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#39235 - 06/15/04 08:26 AM Home addition sub panel  
tonyc  Offline
Joined: Sep 2002
Posts: 18
Chesapeake, Va
Doing the electrical for a friend on his 1000 sq ft addition. Main part of the house has an existing 10 yr old 200 amp panel that is full. I was going to put a sub panel in the new addition utility room and either back feed it or just get a panel with a 100 amp main. Can I use a 100 amp breaker in the existing panel and feed the new sub panel with a 100 amp breaker or does this violate the tap rules its about a 50-75 ft run from panel to panel ?

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#39236 - 06/15/04 09:15 AM Re: Home addition sub panel  
Roger  Offline
Joined: May 2002
Posts: 1,716
Tony, no offense intended, but can you legally permit this work not being a licensed EC?


#39237 - 06/15/04 09:41 AM Re: Home addition sub panel  
tonyc  Offline
Joined: Sep 2002
Posts: 18
Chesapeake, Va
I guess today is just not my day. I do have a license two as a matter of fact.

N.C 14766-L since 1988
Va. 2705078514

look em up just renewed

And I let my HVAC go because it was too much headache.

I am a Project manager on Computer networks now so my Electrical knowledge may not be what it used to be. So can I do my friends a favor or do I need to call a contractor. Little bit of adevrtising for your site in Electrical contractor and now we can't even ask a question. It's all good

#39238 - 06/15/04 01:14 PM Re: Home addition sub panel  
Roger  Offline
Joined: May 2002
Posts: 1,716
Tony, certainly you can ask questions.

I asked you one and you answered.

Here's another one do you have or can you access a current copy of the NEC?

As far as your original question, yes, you can feed this new panel from a 100 amp breaker and there is no limit for length of a feeder which is what you would have in this case. (not a tap)

Has anyone calculated how this additional load is going to impact the existing service?


#39239 - 06/15/04 02:57 PM Re: Home addition sub panel  
Radar  Offline
Joined: Apr 2004
Posts: 349
Los Angeles, CA
Tony, If you utilize a 2P 100A breaker in the main panel to feed the sub panel, that's not really a tap, just a feeder circuit. You don't necessarily need a main CB in the sub panel, but it might bu useful for local isolation.

Two things to make sure of:
1. Use adequately sized feeder wire.
2. As noted above, someone should do a load calc on the entire electrical service and distribution system.

I presume your friend is getting a permit for the addition? Did he get the electrical permit also? Most building authorities will want to see this info too.


There are 10 types of people. Those who know binary, and those who don't.

#39240 - 06/15/04 03:24 PM Re: Home addition sub panel  
tonyc  Offline
Joined: Sep 2002
Posts: 18
Chesapeake, Va
Yes they have a permit, I am already thinking it may be more than I can handle they are wanting to move the dryer onto this new panel 1.5 ton ac plus various 110vac circuits they may wind up with a 200amp feed thru at the rate things are going I really don't have the time to do it.

#39241 - 06/16/04 12:50 PM Re: Home addition sub panel  
classicsat  Offline
Joined: Nov 2002
Posts: 456
I might have the A/C on the main, and move some existing 110 circuits to the sub.

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