What can a 15 amp breaker hold (as far as watts). Also 20 amp--30 amp--and 40 amp. Heck we are in great debate over this issue. It's in the book, but many people have their own ideas. I know that we are to use only 80% of it's actual capacity. Example: Lets say a 15 amp breaker can handle 1800 watts max. I would then use only 80% of that capacity. So: 1440 watts would be the most I would put on that one circuit. Would love to hear you input. Heck, debate me down baby! LOL