grounding of pv frame

[Hendrix]

Are ground rods or other grounding systems required for the frame that the array is on?

 

[jtopham26]

you shouldn't need an additional one if your service is grounded

 

[Hendrix]

That's what I thought, but state inspector says you do:huh:

 

[ggunn]

That's what I thought, but state inspector says you do:huh:

IIRC the NEC allows but does not require an auxiliary rod at the array.

 

[GoldDigger]

IIRC the NEC allows but does not require an auxiliary rod at the array.

That changed in [2014].

 

[Carultch]

That changed in [2014].

According to this video, it is counterproductive to safety to add it:
https://www.youtube.com/watch?v=YuDqXFvRv94

 

[cuba_pete]

more

more

There is a lot more that should go into the question. Is it roof mounted? Is it in a field? What are the manufacturer's "auxiliary electrode" requirements? etc.

NFPA 70 and 780 come to mind.

Keep voltage gradients in mind.

AHJ rules.:thumbsup:

 

[ggunn]

That changed in [2014].

Thanks. Can you direct me to the code that changed?

 

[GoldDigger]

Thanks. Can you direct me to the code that changed?

690.47(D) was added.
Other parts may have been renumbered, so direct comparison may not be easy.
The particular problem that Mike Holt is objecting to most strongly is that as an auxiliary electrode, there is no requirement to connect it by GEC or bond to the rest of the GES. That can cause major potential differences and undesirable current in the system in the case of nearby lightning strikes.

 

[ggunn]

690.47(D) was added.
Other parts may have been renumbered, so direct comparison may not be easy.
The particular problem that Mike Holt is objecting to most strongly is that as an auxiliary electrode, there is no requirement to connect it by GEC or bond to the rest of the GES. That can cause major potential differences and undesirable current in the system in the case of nearby lightning strikes.

Thanks. I have in the past sometimes included auxiliary rods in my designs, but I have always bonded them back to the primary GES of the facility.

 

[Hendrix]

The State inspector wants two ground rods coming directly from the frames, on roofs as well as on ground arrays. Or he said you can go to the street side of the city water.

 

[GoldDigger]

The State inspector wants two ground rods coming directly from the frames, on roofs as well as on ground arrays. Or he said you can go to the street side of the city water.

That is either a local amendment or a shirt pocket rule.

 

[jaggedben]

There is a lot more that should go into the question. Is it roof mounted? Is it in a field? What are the manufacturer's "auxiliary electrode" requirements? etc.

Fwiw I have never ever seen any pv module instructions say a word about the type of grounding electrode. At most they cover the method of bonding the frame and when it comes to wire size and where it goes they say "consult your local code", if they say anything at all.

That is either a local amendment or a shirt pocket rule.

What's the etymology of 'shirt pocket rule'?

 

[GoldDigger]

When asked what code section was violated, the inspector pulls a card out of his pocket with the rule handwritten on it?

 

[bnwitt]

690.47(D)

690.47(D)

This really needs to be clarified by the code writers. If Mike Holt is correct, every installation where the contractor is forced to add an auxiliary grounding electrode as per 690.47(D) is spending additional money and making the system less safe. We don't need ignorance driving design like this. I would really like to hear from anyone involved or who knows someone involved with writing the next code cycle as to where this is going.

Barry