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1/3hp 115vac starter ??


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#1 relayjockey

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Posted 02 September 2003 - 12:13 AM

Can you start a 1/3hp 115vac motor with a relay contact breaking only the L1 voltage to the motor?

What are the rules for Starting factional HP motors... NEC Rules that is?

#2 grobert

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Posted 15 October 2003 - 12:26 AM

Relayjockey, what you are looking for is motor controller as defined and covered in NEC 430 part G (starts at 430.81). The answer is yes as long as the relay contacts are rated in horsepower = to or greater than your motor nameplate. If it is not rated in horsepower then it must be capable of interrupting the locked rotor current (six times FLA on small motors). Most relays carry a fractional horsepower rating. Be sure yours is rated for the proper horsepower at applicable voltage. Just breaking L1 is fine but I would be sure your common or L2 is grounded ie:(do you read 120 volts to ground from L1?)




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