View Full Version : Max Circuits in a Sub Panel
Cobraguy
Dec 7, 2007, 07:30 AM
I have a 100A sub panel in my attached garage that is fed with 6/3 (copper NM-B) off a 40A breaker in my main panel. The panel has 6 slots and will handle 12 circuits. Now, my understanding is as long as I don't have more than 6 circuits on this sub panel, I am not required to run the feed through a main breaker at the panel. It doesn't have provisions for a main, so it would have to be back fed. I currently have two 240V 20A circuits and two 120V 20A circuits. That's a total of 6 breakers, but since I'm using combo breakers, it's only in 4 slots. I would like to add a couple of more circuits. My interpretation of the NEC says I can do this without needing a disconnect (main) at the sub panel as long as the total number of breakers in the panel only require 6 hand movements to shut down the entire panel. Correct or wrong? In other words... since my two 240V circuits are on tied breakers, they only count as one because the circuit can be shut off with one hand stroke. Please enlighten me if I'm wrong...
tkrussell
Dec 7, 2007, 08:18 AM
Where in the code do you find " sub panel "?
The Six Switch Rule is for the Main Service Disconnecting Means. In otherwords, instead of having one breaker as the Main to shut down a service to a building, no more than six switches or breakers will suffice.
This is not necessary for a "subpanel", which would have a branch circuit breaker that protects the feeder to a subpanel.
A "subpanel" is nothing more than another circuit or feeder fed by the Main service.
So, you have all 12 circuits in the panel available for use.
Cobraguy
Dec 7, 2007, 09:40 AM
Thank you TK. I figured a panel was a panel was a panel. I also had a knowledgeable person tell me that my sub needed a main if I went over the six breakers. I agree with the way you read the rule now that you've explained it.
grjack
Dec 8, 2007, 10:50 PM
TK - since we're on the subject :)
I was at home depot today - guy in elec dept (says he an electrician)
Says in my planned subpanel that since I will have 10 circuits,
I will need a main breaker in the subpanel (I just wanted to use an easier/
Cheaper main lug). I'm in Connecticut - he says CT inspectors consider a
Subpanel greater thatn 6 circuits to be its own main panel, so I need
A main breaker at the subpanel. Is this guy off? I see you are in new england -
Are you in CT?
Washington1
Dec 9, 2007, 03:57 AM
This is not necessary for a "subpanel", which would have a branch circuit breaker that protects the feeder to a subpanel. TK, what about Article 225.33--which reference 225.30?
It is my understanding that if the feeder is suppling a panel on a remote structure, then you either need a main breaker panel as your disconnect (best), or settle for up to 6 grouped disconnects?
tkrussell
Dec 9, 2007, 06:22 AM
Washington, for a remote building, yes, you are correct, per 225.33, a main or no more that six switches is needed at a remote building.
225.30 calls for the ONE OCPD to protect the remote building for the only one supply that is allowed, and must be on the load side of the service disconnecting means on that property,at the main service, and then lists conditions for more than one service if needed to the remote building.
Neither applies for this attached garage.
Grjack, without going into too much personal detail, just let me say I am more than a little familiar with Ct. However, while the clerk may have good advice, best to check with the actual local inspector for your town.
Never use any advice from a store clerk without confirming with an inspector or contractor, unless that clerk can provide a license for that trade.
All of Ct larger cities and towns have their own electrical inspector, I had met many of them, all gentlemen, may I say. One has a saying on his wall, "Arguing with an inspector is like wrestling with a hog in the mud, after a while you realize the hog loves it." He is my favorite.
Many of the smaller towns and villages will use a building inspector that is somewhat knowledgeable of electric, or borrow the services of a neighboring city inspector. Seldom do any use the State Inspector, that I know of. Here is where you may have interpretation issues, with the "fill in" inspectors. Talk to them, they will bend with reason, logic, and discussion of that particular code question.
If your panel is in the building that has the main service, then no main is required by NEC. If a detached building, then yes, one main or no more than six switches. Each local inspector may have their own requirements.
Washington1
Dec 9, 2007, 10:06 AM
Grjack
Got me off track.
Never use any advice from a store clerk
This is a #1 rule! :)
grjack
Dec 10, 2007, 07:01 AM
Tk -
Thanks - since this is a remote barn, I'll use a main brker sub panel.
Washington1
Dec 10, 2007, 01:21 PM
tk -
thanks - since this is a remote barn, i'll use a main brker sub panel.
I'm with TK on starting your own question on a new message board.
Cobra,
Sorry for getting off track! I was so focused on grjack's question, that I though TK was wrong.