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Grounding Generators #77050 04/19/01 04:54 PM
Joined: Dec 2000
Posts: 84
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cinkerf Offline OP
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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)

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Re: Grounding Generators #77051 04/19/01 05:04 PM
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sparky Offline
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So, the generators main would be the main disco, within sight? the panelboard in MLO??

[Linked Image]

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

Re: Grounding Generators #77052 04/19/01 05:17 PM
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cinkerf Offline OP
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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)

Re: Grounding Generators #77053 04/19/01 05:47 PM
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Bill Addiss Offline
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Frank,

Sounds good to me.

[Linked Image]
Bill


Bill
Re: Grounding Generators #77054 04/19/01 05:56 PM
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Mike Offline
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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

Re: Grounding Generators #77055 04/19/01 06:11 PM
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cinkerf Offline OP
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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)

Re: Grounding Generators #77056 04/19/01 09:57 PM
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sparky Offline
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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......

[Linked Image]

Re: Grounding Generators #77057 04/19/01 10:17 PM
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Bill Addiss Offline
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Sparky,

Sounds like a good place to open a Bait Stand!

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Bill


Bill
Re: Grounding Generators #77058 04/20/01 02:18 PM
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Mike Offline
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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.

Re: Grounding Generators #77059 04/20/01 08:25 PM
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sparky Offline
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Mike;
well yes, and apparently code compliant too, jsut fishin' for opinion, beats cuttin' bait!

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