When Are Ground Rods Required at a Generator?

[jar546]

I've only seen a handful of installations that required this. As a matter of fact, I can probably count them on one hand. There are situations where ground rods are required at a generator. Who knows the answer as to under what circumstances ground rods are required at a generator?

 

[Mr. Inspector]

When the plans require them.

 

[jar546]

When the plans require them.

That is not the answer we are looking for. We are looking for an NEC-driven answer that not only changes the ground rod requirements, but how the system is wired and disconnected.

 

[steveray]

When it is a separately derived system

 

[wwhitney]

When it is a separately derived system

Does not require ground rods at the generator, merely requires a GEC (Grounding Electrode Conductor) to a GES (Grounding Electrode System). The adjacent building's GES could be used. In fact if the generator is sufficiently close to the structure, any ground rods you install for it must be connected back to the building's GES.

The only requirement I can see for a ground rod at the generator itself would be 110.3(B), if the listing standard requires one. Of course, until the 2020 NEC generators weren't required to be listed.

Cheers, Wayne

 

[steveray]

Does not require ground rods at the generator, merely requires a GEC (Grounding Electrode Conductor) to a GES (Grounding Electrode System). The adjacent building's GES could be used. In fact if the generator is sufficiently close to the structure, any ground rods you install for it must be connected back to the building's GES.

The only requirement I can see for a ground rod at the generator itself would be 110.3(B), if the listing standard requires one. Of course, until the 2020 NEC generators weren't required to be listed.

Cheers, Wayne

And what is that sufficiently close dimension in the NEC again?....Yes, they could use some other grounding electrode, such as rebar in the concrete supports, but my point was that it did not need it's own GES unless it was an SDS....But even that answer could be a little fluid...