Temporary Generator Grounding

[steve66]

The electricians will be using a temporary generator (mounted on a trailer outside the building) to supply a MCC while some work is done on the MCC's normal feed.

The MCC is a 3 wire MCC (no neutral) so they won't run a neutral wire from the generator to the MCC.

So the question of grounding came up. Specifically, do we need to run a ground wire from the generator to the MCC? And, do we need a grounding electrode at the generator?

I think the answer is yes to the ground wire, and yes to the electrode.
But I wanted to ask what all the experts here think. Are they required??

 

[chris kennedy]

Generators don't produce an equipment ground. Read generator specs, most I see require some kind of GE.

 

[iwire]

We would run an EGC from genset to MCCC in order to operate the OCPD in the genset if there was a line to ground fault on the feeder.

We also run a GEC from the Genset to building steel, it is redundant but very easy and makes sure everything is staying close to the same potential.

 

[chris kennedy]

We would run an EGC from genset to MCCC in order to operate the OCPD in the genset if there was a line to ground fault on the feeder.

And connect it to what at the genset? In a non SDS that grounded bus will float. OP states 3? 3 wire, so that would make this set-up by default a SDS, correct?

We also run a GEC from the Genset to building steel, it is redundant but very easy and makes sure everything is staying close to the same potential.

Also probably in the genny install instructions.

 

[steve66]

The second ground wire sounds like a good idea.

So a ground rod at the generator isn't required??

 

[76nemo]

250.34 (A) (1)........(2005) Sorry:roll:

 

[iwire]

We would run an EGC from genset to MCCC in order to operate the OCPD in the genset if there was a line to ground fault on the feeder.

And connect it to what at the genset?

The EGC terminal located beside XO, X1, X2, X3.

The second ground wire sounds like a good idea.

So a ground rod at the generator isn't required??

An electrode is often required but a rod is a pain so as long as we have building steel that qualifies as an electrode we will use it.

 

[steve66]

An electrode is often required but a rod is a pain so as long as we have building steel that qualifies as an electrode we will use it.

Now I get it. Thanks Bob and all.

Steve