Things that make you go "Huh?"

[ggunn]

We have a customer who wants to connect a PV system to a subpanel in a garage. The sub is supplied by a 100A breaker in the main and connected to the main with AWG #6 copper. There is no ground wire run from the main to the sub and there is no ground rod at the garage. All the neutrals and grounds for the garage land on the same bar in the subpanel enclosure, which is isolated from the enclosure.

Huh?

 

[Smart $]

Used to be you could power another building or structure without running an EGC... just use the grounded conductor for bonding on the line side of the building disconnect... business as usual on the load side the same as a service panel (though technically non-compliant).

The #6 100A feeder and no GES to my knowledge have always been violations.

 

[jaggedben]

I've run into this sort of thing. With the AHJ's I've discussed it with, it has come down to the following: if there is documentation that the existing installation was permitted and passed inspection, then you can use it as is. If not, you'll be digging up the ground (or at least you'd better be prepared to, even if you think you have strategy to avoid it).

In this case since the neutral is isolated and there's no grounding electrode, you'd have to fix those things. Oh, and the OCPD. Yeah. Those things don't bode well for the chances that it was originally legit. :happysad:

250.32(B).

 

[kwired]

Main breaker in the garage? Is garage a separate structure?

If yes to both then there could be a 100 amp at the supply end and a 60 at the garage end making the supply circuit an outside feeder tap of unlimited length.

If not a separate structure there is no question, there should have been a separate EGC, could possibly still use a feeder tap but depends on more details, and a GEC wouldn't be needed.