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Circuit Breaker Or Overload For Single Phase Motor


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#1 AB2005

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Posted 02 May 2016 - 07:26 AM

Dear Friends; We have 220V, 1HP, 8A, 1430rpm motors for blowers. To protect the motors against overloading, we want to add safety. As normal circuit breaker do have thermal characteristics, so can we use 9/10A circuit breaker instead of overload type circuit breaker 6.5A-9.5A which usually available in 3poles? If a normal circuit breaker costs $3 then a 3pole overload type circuit breaker costs $30. So kindly guide me if we can use the circuit breaker or not if not than what is the reason.
"Don't assume any thing, always check/ask and clear yourself".

#2 rpdodd

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Posted 02 May 2016 - 10:42 AM

You can use a 10 amp breaker but , the motor is drawing 8 amps and you can only put 80% of FLC on a breaker which in this case 80% of a 10 amp breaker is 8 amps. So you will be running right at maximum allowable current for a 10 amp breaker which may cause the breaker to get a little warm depending on how long you run the motor for. If it is running continuously there is a chance of nuisance tripping because of heat but most likely it will be fine. I would use a 2 pole 15 amp as long as your wire size is correct.






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