Grounding and Bonding

[C.Goodrich]

I have a question about grounding and bonding for a Solar install on residential. House is 200A Meter on the exterior and then enters the house where the main panel and main breaker are. A line side tap was performed inside the main panel, then went outside to the PV AC disconnect. That disconnect had ground rods installed and a grounding bar installed. A ground wire was ran from the PV disconnect to the main panel. All conduit was bonded via bond bushings. The utility failed us for this and said we need to remove the wire from the PV disconnect to the main panel. Can anyone explain if this is an actual code violation? I cannot find anywhere that says we are not up to code. When I looked, I found the opposite. We operate out of the 2017 NEC. Article 250.30(A)(4) and 250.58 both say that for a separately derived system or service, the same grounding electrode system shall be used. So isn't removing that ground wire against code? Thanks in advance.

 

[ggunn]

I have a question about grounding and bonding for a Solar install on residential. House is 200A Meter on the exterior and then enters the house where the main panel and main breaker are. A line side tap was performed inside the main panel, then went outside to the PV AC disconnect. That disconnect had ground rods installed and a grounding bar installed. A ground wire was ran from the PV disconnect to the main panel. All conduit was bonded via bond bushings. The utility failed us for this and said we need to remove the wire from the PV disconnect to the main panel. Can anyone explain if this is an actual code violation? I cannot find anywhere that says we are not up to code. When I looked, I found the opposite. We operate out of the 2017 NEC. Article 250.30(A)(4) and 250.58 both say that for a separately derived system or service, the same grounding electrode system shall be used. So isn't removing that ground wire against code? Thanks in advance.

I think I understand what you are asking. Under the 2017 NEC for a supply side interconnection some jurisdictions want you to bond neutral to ground in the PV AC disco and run a GEC externally from the disco to the building ground rod instead of an EGC through the conduit. The NEC is murky so you'll just need to do what the inspector says because you won't find anything in it that explicitly says one way or the other.

 

[jaggedben]

The utility is being stupid and possibly dangerous if that's all they told you. Right now you have a wire bonding the PV disconnect to (ultimately) the service neutral in the main panel. If you remove that wire then what is bonding the disconnect? Maybe the conduit, but the ground wire certainly isn't hurting anything. (The ground rods do basically nothing and were unnecessary unless the house didn't already have compliant grounding, or unless a stupid AHJ is requiring them for no good reason.)

I would ask them how they want you to bond the PV disconnect. Or if you don't want to wait for that answer, replace the green wire with a white one (this is the same as what ggunn calls bonding neutral to ground in the disconnect) and call for reinspection. BTW this is what the 2020 NEC would require in 250.25, but ggunn is correct that 2017 is unclear.

 

[C.Goodrich]

So I'm looking at more pictures (I didn't do the install, one of our build partners did). The line side tap included a neutral tap as well. So the PV disconnect does have a neutral wire in there for bonding. It is wired up like a main panel. Bonding screw inserted, neutral and grounding electrode wire on neutral/grounding bar.

 

[pv_n00b]

As ggunn wrote, the 2017 NEC is murky. It allows either the ground-neutral bond in the PV disconnect or the use of the one already in the main service panel. The 2020 NEC made it explicit that the way you did it is the way to do it. Although I think there are some people around who don't think it was fixed in 2020.

 

[jaggedben]

So I'm looking at more pictures (I didn't do the install, one of our build partners did). The line side tap included a neutral tap as well. So the PV disconnect does have a neutral wire in there for bonding. It is wired up like a main panel. Bonding screw inserted, neutral and grounding electrode wire on neutral/grounding bar.

Then you can remove the green wire that's redundant woth the neutral. I suppose they think it might carry objectionable current.