Equipment grounding conductors

[wangyumei]

I have a project with 175amp load at 240V, single phase. Due to the distances from the service transformer to the service panel, the feeder conductors are sized as 3 sets of (3-#4/0 AWG, plus ground). Per NEC section 250.122.B, the equipment grounding conductor in each set needs to be increased proportionnately per the phase conductors. So the grounding conductors will be #1/0. It is a pretty big grounding conductor. My question is that since this grounding increase is due to voltage drop, is there any exception in NEC for a smaller grounding conductor in this situation?

 

[Dennis Alwon]

The main reason IMO for upsizing the equipment grounding conductor when increasing the conductor sizing is for voltage drop. I believe at one time the NEC stated it that way. The issue with long distance is that the equipment grounding conductor will have too great an impendance and thus needs to be upsized to ensure the breaker with trip on a fault.

There is no exception

 

[iwire]

I agree with Dennis.

There is some controversy about the need for this but regardless the NEC requires it.

On the other hand if this circuit is run in a metal conduit or tubing you could leave the wire EGC at the supply house.

 

[wangyumei]

Thanks a lot. Just wanted to see if there are exceptions.