The 200 amp SQ-D panel I'm working with in a home is full. I need to add about 5-120v circuits and 2-240v out to a new attached garage. I could pull the singles and add twins but some inspectors don't like a lot of twin breakers. I will add a 100 amp sub-panel in the garage feeding it with a 100a breaker (which I'll have to add 4 twins to make room) but think this will be better. Also, will adding the 100a panel be a problem with loading the 200a panel?
Thanks for any input.
Is this loadcenter listed for twin breakers? If so the inspector shouldn't have a problem with it.
The only way to determine if the 200 amp loadcenter can take the additional load is to do load calcs.
Don't think there is a listing. There are twins that will fit in the panel. I will do a load calc and check the amp draw under normal usage too.
There should be a label on the inside of the box that shows what type of breakers can be used in each position. Do you have the catalog number of the loadcenter?
Just because they make tandem breakers that fit doesn't mean you should use them. One sure way to tell is if there will be more than 42 (40 in most) poles/breakers, then the panel is not meant to have tandems. You may have a 30/40 panel that can have 10 tandems, but it sounds like you may run over that. You may need to add the sub panel in the garage and another sub next to the main panel.
I have argued on this board that the 42 circuit limit is ridiculous and 1 or 2 tandems should be allowed, but you sound like you need a lot more than 1 or 2. Also, it may be a code violation, depending on your panel.
Not only is there the 42 NEC limit, but each panel has a limit. Look at the fine print inside the can.
If your 200 amp panel already has 42 full spaces, then your other alternative is to do a load study of each branch circuit, and combine those that you can.
Electric Eagle,
What would the extra sub-panel next to the main panel be for? A disconnect beaker? I would need a way to tap the buss.
The subpanel next to the main panel is for the circuits that are displaced for the feeder connections. If the main panel is full, you need to move four poles to the subpanel, freeing four poles in the main panel. Then, two of those poles feed the new subpanel, and the other two feed the remote subpanel with all the new circuits.
You can, of course, also put some of the new circuits on the subpanel next to the main panel.
SolarPowered, Got it, that makes sense.
If you are not allowed to add twins to a 42 circuit panel, then why could you add a sub-panel?
You can have as many panels as you want.
But each panel is limited to 42 overcurrent devices, not including a main breaker.
When counting the overcurrent devices a twin breaker counts as two, a two pole breaker counts as two.
iwire,
What about the 6 disconnect limit?
Everything is fed from the first panel. Open the main in it and all is dead. One operation of the hand
aldav53, understand your dilema, but why not run 100 amp sub to garage, then pick up displaced/ extra circuits with that panel?
Just an idea, good luck. Scott
srscott, was trying to avoid having to run extra circuits in a 80 ft run. Actually found 2 breakers not being used in the main panel so it worked out good.
I ran a #4 ground wire to a water pipe, plus the ufer ground. But I probably don't need it on a sub panel. There shouldn't be any codes against it.