Grounding question

[ggunn]

We are building three PV systems at a facility that has several buildings and several meters. The customer wants two of these systems to be on the same building (a parking garage), one feeding the meter at the garage and the other feeding the meter on an adjacent building. The PV modules are to be mounted on steel canopies, and the plan is to have part of one system and part of the other on the same canopy, which would put the ECG's of the two systems in electrical contact with each other through the structural steel. Is this a problem?

 

[jaggedben]

I don't believe it's a problem. Ground is ground. I suppose there might be potential for a ground loop that could adversely affect other systems (e.g. communications), but I don't believe it's a code issue.

 

[ggunn]

I don't believe it's a problem. Ground is ground. I suppose there might be potential for a ground loop that could adversely affect other systems (e.g. communications), but I don't believe it's a code issue.

Thanks. In a former job I was designing a couple of systems where this came up as a problem, but it was in California and was likely a local issue.

 

[Dennis Alwon]

Think of it like this-- if there were a city water system that was metallic wouldn't you be connected to everyhouse of the system thru the grounding electrode conductor to the pipe? This in turn is connected to the equipment grounding conductor's also

 

[jaggedben]

Thanks. In a former job I was designing a couple of systems where this came up as a problem, but it was in California and was likely a local issue.

I work in one jurisdiction where they have a local amendment to article 300 that prohibits wiring connected to different meters from being in the same raceway. Some thing like that would require the circuits for the two PV systems to be kept separate and have separate EGCs. But an EGC connection to structural steel is still very incidental to that and still would not be a problem in that case.

 

[ggunn]

I work in one jurisdiction where they have a local amendment to article 300 that prohibits wiring connected to different meters from being in the same raceway. Some thing like that would require the circuits for the two PV systems to be kept separate and have separate EGCs. But an EGC connection to structural steel is still very incidental to that and still would not be a problem in that case.

Be that as it may, for the system I mentioned in California the AHJ made us break up the steel between the two arrays so that the EGC's for the two systems did not touch. I didn't think it was a NEC requirement, but I wanted to be sure.

And yes, I know that there is only One True Ground.