I follow a simple rule: Nothing under-rates the breaker. 20A Breaker=20A switches=20A outlets=#12 wire or better. I know this rule isn't always adheared to by everybody, but why take a chance when the risk is a fire? On a residential lighting circuit that specs 15A switches, I use a 15A breaker with #14 or better wire. Period. YOu won't be tagged for doing it right...
