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lameid · Nov 12, 2006, 09:58 AM

I live in KY.

I am comfortable adding circuits to my circuit box but I have a couple questions about doing so...

1) Is there a limit to the circuits that can be added to a breaker box other than the number of breaker slots? I.e. can the sum of the breakers exceed the sum of the main? Obviously I don't think I'd ever hit the 200 amps and trip the main but I am wondering if there is code that says I can't exceed the capacity of the box as a failsafe to a failed and engaged Main Breaker and if not required, is it a practical concern?

2) The wiring coming into my box is getting busy. The knock-outs are all used up (at least the ones I can use a screw driver to hit easily). Is it OK to double up wires coming into the box? If so are there any special considerations?

tkrussell · Nov 12, 2006, 10:17 AM

Any one panel can have no more than 42 circuits. There are breakers that are called half size or tandem breakers that allow more circuits to be added to a panel, if say for example you have a 24 circuit panel ,and need more, but, cannot have more than 42, even if the panel can fit more.

Adding up the ratings of each branch circuit is irrelevant, this is never done, and means nothing. There are many times, if one was to add the branch breakers, the total will come up to and go over the rating of the main. The main is sized according to the calculated total load of the building, and is never compared to the branch circuits.

There are cable connectors that allow for more than one cable into one KO opening. Here is a spec sheet for one. The connector needs to be rated to handle more than one cable.