What size wire do I need to put in a 100 amp subpanel? jeffysan
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I'm using #2 Aluminum SER cable for mine at the end of this week. Meets code in my area.
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J. D. Reynolds
Home Improvements
If you're using aluminum wire then I like to to go with 1/0, which is rated for a full 100a even when embedded in thermal insulation. #1 is OK if run in uninsulated walls or through open space. Copper wire, #2 does it for both. These numbers are from Table 310-16 of the NEC.
#2 aluminum is rated for 90 amps @ 75 degrees, which is what new 100a terminals are (usually) rated. If the wire is embedded in thermal insulation then you use the 60 degree column and #2 Al is rated at 75 amps. People use it for this purpose (subpanels) but I'm not sure it would meet code, and I don't like it because it's undersized.
I think there is confusion about this because the NEC allows #2 Al to supply a 100a service, as long as it is adequate for the load, even though it is not rated for it in the Table 310. But I don't think this translates to other uses.
LEE
Edited 4/25/2007 12:47 pm ET by edlee