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-   -   Subpanel vs Main feeds amp ratio limits? NEC 2005 (http://www.diychatroom.com/f18/subpanel-vs-main-feeds-amp-ratio-limits-nec-2005-a-164697/)

Minot 11-25-2012 09:09 PM

Subpanel vs Main feeds amp ratio limits? NEC 2005
 
I live in NJ in a town that follows NEC 2005 codes. I live in a ~1800square ft. house with 1 primary electric panel. Looking for planning help to prep for design and permit application.

I'm looking to install a new sub-panel (Square D QO 100A / 20 slots / with 100A main breaker) very close to the main panel and feeding it with a 100A breaker. Does feeding 100A to the sub-panel from a main panel that is only 100A cause any code violations?

I'm looking to move a 10-12 breakers off the main to the sub and then add in a breaker to feed in a generator using an interlock kit.

I've researched other items and plan on unbonding / keeping separate neutral from ground in the sub panel. Also using #3 THHN copper with #8 ground through PVC conduit between main and new sub-panel.

Any tips and help greatly appreciated!!

k_buz 11-25-2012 09:17 PM

All a sub panel does is increase the available spaces to install breakers. If you have a full 100A panel, I suspect you will need to upgrade the service to 200A, and then install the sub panel if still needed.

To start, you could list all 240V appliances...Water Heater, Dryer, Furnace, AC, Range, Hot Tub....

Minot 11-25-2012 09:43 PM

The only 240v items are:

- Dryer
- AC

If I didn't upgrade to 200A and kept it at 100A, would I be violating any codes? I am hoping I don't need to upgrade my main to 200A.

jbfan 11-25-2012 09:50 PM

You do not need a main breaker in the sub, unless you already have the panel.

A 60 amp feed should be more than enough.

frenchelectrican 11-25-2012 10:12 PM

You should be ok with the load as you posted there.

60 amp subpanel is plenty big for that useage.

Merci,
Marc

JuzRick 11-25-2012 10:33 PM

Quote:

Originally Posted by k_buz (Post 1060428)
all a sub panel does is increase the available spaces to install breakers. If you have a full 100a panel, i suspect you will need to upgrade the service to 200a, and then install the sub panel if still needed.

To start, you could list all 240v appliances...water heater, dryer, furnace, ac, range, hot tub....


i very well agree...

electures 11-27-2012 09:22 AM

Quote:

Originally Posted by Minot (Post 1060417)
I live in NJ in a town that follows NEC 2005 codes. I live in a ~1800square ft. house with 1 primary electric panel. Looking for planning help to prep for design and permit application.

I'm looking to install a new sub-panel (Square D QO 100A / 20 slots / with 100A main breaker) very close to the main panel and feeding it with a 100A breaker. Does feeding 100A to the sub-panel from a main panel that is only 100A cause any code violations?

I'm looking to move a 10-12 breakers off the main to the sub and then add in a breaker to feed in a generator using an interlock kit.

I've researched other items and plan on unbonding / keeping separate neutral from ground in the sub panel. Also using #3 THHN copper with #8 ground through PVC conduit between main and new sub-panel.

Any tips and help greatly appreciated!!

No town in New Jersey is following the 2005 NEC. AS of 11/7/12 the 2011 NEC has been adopted with ammendments. Follow the links in my signature for DIY in New Jersey.


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