Ground Size

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jaykool

Member
Location
NE
The prints call for 4 sets of 3/C 500kcmil with a #4/0Gnd to feed a 1600A MCC.

Talking with cable manufacturers, #2 gnd cable is standard and #4/0 is a special order. Can I specify #2 gnd and still be compliant with code?
 

drbond24

Senior Member
I'm curious why you were considering deviating from the print to begin with. If the prints say you need purple insulation on all the cable, that is what you need. If you wanted to change that you would need the permission of the person who made the print, not us.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
What size is the OCPD on the supply end of the 4 sets of 500kcmil? 1600 would not be permitted by the code rules.
 

drbond24

Senior Member
The prints call for 4 sets of 3/C 500kcmil with a #4/0Gnd to feed a 1600A MCC.

Talking with cable manufacturers, #2 gnd cable is standard and #4/0 is a special order. Can I specify #2 gnd and still be compliant with code?

I was just thinking about this and realized why the prints called for #4/0. You are correct in that #2 AWG would be the 'regular' grounding conductor for a 350 MCM cable. However, #4/0 AWG is the size of the equipment grounding conductor for an overcurrent device rated 1600 A.

I'm a little slow today, so this is probably why the others said you couldn't change the wire size in the first place. :) I just caught on myself.
 

jaykool

Member
Location
NE
MCC is being fed with a 1600A breaker, dialed down .95...1520A.

500kcmil good for 380A (the one I am going to purchase)...380x4=1520A.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
MCC is being fed with a 1600A breaker, dialed down .95...1520A.

500kcmil good for 380A (the one I am going to purchase)...380x4=1520A.
In that case the EGC only needs to be 3/0 per the code. That is assuming the breaker complies with the rules in 240.6(C).

Note:The first part of my post is in error. See the below.
 
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