A 15-amp circuit uses 14-gauge wire protected by a 15-amp breaker, with a safe continuous load of 1,440 watts. A 20-amp circuit uses 12-gauge wire protected by a 20-amp breaker, with a safe continuous load of 1,920 watts. NEC requires 20-amp circuits for kitchen countertop receptacles, bathroom receptacles, and laundry rooms. General living areas and bedrooms can use 15-amp circuits, though 20-amp circuits throughout are common in quality construction. The critical rule: 14-gauge wire can never be protected by a 20-amp breaker — wire gauge and breaker ampacity must always match. RainFire Builders uses 12-gauge wire and 20-amp circuits throughout most of the home as a quality standard.