Main panel is 200 amp
Subpanel box is 100 amp
2006-10-04 00:43:00 · 2 answers · asked by John F 1 in Home & Garden ➔ Do It Yourself (DIY)
That should read AL, not AU! lol
2006-10-04 02:54:37 · update #1
If the sub panel is rated at 100A the feeder breaker from the main panel should not exceed this rating. This will require 3 gauge wire minimum.
You can reduce wire size if desired, but only if the feed breaker rating is reduced as well. For instance it would be perfectly acceptable to use 6 gauge wire if you installed a 60A breaker.
2006-10-04 01:36:24 · answer #1 · answered by Warren914 6 · 0⤊ 0⤋
The prior answer was for COPPER (the 3 AWG). For 100A on AL (I assume you meant that and not AU) is 1 AWG. You have 2 AWG which has a limit of 90 A (assuming you have 75 degree terminals, 75A if not). You ask what size circuit breaker should a subpanel box have. The 90A or smaller circuit breaker needs to be at the source of the feeder (in the main box). The size of the main breaker can be anything since the feeder is protected.
This kind of work is really past most DIYers. Are you really qualified to do this work?
2006-10-04 01:52:03 · answer #2 · answered by An electrical engineer 5 · 0⤊ 0⤋