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Three Phase Motor Power Cable Voltage Rating

Anirood Hasseea

Power Supply - 3 Phase 400V

As per BS 7671, is it acceptable to use 4 cores (Br Bl Gy & Yellow) 300/500V cable be used for 3-phase motors?

What is the recommended voltage rating of power cables for three-phase motors?

Thanking you in advance.

Parents

  • Cable voltage ratings (a/b volts) are a) to Earth and b) between cores, and as 400V 3-phase is 400V between lines and 230V between any line an N or Earth, then  300/500V cable should be adequate.

       - Andy.

  • in reply to AJJewsbury

    Being picky & pedantic.....

    Are these (cable) ratings intended to be rms or peak?

    One could argue that 230V rms (to earth) is really 230 * sqrt(2) = 325V since the cable insulation will be exposed to the peak of the sinewave.

    Equally, 400V rms line-line is 565V peak.

    Sooo... shouldn't we be talking about a 400/600V cable?

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  • in reply to AJJewsbury

    Being picky & pedantic.....

    Are these (cable) ratings intended to be rms or peak?

    One could argue that 230V rms (to earth) is really 230 * sqrt(2) = 325V since the cable insulation will be exposed to the peak of the sinewave.

    Equally, 400V rms line-line is 565V peak.

    Sooo... shouldn't we be talking about a 400/600V cable?

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