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Attic subpanel

1198 Views 12 Replies 5 Participants Last post by  wraunch
I am finishing out about 900 sq ft of my second floor that is currently being used as attic. The framing is complete. I will have a 18.5'x30' theater with a wet bar and a bedroom in this space. I currently only have a 20 amp GFCI outlet and some keyless lights that are on a shared circuit with my second floor lights. I would like to run a 90 amp sub panel into an unfinished storage space adjacent to the theater. My plan is to run the wire up from the subpanel to the ceiling joist, down that to the edge of the house, out of the soffit and straight down the side of the house, then punch into the crawl space and come out right under the existing 200 amp service panel. The section from the soffit to the crawl space would be run inside of 1 1/2 PVC conduit. Do I need a J box at the soffit and at the bottom when it goes into the crawl? My big question is what size and type of wire do I need for this? I might only wire up 80 amps but I would like to leave myself some headroom so just pretend it'll be 90 amps now.
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90 amps thats stupid go with 100 amps or u might get away with 60
wraunch said:
I don't think there is enough space in the main panel for 100 amps. Believe me I want as much as I can get.

Here's my layout. I need at least 1 20amp dedicated circuit going to my equipment in the theater.
What do u mean by enough space did u do a load calculation . Just because u put a 100 amp breaker in panel doesnt mean it draws 100 amps it only draws what it needs
wraunch said:
I have not done a load calc. That statement was just based off of 3 electricians that cane to bid the job telling me they though the max available would be 90. I don't know exactly how many amps I'll need.
They need to do a load calculation, they cant go off the top of their head. You could put in a 200 amp sub panel in a 60 amp main if u wanted to as long as the loads dont exceed 60
MCB said:
As eastcoastsparky said, you gotta do a load calc to know absolutely, but you should be fine with a 100A sub on a 200A service.

Thats true if a customer had a 200 amp service i wouldnt even think of doing a load calc but if its a 100 amp service i would highly recommend it. Now the ultimate question is what size service does the OP have
Oops he does have a 200 amp service. Doh!!!!! Should of went back and read
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