Limit to adding circuits?
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?