Genset Breaker to Switchgear Grounding

[dcreaney]

Greetings,

I have a genset enclosure that has a 2500KW generator with a 4000A breaker that feeds a 4000A switchgear inside the enclosure. I am running (10) 444KCMIL DLO cables per phase and neutral and (2) 444KCMIL DLO cables per ground. The cable is routed from the genset to the switchgear in 2 layers of cable tray, (2) 444KCMIL DLO per tray. I have always sized the ground per NEC 250.66 grounding electrode conductor. I have an inspector that is saying these grounds need to be sized per NEC 250.122 (F) (1) equipment grounding conductors. So, I am curious which code would apply to this application.

 

[d0nut]

If you use the correct terminology, you will know which table to use. Where does each end of the "ground" wire in question terminate?

 

[zbang]

Pet peeve here-
Are you using actual DLO (not an NEC cable type) or are you using a fine-stranded dual-listed cable that's also RHH/RHW-2? (Or why not just use THHN can be done with it? Or another NEC fine-strand type like W? If you don't need the 2kv insulation you're wasting money on it.)

 

[ron]

The generator feeder downstream of the n-g bond is a feeder not a service or supply side bonding jumper so it would be an equipment grounding conductor 25.122

 

[dcreaney]

If you use the correct terminology, you will know which table to use. Where does each end of the "ground" wire in question terminate?

One end at the generator and one at the switchboard.

 

[dcreaney]

Pet peeve here-
Are you using actual DLO (not an NEC cable type) or are you using a fine-stranded dual-listed cable that's also RHH/RHW-2? (Or why not just use THHN can be done with it? Or another NEC fine-strand type like W? If you don't need the 2kv insulation you're wasting money on it.)

Using a UL listed RHH/RHW that is also TC rated.

 

[zbang]

OK, so you're not using DLO, you're using RHH/RHW. I'm still curios why you're using that and not some other cable.

One end at the generator and one at the switchboard.

Where are those terminating- on a ground bus at each end or ???? (Where is the N/G bond of the system? Is there on at the generator or is it in the switchboard? Another way to look at this- is the generator a Separately Derived System or not?)

 

[dcreaney]

OK, so you're not using DLO, you're using RHH/RHW. I'm still curios why you're using that and not some other cable.


Where are those terminating- on a ground bus at each end or ???? (Where is the N/G bond of the system? Is there on at the generator or is it in the switchboard? Another way to look at this- is the generator a Separately Derived System or not?)

That is the type of cable that the customer has specified for the job.

They both terminate at bus bar and the N/G bond is at the genset.