Plan Review, EGC Size

[bob]

Check the first post by infinity. He just had a question regarding the EGC.

 

[infinity]

You stated a # 12 ground. Are they for sure talking about the grounding conductor or is it a grounded conductor.
Just curious. As some have already stated that the emt could possibly be used for the equipment ground.
If it is a grounded conductor it is possible that it could be sized smaller based on the unbalanced load. Do not know what the circuit is being used for?

Yes, this is about the EGC. The engineer chose the word ground instead of EGC, not me.

 

[Larry the cable guy]

Voltage drop?

 

[bob]

That is what the code requires but the question is why. If the #12 gnd is good for the #12 ckt, why is it not good if the conductor is changed to #10? The gnd is supposed to have low enough impedance to ensure the breaker trip when a fault occurs. That has not changed.

Can anyone answer this question?

 

[Smart $]

Can anyone answer this question?

I can only speculate...

Say you increased size to #10 for voltage drop reasons. The voltage drop is caused by the conductors self-heating, increasing the impedance. The longer #10 now has an equivalent impedance to a shorter #12. With the EGC in close proximity, the heat generated by the circuit conductors is transmitted thereto, increasing its impedance. So we now have a #10 EGC with an equivalent impedance to a shorter #12.