Same breaker as the wire ampacity
For example lets say you have a 30 amp breaker and run no.14 wire rated at 15 amps and there is a mild short causing the wire to overheat, but not trip the larger size breaker. What's going to happen? Maybe a fire!
If you run a wire with greater ampacity than the breaker that's OK, but not inversely.
BTW unless I'm all wet, a breaker will stand a momentary overload without tripping as in the case of the motor starting up.
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
Last edited by woodnthings; 12-12-2010 at 07:56 PM.