Sub Panel (or not)


Old 07-19-05, 03:09 AM
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Question Sub Panel (or not)

Hi, I recentely bought a home and I am converting a large area at the rear into Three rooms: a Bedroom, a Utility Room (with electric dryer AND 46 gallon electric Hot water heater) and a storage room. Also I plan to add an addition with master br and ba and small office to that same end of the house. The Main Electric panel is at the other end of the house (about 50') and is a 200 amp service. I'm thinking of adding a 100 amp sub panel in the utility room to supply these areas . Is this a good plan? Can I put an electrical panel on an interior wall? How about in a closet on an interior wall? Does 100 amp seem correct? Is conduit necessary? is #2 aluminum wire ok? Thanks for any help!, Dan
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Old 07-19-05, 05:31 AM
Join Date: Nov 2004
Location: USA
Posts: 973
A subpanel sounds to me like a good idea in your situation: lots of wiring to add on the far end of the house from your main panel. Considering you want a dryer, cold water heater (I've never seen the need to heat hot water, lol) and maybe other larger loads on this end of the house, a 100A panel is probably appropriate. You may want to do some calculations where you consider all you'll ever want on that end of the house (hot tub in the M bath?) to make sure 100A is sufficient.

Check with your AHJ (inspector) to see if they will allow you to feed a 100A panel with 2-2-2-4 Al SER cable (three insulated #2 and one bare #4 aluminum as a cable). They may limit you to 90A with that cable (in which case you can still use a 100A panel, but you simply feed it from the main with a 90A breaker). If they approve the use of the SER cable, you shouldn't need conduit except in areas where you may need to provide the cable extra protection. This cable will probably come out cheaper than individual conductors plus conduit (it's under $1.30 a foot locally here). If you use Aluminum, be SURE to use Nolox or similar on the ends of the wire.

Yes, the panel can be on an interior wall. It CANNOT be in a bathroom, nor can it be in a clothes closet. The utility room is probably a good location UNLESS it doubles as a bathroom. Be sure to consider future access when placing your panel so it is easy to add circuits later. A surface mounted panel is easier to get wire into, but does not look as clean as a flush mounted panel (which usually limits you to entering the top or bottom of the panel only.

Finally, be sure to READ UP FIRST! Wiring Simplified would be a good book to pick up, and well worth the $6.
Old 07-20-05, 05:36 PM
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Thanks chirkware... one more thing

Thanks for taking the time to respond. I will check the codes and the future possibilities before i begin as per your advise. You mentioned protecting the 100 amp wire in certain areas. Could you elaborate on that? Specifically, if I run the wire under the house in the crawl space, should i protect the area from where the wire penetrates the floor to the box with conduit. Is the attic crawl space (rancher) a better choice for running the feed?
Also thanks for the reading advise. I will look into it.
PS I'll just pipe my hot water heater backwards and it should work ok... lol
Old 07-25-05, 05:41 AM
Join Date: Nov 2004
Location: USA
Posts: 973
Sorry for the delay...I thought I had responded.

As far as protecting the cable...I used conduit to protect it where it came out of the crawl space and into the wall. More or less anywhere it would be subject to damage. Your inspector would be able to tell you his/her view on what "subject to damage" means. If you are more comfortable running conduit the whole way for greater wire protection, then you would want to run individual conductors rather than a cable (more work, IMO).

I chose to run my SER cable under the house in the crawl space rather than through the attic because it was easier for my situation...My panel box is MUCH easier to get to from below than from above. Your situation may or may not be similar. The attic is nice because it usually doesn't have snakes. The crawl space is nice because it isn't as hot. Go with what works best.

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