AFCI Update

By Tom Baker, Mike Holt Code Forum Moderator

As a code forum moderator, I see various forum posts and note the trends of them. Early in 2001 there were a lot of posts on AFCI’s such as:

Are AFCI’s required for smoke detector outlets?
Why does my AFCI trip when I turn on this light?
Will the AFCI nuisance trip?

Recently, the number of AFCI posts has dropped off considerably. I haven’t noted one for several weeks, one today was if AFCI’s are required for a panel change out.

Comments on AFCI installations:
Early on I did not realize that all AFCI’s have a built in Ground Fault Interrupter, set at 30 mA to 50 mA. This is not a “Class A” GFCI, but functions in the same way. Many of the installations where an AFCI trips is not due to the Arc Fault portion tripping, but rather an inadvertent neutral to ground connection. We had the same tripping of GFCI’s when they were first installed, due to the same conditions. GFCI’ and now AFCI’s have shown there are miswired and inadvertent neutral to ground connections.

At least one manufacture makes a listed combination AFCI and GFCI circuit breaker. This device sells for about $38 and offers a lot of protection for the money.

One comment that came up on the forum is the AFCI generates heat and if multiple AFCI’s are to be installed in the same panel, they need to be spaced out to reduce heat build up. However this is not necessary, as current loading primarily determines an AFCI circuit breaker’s temperature.

New Products
Several new products were introduced as a result of the AFCI. Insulated staples were marketed to reduce damage for over stapling NM cable. 12-2-2 NM “Romex” was introduced to allow home runs for two AFCI circuits, as an AFCI can not have a shared neutral (due to ground fault protection). However, at least
one manufacturer (Cutler Hammer) offers a 2-pole AFCI for home runs. Standard 12-2-1 NM “Romex” can be used. The 2-pole AFCIs are available with/without common trip for overcurrent and overload conditions; the trip is always common for an arcing or ground fault.

Testing AFCI’s
An AFCI can be tested by using the built in test button. This tests the internal circuitry but not the wiring. AFCI manufactures literature states the branch circuit can be tested using an Insulation Tester (Megger), but an insulation tester can be used to test any circuit prior to being energized, AFCI or not. One testing suggestion was to connect a 100 watt lamp as a load and energize the circuit (this would be at rough-in). With the lamp load this will detect a “shared” neutral condition.

One That Works, One That Was Recalled
A tester was introduced by Etcon AF120 claming to be an “AFCI Tester” it actually (if you read the fine print and knew how an AFCI worked) only tested the GFP portion of the AFCI. And this product was subject to a recall by UL, as it was illegally labeled “UL Listed”

Fox Meter Inc introduced a true AFCI tester (now UL Listed). I have not seen it or know of anyone who has, but the initial review is promising. If you’ve used one, please let me know. A recent post on the Code Forum indicated Etcon is developing an AFCI tester that uses an “Arc” to test the AFCI.

The Future of AFCI
Certainly there will be more requirements for AFCI installations in the 2005 NEC. Proposals for the 2005 NEC included voluminous documentation and endorsements for AFCI’s. While the requirements for AFCI’s may be felt by some to be forced upon the industry by special interest groups, the AFCI is here to stay.

More information on AFCI’s is available at:

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