AFCI Breakers NEC 705.12(D)(6) 2014 Question

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deadshort

Member
Location
Nor Cal
So we just failed an inspection because of an inspector's interpretation of NEC705.12(D)(6) "Wire Harness and Exposed Cable arc-Fault Protection- A utility interactive inverter(s) that has a wire harness or cable output circuit rated 240V, 30 Amperes, or less, that is not installed within an enclosed raceway, shall be provided with listed ac AFCI protection."

It is an ACPV system. We used MC cable from the j-box on the roof to the tie-in in the main service panel which was up to spec and he had no problem with that portion.

He called us out for the WIRE COMING OUT OF THE MICROINVERTER TO THE J-BOX. Has anyone else ran into this? Is there a caveat because this portion of the circuit is on the roof and NOT running through the building?

There doesn't seem to be a way to enclose this portion of the circuit in conduit because it would require modifying the cable and housing of the micro-inverter itself which would void the manufacturer's warranty.

Simply installing an AFCI breaker is not an option as Siemens/Murray is the only manufacturer that makes a backfeed-rated breaker and it is pretty pricy and this is not a Siemens panel.

Need help as a huge portion of our jobs are AC modules these days and this kind of crazy enforcement will bring us to a standstill!

Thanks.
 
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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
You might try the argument that the wire (whip) factory attached is part of a UL listed assembly and not field wiring. As such it is not subject to the NEC.
If he applied his argument to a trunk cable supplied by the inverter manufacturer, I do not think you would be on equally strong ground, even though it is also UL listed. It is a separate part that I would consider exactly covered by the "harness" part of the code section.
If he holds his ground, you may only be allowed to use microinverters with built in AFCI.
Good luck!

Sent from my XT1585 using Tapatalk
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Tell him if you would be happy to comply if you could find an AFCI breaker is suitable for backfeed as required in 704.12(D)(4). Tell him the entire solar industry is unable to comply with this provision because the right products don't exist, and point out the third paragraph of 90.4. This was a situation where the manufacturers told the code making panel back in 2013 they'd have no problem producing these products and then they weren't actually able to. Hence the TIA that shortcircuit already mentioned.
 
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deadshort

Member
Location
Nor Cal
Thanks everyone. The course of action seems pretty clear; plead logic to the AHJ and make them aware of the TIA.
We'll hope for the best.
 
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deadshort

Member
Location
Nor Cal
So this was resolved with the AHJ (at least this one) after presenting the TIA article for their review. They agreed to not enforce NEC 705.12(D)(6) as it will be removed from the next code iteration. Hopefully this can help others if they run into this same problem.

That was a close one!
 
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