portable 3 phase generator grounding

[mrmike]

if you have a 3 phase Generator on wheels feeding a 3 phase load on wheels will there be a difference in ground potential between the size of them? Should there be an earth ground rod installed? Where would the neutral wire which is center tapped from the generator be hooked up load side even if know Neutral is needed for the load??? The neutral & ground are jumpered at the output of the Generator...........

 

[Smart $]

if you have a 3 phase Generator on wheels feeding a 3 phase load on wheels will there be a difference in ground potential between the size of them?

I don't understand "between the size of them".

The EGC should keep all non-current-carrying metal parts at the same potential to both earth and energized parts and conductors, provided there are no faults and all are properly bonded.

Should there be an earth ground rod installed?

Not required, and also not prohibited.

Where would the neutral wire which is center tapped from the generator be hooked up load side even if know Neutral is needed for the load???

The neutral would not be connected to anything if the load does not require one.

 

[LarryFine]

The neutral would not be connected to anything if the load does not require one.

But, the generator grounding conductor should be connected to the building grounding conductor.

 

[Smart $]

But, the generator grounding conductor should be connected to the building grounding conductor.

What building???

 

[LarryFine]

What building???

Excuse me. (The building in my mind. :roll The generator and the two chassis' grounds should be bonded.

The generator's neutral terminal should remain bonded to that ground, too, and it wouldn't hurt to drive and bond to a rod.

 

[hurk27]

and it wouldn't hurt to drive and bond to a rod.

as long as you don't hit your hand in doing so

I just can't see a purpose for the ground rod? :-?
Isolation from Earth is one of the safest installs you could ask for in a very local system?

 

[mrmike]

Wrote here this morning & now its gone............ I hate updating-- Anyhow, I am just as confused by the replies on this one. Do you hook the neutral to ground on the load if neutral isn't used?? It makes sense to me to have each chassis grounds bonded together but I am not sure about a ground rod since these mobile generators will be moved quite often................... Thanks for your input & please give more............ So I can learn more on this...................

 

[dereckbc]

as long as you don't hit your hand in doing so

I just can't see a purpose for the ground rod? :-?
Isolation from Earth is one of the safest installs you could ask for in a very local system?

Niehter do I as it serves no purpose in this application. Well unless you are on a bare mountaintop under a t-storm it might serve a purpose.

 

[dereckbc]

N-G bond is done at the generator. If no single phase loads are required, you do not need to carry the neutral to the load, fault returned via EGC back to Generator N-G bond. No ground rod required or needed in this application.

 

[steve66]

No ground rod required or needed in this application.

I'm not sure I agree. I think you should refer to the manufacturers instructions for both the generator and the load and see what they say about ground rods.

I agree that isolation from ground can be safe, but I don't see any way to gurantee that this is isolated. Especially since we don't know what the load is.

 

[mrmike]

The load is a snowmaker- which we are feeding with a Baldor 3 phase generator, and is being moved to different spots to distribute the snow. Using a 50' cord between them...
The Gen book does say to drive a ground rod............ thus the concern........

 

[Smart $]

The load is a snowmaker- which we are feeding with a Baldor 3 phase generator, and is being moved to different spots to distribute the snow. Using a 50' cord between them...
The Gen book does say to drive a ground rod............ thus the concern........

Thus installing a ground rod is indirectly required per 110.3(B).

Does the instructions cite any conditions of use for which to drive a ground rod?

Does it specify where to make connection?

Must we assume it is to be connected, even if the instructions do not specifically say to make a connection??? ...

 

[rh0411]

3-phase vehicle mounted generator grounding

3-phase vehicle mounted generator grounding

I'm not sure I agree. I think you should refer to the manufacturers instructions for both the generator and the load and see what they say about ground rods.

I agree that isolation from ground can be safe, but I don't see any way to gurantee that this is isolated. Especially since we don't know what the load is.

I have a similar situation. A trailer mounted generator feeds another trailer with 480V, 3-phase 3-wire plus equipment ground. All loads are either on the trailer or cord-and-plug-connected. The trailer includes the starters and controls for cord-connected submersible pumps and other cord-connected loads. All cords and receptacles contain an equipment ground that is also connected to the generator frame. No transfer switch or fixed building loads are involved. Given that the pump cases are connected to equipment ground, there is no isolation from earth. Is a generator frame connection to a site ground electrode encouraged or discouraged in this case? Thanks for any input!