I just ran a circuit for a 30 amp 240 V A/C unit. The GC and crew intalled the unit. It has an AFCI on the cord. As soon as it is plugged in, the AFCI trips and won't reset. My question is, can the cord mounted AFCI detect an upstream fault? Or is it just for a fault in the unit and cord?
Not that I think I have a fault, the circuit is 40 feet in pipe with #10 THHN. There is only one splice and I checked it. I pulled a ground to the junction 6 feet away from the unit, then used the pipe from there since it is indoors with set screw connectors. I jumpered to the receptacle. The ground tests fine at the unit, altho I don't think it would matter anyway to the AFCI.

I just want to be ready in case the GC blames my wiring. Thanks........B

BigB,

I always run a ground wire, when using EMT, or any loosley connected system.

Yes I almost always do too but in this case I don't consider a six foot length of emt with set screw connectors in an area not subject to damage as loosely connected. I was keeping pipe fill down.
But there has been many posts on this subject, I really wanted to know if the AFCI could see an upstream problem or not.
Would an emt grounding path make the AFCI trip?

Also, this morning the AFCI didn't trip, but the unit would not start either.

OK Big B, I really dont think the AFCI will detect an "Up-stream" defect. But the big question here is, what the heck is a AFCI cord cap doing on an AC unit? Is this in a bedroom? I really don't think I have heard about them being required on them. Was this an aftermarket install by others? As I have had serious problems with motors or capacititive type equipment on AFCI's, I doubt one would last long on an AC unit. Anyway, is this thing a 3-wire, or 4-wire? Is there any ground and neutral continuity at the plug, or the unit? That would trip it, simularly to a GFI.

440.65 Leakage Current Detection and Interruption (LCDI) and Arc Fault Circuit Interrupter (AFCI).
Single-phase cord-and-plug-connected room air conditioners shall be provided with factory-installed LCDI or AFCI protection. The LCDI or AFCI protection shall be an integral part of the attachment plug or be located in the power supply cord within 300 mm (12 in.) of the attachment plug.

e57,
It's a 3 wire, no neutral. I am convinced it is the AC unit (Brand new Carrier) or the AFCI itself that is faulty. It wouldn't even stay set the first day, now it stays set but the unit still won't even attempt to start, no fan, no nothing. I told the GC today my circuit is ok, it's his unit. He called his service people to come and check it out.

440.65 ?!? There's a new one for me... Leakage I can see, but AFCI? Have had serious problems with motor loads on them, and can not see an AFCI working well with an AC unit. Then again, it rarely makes it over 70 here, AC is often for points south or north of me....

I just read 440.65 and i too am pretty surprised to see that requirement, as i had always been told not to connect motor loads to AFCI because there would doubtless be tripping. In fact, on my most recent project in a HUD housing complex, the engineer had specced the kitchen garbage disposal to be AFCI-protected. We rolled our eyes and the foreman agreed to override this spec (after a perfunctory RFI, I'm sure).

440.65 does not belong in the code since it really is a national testing laboratory standard kind of thing.

This requirement can never be part of the field wiring which is the purview of the NEC.

It creates a standard for single phase air conditioners, not the structure.

I would move to have it stricken from the next code on the basis that it is beyond the ambit of the NEC.

It sounds like some manufacturer of AFCI OEM devices hustled this through the code committees without it getting enough thought.

The current requirement for AFCI cicuits in bedrooms just makes the cord embedded device redundant.