grounding requirements for generator install

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Starbuc

Starbuc
Location
Lake City, FL
Occupation
Master Electrician
I am in the process of installing a 100kw back-up generator, the service is three/phase, 4-wire, all conductors are 500mcm copper. the transfer switch is a 3-pole, with isolated lugs for nuetral, I am planing on using a 400a nema3 breaker ahead of the transfer switch. Does anyone know what needs to be done for grounding?
 
Re: grounding requirements for generator install

Lyn,
With the information you have given the generator would not be considered a separately derived system. Therefore, running a properly sized equipment grounding conductor(NEC 250.122 = #2 copper for 500mcm) from the service equipment, then to the transfer switch, and then to the generator would suffice. You must also be sure to remove any factory installed boning jumper between your neutral and ground connections on the generator.

I hope this helps,
Jerimi Meyers
Electrical Inspector
 
Re: grounding requirements for generator install

Jerimi,
Thanks for the reply, is it acceptable to run a single grounding conductor (#2 copper thhn) through a building (above the ceiling) without putting it in conduit?
 
Re: grounding requirements for generator install

You must also be sure to remove any factory installed boning jumper between your neutral and ground connections on the generator.
Click to expand...
Make sure that the manufacture permits this.

Also, some manufactures require a ground rod(s) at the generator location.
 
Re: grounding requirements for generator install

Lyn,
The equipment grounding conductor must be run with the generator conductors.
Don
 
Re: grounding requirements for generator install

Second Don's comment. EGC's will have to run with the conductors just like any feeder.
 
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