Ground wire size...


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Old 05-12-09, 07:39 AM
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Ground wire size...

I have a question for the ground to the load center.

Lets just say, hypothetically, you are using #6 wiring to a subpanel, should the ground wire also be #6?
 
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Old 05-12-09, 07:56 AM
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The equipment grounding conductor would usually be #10 copper to match #6 copper hots. A #8 ground could be justified in some circumstances.
 
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Old 05-12-09, 08:10 AM
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The #6 was a hypothetical..is there a calculation for ground wire size? What if it was a 2/0 feed?
 
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Old 05-12-09, 08:25 AM
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What determined the size of an Equiptment Grounding Conductor is the rating of the circuit-breaker that protects the conductors. Table 250.122 is referred to when determining the size of the EGC.
 
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Old 05-12-09, 08:28 AM
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NEC Table 250.122 lists the required minimum equipment ground conductor size for the given maximum overcurrent protection device. The actual size of the ground may have to be adjusted up however based on both the breaker size protecting the hots and the size of the hots themselves, so without knowing how exactly your hypothetical #6 or #2/0 was used, I can't give an exact answer for the ground size.

In the most typical case, #2/0 copper hots would warrant a #6 copper ground.
 
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Old 05-12-09, 08:38 AM
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I am not looking for an exact answer or an exact wire size, this was something I was thinking about when I replaced a disconnect switch last week in my garage. I was simply curious.

Thanks for the comments.
 
 

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