Subpanel Ground wire size?

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  #1  
Old 01-12-07, 04:01 PM
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Subpanel Ground wire size?

I'm installing a 100 amp subpanel in a detached garage, have the PVC buried and plan to use a 4-4-4 with a ground, should I use a #8 (4-4-4-8) or #6 (4-4-4-6) for the ground. This is a 33 foot run and I plan to use a welder thats why the 4-4-4.

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67lplc
 
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Old 01-12-07, 04:10 PM
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#8cu is the appropriate grounding conductor.
 
  #3  
Old 01-12-07, 04:41 PM
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stanfortyman,

Thanks for your reply.
Is this a general rule when running 220 with 3 wires that the ground wire should always be 2 gauges smaller than the hots & neutrals? Seems that all the 3-conductor with grounds that I've seen that the ground is 2 sizes smaller.

Thanks for all the help
67lplc
 
  #4  
Old 01-12-07, 05:15 PM
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No, the standing rule is it should comply with Section 250.122 of the NEC. IN your case you are running a 100A remote distribution panel and the table says you will need a # 8 CU minimum to comply. But you could ALSO run up to as large as the Ungrounded conductor as well..which in your example is # 4 but that would be overkill.

Long story short....# 8 CU is fine....
 
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