EGC & Voltage Drop

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Npstewart

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After figuring the voltage drop for a particular circuit, if the conductors are required to be upsized, is the EGC ALWAYS required to be up sized?

I know the EGC is based off of the rating of the OCPD and not the area as in 250.66, so how would you know which size to go with? Would it be wise to match the EGC with the new upsized feeder?

Thanks!
 
LarryFine

LarryFine

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Npstewart said:
After figuring the voltage drop for a particular circuit, if the conductors are required to be upsized, is the EGC ALWAYS required to be up sized?
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Always.

Reasoning: someone could later decide to use the larger conductor at its ampacity.

I know the EGC is based off of the rating of the OCPD and not the area as in 250.66, so how would you know which size to go with?
Click to expand...
Proportionately, in area, to the conductor size increase.
 
jumper

jumper

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250.122(B) Increased in Size. Where ungrounded conductors are
increased in size, equipment grounding conductors, where
installed, shall be increased in size proportionately according
to the circular mil area of the ungrounded conductors.
 
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Npstewart

Senior Member
The issue I have is that the NEC doesen't really give a relationship between the size of the EGC and the size of the ungrounded conductor because the size of the EGC is based off of a device rating. I suppose I know how to do it, it just isn't clear at all.
 
infinity

infinity

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Although this section is poorly constructed the general idea would be to start with the minimum conductor size and work up from there. For example if you had a 20 amp circuit you would start with a #12 ungrounded conductor and a #12 EGC from table 250.122. If you went up to #10 ungrounded conductor your EGC would increase to #10 also. The confusion here is what's the actual starting point. In this example it's rather simple, 20 amp circuit #12 ungrounded conductor, #12 EGC. In many instances the simplicity of where to start does not exist.
 
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