ECN Forum Forums Code Related Discussion NEC & other Code issues Grounding Generators

Most generators I've seen have an integral circuit breaker. I'll give the following example. A 50KW 120/208V. 3 phase 4/W. The generator would be the only power source to feed a panelboard 50 feet away that will be used in a Park setting for a special event. I would ground and bond at the generator and isolate the neutral in the "remote" panelboard. My feeder assembly would consist of (three) phase conductors, a neutral conductor and an equipment grounding conductor. Does anybody disagree with this installation?

Frank (cinkerf)

So, the generators main would be the main disco, within sight? the panelboard in MLO??



[This message has been edited by sparky (edited 04-19-2001).]

Sparky,

I would probably have a main disconnect in the remote panelboard. Grounding is the real point of my question. If the generator has a main circuit breaker then anything downstream of it should be treated as a feeder. At least that is my understanding. I'm just interested in how other people around the country view this and how they ground such an installation.

Frank (cinkerf)

Frank,

Sounds good to me.


Bill

At the risk of having my opinion rammed down my throat. I will state: you don't need the EGC if you use a non-metallic jacketed multi-conductor cable from the generator to the remote panel and there are no continuous metallic paths (e.g., metal conduit/flex) bonded to the grounding system at the generator and panelboard (no parallel path back to the generator).
You ensure the generator frame is bonded to its grounded conductor. Drive a ground rod near the generator and connect the GEC to the generator's grounded conductor.
Treat the remote panel as a service panel.
Bond the panelboard and EGC buss to the neutral. Drive a ground rod and install a GEC
connected to the neutral in the panelboard.
Or you could do it just the way you described it. Thanks

Mike,

I have seen it done that way. I guess that is why I raised the question in the first place. I wasn't aware that both were acceptable methods. The integral generator circuit breaker is what made me post the question.

Frank (cinkerf)

Mike;
i'm not going to disagree, as either method could be NEC justified.
But i would like to have some fun with it!

what say we do it that way, and the genny's only 20' away.....real low impedance soil.....somebody must have had a garden or chickenhouse there at one time......

Sparky,

Sounds like a good place to open a Bait Stand!


Bill

Good question, Sparky! Are you suggesting the possibility of a parallel path with the ground rods 20 feet apart? The NEC states that a ground rod must have a 25 ohm or less impedance. A second ground rod is required if the first one is more than 25 ohms. Also, the GEC/rod and grounded conductor are the same potential. And the grounded conductor has the least resistance.

Mike;
well yes, and apparently code compliant too, jsut fishin' for opinion, beats cuttin' bait!