web site:

“A series arc is an arcing incident across a break in a conductor. A common example is a cut across one of the two wires in a lamp cord, with a dangerous arc forming in the gap. Combination AFCI circuit breakers detect the arcing condition and turn off the circuit, thus providing the enhanced protection.”

When today’s Combination AFCIs were tested for response to series arcing in cords, as claimed by the manufactures, their trade organization NEMA, and UL, they didn’t respond. How can this be? Would the now disallowed Branch/feeder provide more protection at less cost?

If you'd like to test your knowledge of the Combination AFCI circuit breaker, please try answering the following true/false questions.

1. The Combination AFCI, first mandated in NEC 2008, provides more fire protection than the earlier AFCI.
2. The Combination AFCI combines both ground and arc fault protection.
3. The Combination AFCI combines both parallel and series arc protection.
If you answered “true” to any of these questions, you may want to look at this web site.

The answer to these questions may be found on my web site http://www.combinationafci.com

About the Author: Dr. Joe Engel worked as an electronic/electrical circuit designer/manager at Westinghouse’s Science and Technology Center, Pittsburgh PA from 1963 to 1993. From 1993 to 2007 he managed Eaton | Cutler-Hammer’s Electronic R&D Department. He served as a member of numerous IEC, NEC, UL, and SAE panels. He holds over 100 US Patents.

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Comments

  • This is the first time I have read a description of how these devices work. I work in Washington State, which has refused to require AFCI's for other than bed rooms. An inspector told me that the state is under pressure from insurance companies for this reason. Maybe it is time for AHJ's to exempt the "Combination" requirement until manufacturers can justify a need, other than greed. UL and NEC requirements only become law when governments rubber-stamp them.

    D Bailey  March 23 2012, 12:35 am EDT

    • Reply from: Joe Engel   April 1 2012, 9:53 am EDT
    D Bailey’s suggestion that AHJs should be made aware of the “combination” controversy is valid and warrants further discussion and actions. I'm focused on pressuring the NFPA Code Panel 2 to vote in favor of my proposal to strike the words "combination type" from paragraph 210.12(A).

    I’ve made important progress; the Panel agrees with my two basic claims: 1. Arcing across a break in a conductor cannot start fire, and 2. Combination AFCI will not respond and trip.

    The Panel Statement in response to my proposal (2-88 Log #2099 NEC-P02): “Replication of the experiments shown in the video shows that there is minimal actual arcing occurring. When arcing does occur, causing the sparking seen in the video, its duration is very short and the energy is three orders of magnitude below what is required to ignite the NM cable or surrounding materials. The waveform looks the same as when a wall switch is switched on and off. If the AFCI responded to this waveform it would increase the incidence of unwanted tripping while not contributing significantly to mitigating fire hazards.” http://www.nfpa.org/Assets/files/AboutTheCodes/70/70_A2013_NEC-P02_ROPballot.pdf

    The Panel supported their conclusion with test data. I applaud the Panel for conducting the test and publishing results on their NFPA web site. The Panel now directly contradicts claims such as Square D’s: “A series arc is an arcing incident across a break in a conductor. A common example is a cut across one of the two wires in a lamp cord, with a dangerous arc forming in the gap. Combination AFCI circuit breakers detect the arcing condition and turn off the circuit, thus providing the enhanced protection.”

    Oddly, by voice vote, the Panel rejected my proposal. I feel that the Panel will reverse itself when members recognize that claims of a Combination AFCI over the Branch/feeder AFCI are false, perhaps fraudulent. Branch/feeder AFCI provides more protection at less cost ($17 versus $37), if allowed they would save lives.

    I’ve added the slides that I used during my IEEE paper presentation February 3rd 2012 in Daytona Beach to my web site.

    Slide 30 describes the Panel’s rejection of Combination AFCI’s claims regarding series arcing; slide 21 begins my discussion of the issues involving false advertising (fraud).

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