Calculate EGC

[boku0003]

Two 500 kcmils are paralleled. What size copper equipment grounding conductor is needed?

You size the EGC based on the OCPD, which is not given. So I took the 500 kcmil current rating (based on the 75C column) and multiplied by 2 (since they were paralleled). 380x2=760A. This would require an 800 amp OCPD. In 250.122, this equates to a copper EGC of 1/0.

Or do you use the current of 1000 kcmil, which is 545 which would give you a 600 amp OCPD and a 1 AWG EGC?

I believe it's the first one...

 

[infinity]

Two 500 kcmils are paralleled. What size copper equipment grounding conductor is needed?

You size the EGC based on the OCPD, which is not given. So I took the 500 kcmil current rating (based on the 75C column) and multiplied by 2 (since they were paralleled). 380x2=760A. This would require an 800 amp OCPD. In 250.122, this equates to a copper EGC of 1/0.

I would use this method. #1/0 in each raceway.

 

[Dexter C]

Yes, 1/0 AWG is the correct answer according by 250.122.

 

[ggonza]

1/0 is good, but 800 A isn't required. It's allowed

 

[SG-1]

Or do you use the current of 1000 kcmil, which is 545 which would give you a 600 amp OCPD and a 1 AWG EGC?
QUOTE]

Circular mil based increase in size is used when the conductor is upsized for volt drop or other any other reasons. 250.122(B).

Another thing to keep in mind is that the chart given in 250.122 is minimum size.

I agree with Dexter C & Infinity.
When you do not know you error on the side of safety. The 1/0 works in both cases.