Shared Ground conductor

[thewire]

So, I have a question.

If I have 2 branch circuit that will be installed within the same duct run. Both circuits are on 20A breaker. I will have 3 #12 cables and 1 #12 ground. It will be sharing neutral as well.

Should I up the ground conductor be up the size to #10 according to tabl 250.122?

 

[augie47]

As long as your overcurrrent devices are 20 amp and your wire is #12, I see nothing in 250.122 that would require an up-sized equipment grounding conductor.;
You would need to comply with the provisions of 210.4

 

[raider1]

I agree with Augie47. In fact if you look closer at 250.122(A) it specifically states that in no case shall the equipment grounding conductor be required to be larger than the circuit conductors supplying the equipment.

Chris

 

[thewire]

As long as your overcurrrent devices are 20 amp and your wire is #12, I see nothing in 250.122 that would require an up-sized equipment grounding conductor.;
You would need to comply with the provisions of 210.4

I think the 210.4 should be ok since both of the branch circuits are on separate circuit breaker.

The reason i mentioned 250.12, i am confused because the Overcurrent device for both circuits with a ground fault might exceed the #12 (20A)

 

[raider1]

I think the 210.4 should be ok since both of the branch circuits are on separate circuit breaker.

What Augie was pointing out with his reference to 210.4 if that if you are sharing a neutral you have a multiwire branch circuit by definition and that 210.4 would require either a 2 pole common trip breaker or 2 individual breaker equipped with a common handle tie.

The reason i mentioned 250.12, i am confused because the Overcurrent device for both circuits with a ground fault might exceed the #12 (20A)

The #12 EGC would be sufficient to carry the fault current to clear both 20 amp breakers during a ground fault that may occur with both circuits at the same time.

Chris

 

[augie47]

In addition, an this is supposition on my part, I think the CMP has taken into account the possibility of both phase conductors have a simultaneous bolted fault to ground is rare.