Can you have several circuits on one breaker as long as you don't exceed the amp rating of the wire and breaker? I'm asking because I don't have any outdoor outlets and my breaker box is full. I know how do the wiring but i'm unsure of standard practices.

 

A "circuit" is defined by the sum of everything on a breaker. Thus your question is illogical. You cannot have more than one circuit on a breaker by definition.

However, you are asking if you can start a new cable at the breaker. The answer is "yes". But be aware that many breakers are not designed to take the direct connection of more than one breaker. Check with the manufacturer to see if yours is. But you can always connect the two wires first, and then run a single wire from this junction to the breaker. Most people agree that you can even make this connection inside the panel box, but I have heard dissention on that opinion.

 

I would first like to say "Thank You" for your prompt answers. I asked that question because some electrical books had me confused. Thanks for clearing that up. Now that i know that I can probably make room in my breaker box because I had my house wiring broken down into very small units which caused the breaker box to fill quickly. Like I said the do-it-yourself book had me confused. I'm getting in practice before taking the IBEW apprenticeship test on the the 27th. Thanks Again!

Mike