What size equipment grounding conductor?

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fbhwt

Electrical Systems Inspector
Location
Spotsylvania,Virginia
Occupation
Electrical Systems Inspector
I am in dispute over the size equipment grounding conductor needed. Service is 1000a ,208v, 3ph
3 sets of 4-400mcm from 1000a service disconnect to 1000a transfer switch. I say it should be 2/0 copper or 4/0 alu according to 250.122, disconnect is fused at 1000a
 

ibew441dc

Senior Member
I am in dispute over the size equipment grounding conductor needed. Service is 1000a ,208v, 3ph
3 sets of 4-400mcm from 1000a service disconnect to 1000a transfer switch. I say it should be 2/0 copper or 4/0 alu according to 250.122, disconnect is fused at 1000a

It sounds like you got it down.....but just remember the EGC has to be full size in each of the raceways in parallel.
 

fbhwt

Electrical Systems Inspector
Location
Spotsylvania,Virginia
Occupation
Electrical Systems Inspector
I was told I was not looking in the right place, something about 250.66, which we know is for sizing grounding electrode conductor.
 

ibew441dc

Senior Member
I was told I was not looking in the right place, something about 250.66, which we know is for sizing grounding electrode conductor.


The short answer for you to back your self up(because you are correct) is to take a look at 250.102(C) and (d)
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Once you are beyond the service disconnecting means, table 250.66 is no longer a player. I agree with the others: you had it right.
 
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