unless you have an outdated panel - last year i had to replace a couple of 15A breakers in my circa 1968 Federal Pacific panel to the tune of $27/each - circuit breakers are cheap (<$5 for most single pole 15A and 20A). I now have a Square-D/Home-Line panel and breakers are around $4/each.
from my lay perspective, if you've already got 10/2 wire, which is required for a 30A circuit, why on earth would you not put a 30A breaker there? I just picked one up (i'm running a new 30A line for my servers) for $3.97 at the big box store with orange lettering, the price on the L5-30R receptacle was the killer though. I know that you can put a lower rated breaker than the wire is capable of carrying - ie a 15A breaker on a circuit wired with 12ga - but the point is why would you? If your wattage or ampacity is borderline for the breaker (but within the limits of the wire) why not err on the side of caution and put in the larger capacity breaker? the real problem is when you discover that you're routinely pulling more than 12A (80% of 15A) over 14 gauge wire and the choices become - re-wire with 12 gauge or reduce the load(s).
after making sure the circuit wire gauge is correct, remember - breakers are cheap, rebuilding is expensive.
just my humble, and uncertified, ) $0.02 worth.
BeekerC
from my lay perspective, if you've already got 10/2 wire, which is required for a 30A circuit, why on earth would you not put a 30A breaker there? I just picked one up (i'm running a new 30A line for my servers) for $3.97 at the big box store with orange lettering, the price on the L5-30R receptacle was the killer though. I know that you can put a lower rated breaker than the wire is capable of carrying - ie a 15A breaker on a circuit wired with 12ga - but the point is why would you? If your wattage or ampacity is borderline for the breaker (but within the limits of the wire) why not err on the side of caution and put in the larger capacity breaker? the real problem is when you discover that you're routinely pulling more than 12A (80% of 15A) over 14 gauge wire and the choices become - re-wire with 12 gauge or reduce the load(s).
after making sure the circuit wire gauge is correct, remember - breakers are cheap, rebuilding is expensive.
just my humble, and uncertified, ) $0.02 worth.
BeekerC