705.31 gone/moved in the 2020 nec

[ggunn]

I don't have a 2020 codebook, but a colleague tells me that 705.31 (the language about a supply side inverter interconnection having to be 10' or less from OCPD) is no longer there in the 2020 NEC. Has it been moved or removed? Where to or why?

 

[wwhitney]

FWIW, you can read the 2020 code oneline: go to www.nfpa.org/70 and choose "Free Access" next to "View this Document" You can pick from the last several versions to view. A free account is required.

Cheers, Wayne

 

[wwhitney]

I don't have a 2020 codebook, but a colleague tells me that 705.31 (the language about a supply side inverter interconnection having to be 10' or less from OCPD) is no longer there in the 2020 NEC. Has it been moved or removed? Where to or why?

Oh, and since I had it open, I looked this up. There is a new section 705.11 titled "Supply-Side Source Connections" which I didn't read but looks like 705.11(C) is the new location of the language you mention. 705.12 is now titled "Load-Side Source Connections".

Cheers, Wayne

 

[Carultch]

The 10 ft rule still applies to some supply-side connections in dwelling units. This rule became more permissive to also allow lengths up to 15 ft on services other than a dwelling unit, and the ability to use cable limiters in the event you need to go even farther.


The rule is in a more logical place in the NEC, put with 705.12(A) that used to not give you very little guidance at all on how to do a supply-side interconnection. It just said that you could, and that your capacity couldn't exceed the service rating. No guidance on how to classify the supply-side interconnection conductors, and you had to go all the way to 705.31 to find the length limit. At least now the length limit is in an easier to find location, and acknowledges that 10 ft just may not be practical in large commercial applications.