200A socket+entrance rated ATS+100A sub


Old 05-29-07, 10:07 AM
Thread Starter
Join Date: May 2007
Location: California Central Sierras
Posts: 29
Unhappy 200A socket+entrance rated ATS+100A sub

New install 200A socket will feed service rated 200A ATS with load center.
How should I feed the 100A sub being used for the (non hvac) residential load.
The hvac will come off the ATS load center.
The sub feeder length is about 25' so not much drop. There is the option of 2 subs, one at each end of the house but thats a lot of copper and another 60' of drop.

Seems my options are tube it with thhn or nm.
I normally lean towards tube for the flexability is affords but nm is a lot faster.
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Old 05-29-07, 12:11 PM
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Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,337
What's the load calc on the 100A subpanel? Is it feasible that this panel may need more than 100A someday?

I generally prefer subpanel feeders in conduit unless it's really impractical to do so. The conduit adds protection to the conductors and provides an easier means of upgrade. PVC conduit 1-1/4" allows up to a 125A copper feeder; 1-1/2" up to a 200A copper feeder; and 2" up to a 200A aluminum feeder.

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