0
A 30 amp circuit breaker is needed unless the load is a motor circuit, then it has to be sized to 250 percent of the motors full load amps.
For 30A circuit is needed breaker 30*1.25=37.5 --> 40A.
If load is lamp or heater, then use breaker of group A or B.
If load is motor, then use breaker of groupC or D (very hard start) or special safe breaker for motor - with variable amp setpoint.
See related link also.
By code you are only allowed 80% of the rating of a breaker. So 30x80%=24amps.
24 amps is the MAX allowed on a 30 amp breaker. You would need a 40amp breaker for a 30 amp circuit. 40x80%=32. So you would want a double pole 40amp breaker.
Still curious? Ask our experts.
Chat with our AI personalities
Fran
Ezra
Beau
Add your answer:
Earn +20 pts
What are the standard size circuit breaker amperages?
In North America the standard sizes for breakers are 15, 20, 30, and 40 amps. The 15 amp size breaker is used in general circuit wiring. The 20 amp size breaker is used for dedicated appliance receptacles, hot water tank and baseboard heating. The 30 amp size breaker is used for a clothes dryer. The 40 amp size breaker is used for the electric range.
Should 25 amps breaker be replaced by 20 amps?
For typical residential house wiring 12 AWG wire is required for a 20 Amp breaker. If you change out the breaker for a 25 A breaker you would have to rewire the circuit with 10 AWG. In that case you could up the breaker to 30 Amps. All outlets and switches should be rated at the same voltage and current as the breaker.
Is it safe to use 10 gauge wire on a 20 amp breaker for a microwave?
No, 10 gauge wire requires the use of a 30 amp breaker. A 20 amp breaker is only used on 12 gauge wire.
Can you use a 30 amp breaker when you have need for only 20 amps?
The question is one of protection of conductors (wires). A 30 amp breaker must have a #10 copper conductor or larger for adequate protection. A smaller wire (larger number) such as #12, is not protected by a 30 amp breaker. If the equipment you are powering only requires 20 amps, using a 30 amp breaker and #10 AWG wire is acceptable provided all other elements of the circuit are listed for 30 amp circuits.
Can you mix an 8-3 wire with a 30 amp double breaker?
You never, ever mix wire sizes within a circuit. However you can wire a 30 amp circuit using AWG # 8/3 wire, although that is overkill and AWG #10 wire is what you would normally use on a 30 amp circuit.
