Arc fault conduit

[jcahill (John Cahill, TREC 855)]

Texs standards exclude arc fault on conduit systems.

Does NEC support that?

Why is it not required?

[rmeier2 (Robert Meier)]

This is from the 2008 NEC:

210.12 Arc-Fault Circuit-Interrupter Protection.
(A) Definition: 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.
(B) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination-type, installed to provide protection of the branch circuit.
FPN No. 1: For information on types of arc-fault circuit interrupters, see UL 1699-1999, Standard for Arc-Fault Circuit Interrupters.
FPN No. 2: See 11.6.3(5) of NFPA 72®-2007, National Fire Alarm Code®, for information related to secondary power supply requirements for smoke alarms installed in dwelling units.
FPN No. 3: See 760.41(B) and 760.121(B) for power-supply requirements for fire alarm systems.
Exception No. 1: Where RMC, IMC, EMT or steel armored cable, Type AC, meeting the requirements of 250.118 using metal outlet and junction boxes is installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a combination AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.
Exception No. 2: Where a branch circuit to a fire alarm system installed in accordance with 760.41(B) and 760.121(B) is installed in RMC, IMC, EMT, or steel armored cable, Type AC, meeting the requirements of 250.118, with metal outlet and junction boxes, AFCI protection shall be permitted to be omitted.

The use of RMC, IMC, EMT or steel armored cable, Type AC, meeting the requirements of 250.118 is permitted for the homerun from the OCPD to the first outlet. At that outlet you would need to install a combination AFCI device to protect the rest of the circuit.

[Jim_Port]

The exception would be hard to satisfy and would only cover from the panel to the first device on the circuit. AFCI protection would then be required. AFAIK, the device type AFCI has not made it to market yet.

IMO that is an incorrect interpretation of the requirements.

[mboyett (Michael Boyett, TREC #7290 (Ret) Boerne, TX)]

John…I fought this battle when the new TREC SOP was being drafted. Clearly, I lost that battle as BM interpreted the requirement as he saw fit.

Here’s the communication I had with the IAC (could be considered a 1st generation RFI):

AFCI memo.pdf (103 KB)

[jcahill (John Cahill, TREC 855)]

Thanks Mike, I have a group interested in helping us this and they are “bonafied”. Will explain who in private email.

[rmeier2 (Robert Meier)]

I always thought that this was one of the better written NEC code sections. I’m surprised to hear that someone is interpreting this to not require AFCI protection when using conduit.