Neutral to first disconnect question

[paul]

Situation is we are temp feeding some service gear with a temp generator skid. 480/277. Grounded conductors in the system stop at this gear, first disconnect. We are feeding with DLO 4/0 cables. 8 per phase. 2 for grounding conductors.

Originally I was told no grounded conductor, but when I got there I realized it was the first disconnect and I need to bring my neut and land it. I am planning on bringing only 1 (4/0) to bond.

My question is do I need to match my 2 grounding conductors and bring 2 neutrals over or can I get away with 1? Inspection later this afternoon. Mind you this will all be taken apart and put back together in the original configuration around 3am tomorrow morning.

Thanks.

Edit to add, there is NO load on the grounded conductor.

 

[Dennis Alwon]

Technically the neutral cannot be smaller than the equipment grounding conductor. I am not sure of the load setup but IMO you need to run the neutral

 

[augie47]

Loy of varibles, Is the neutral bonded at the generrator, are the conductors in concuit.
Either way, I would not be suprised if the AHJ allowed you to pass since it's a "temporary" situation.

 

[infinity]

If you're one the line side of a service disconnect you need grounded conductors not grounding. The minimum size is found in T250.66. Take a look at 250.24(C).

 

[david luchini]

I don't see any reason to bring a grounded conductor from the temp. generator to the disconnecting means, if it is not being used as a circuit conductor.

 

[jim dungar]

Be clear in your terminology.

Is this a service entrance supplied by a POCO? If yes, you need to bring in a grounded conductor and N-G bond in the gear.

Is this a separately derived system? Does your first disconnect have a removable N-G bond? If yes, you can bond at the source and bring in a grounding conductor.

 

[Smart $]

Situation is we are temp feeding some service gear with a temp generator skid. 480/277. Grounded conductors in the system stop at this gear, first disconnect. We are feeding with DLO 4/0 cables. 8 per phase. 2 for grounding conductors.

Originally I was told no grounded conductor, but when I got there I realized it was the first disconnect and I need to bring my neut and land it. I am planning on bringing only 1 (4/0) to bond.

My question is do I need to match my 2 grounding conductors and bring 2 neutrals over or can I get away with 1? Inspection later this afternoon. Mind you this will all be taken apart and put back together in the original configuration around 3am tomorrow morning.

Thanks.

Edit to add, there is NO load on the grounded conductor.

Since you said service gear, and first disconnect, I'll assume the service conductors are going to be disconnected and isolated/insulated.

The requirement to bring the grounded conductor to the gear only applies to services. In this temporary configuration, the gear will not be a service... so no grounded conductor need be run. Because it is not an ungrounded system, the gennie's system does have to be grounded. Assuming there is ocpd integral with the gennie, that will be the first disconnect in the temporary separately derived system. You will have to run GEC's (sized per 250.66) to the gennie, bond neutral to GEC's and enclosure at the gennie (probaly have to drive and connect a ground rod too). You do not have to disconnect neutral bus to GEC/grounding system at the gear as long as there are no load connections and the service neutral is disconnected and isolated.