Building used to just house Array, is a grounding electrode required at the building?

[ryangittens]

I have a system that is going to be installed at a building but connected to transformer 300ft away. The building has its own service, but the array is connected directly to the grid through a transformer 300ft away. The building is basically just being used to house the array.

Is there an additional electrode required at the disconnect located at the building in addition to the one at the service disconnect at the transformer? Or does it need some connection to the existing GE at the building?

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[zbang]

I'm curious whether this would run into 230.2 (more than one service to a building) unless it also complies with 230.2(A)(5) Parallel power production systems. (Add in the "Is this a branch circuit or a feeder?" discussion.)

I'd assume that the EGC run from the far building needs bonding to the existing GEC at the support building but can't see anything in 690.47 suggesting you'd need an additional electrode.

 

[jaggedben]

Interesting question.

In both the 2014 NEC and 2017 NEC you need an electrode system at the structure where the array is. In 2014 (690.47)(D) you're supposed to provide an array electrode; it's a stupid requirement but the AHJ may require you to put in a new electrode to meet it. On the other hand, 250 requires that all electrodes at a structure be tied together, so that argues for grounding to the existing GES instead of installing a new one. That argument is stronger under the 2017 code.

As far as the issue of multiple services connecting to the same building, I think you can justify that under 230.2(D) 'different uses'. As long as you have appropriate signage.

 

[ryangittens]

Awesome. We're still on the 2011 NEC so I'll go ahead and leave it off. And I agree that the additional electrode requirement is stupid.

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