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    ometek's Avatar
    ometek Posts: 3, Reputation: 1
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    #1

    Jan 9, 2008, 02:38 PM
    Breaker size
    I have a 7.5 hp motor that was wired 480 volts 3 phase rated at 14 amps and I need to change from 480 volts down to 208 volts. What would the breaker size need to be rated for at that voltage.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #2

    Jan 9, 2008, 04:17 PM
    It should be sized according to Table 430.150 of the NEC, and a 7.5 HP motor is rated at 24.2 amps, and the breaker can be no larger than 250%, or 60 amps.

    Don't forget to change the overload heaters that should be in the mag starter controlling the motor. These need to be 125% of the actual running load amps.
    Walkergirl's Avatar
    Walkergirl Posts: 1, Reputation: 1
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    #3

    Mar 30, 2008, 06:58 PM
    I have a travel trailer that is only 30 volts. This limits what can be running at the same time. I would like to change the trailer to 50 volts. Can that be done?
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