Power cord(cable) size?

Question

Have a 480 volts 3 phase 16 amp motor. Need 400 ft of extention cord. Is is OK to use a SOOW 10/4 cable, the voltage drop is 2.67%(12 volts). Machine is powerd by a generator that I can run at 500 volts to counter the voltage drop.

8/4 cable cost twice as much, but the voltage drop is 1.7%(8 volts).

Answer 1

If you have the ability to increase the voltage to compensate for the volt drop and the cable has sufficient current carrying capacity, then you are fine. The volt drop will cause a little wasted power but nothing compared to cable costs probably.

Presumably your "boosted voltage" generator wont be powering anything else or that will give you problems

Edit, Cables are rated in rms voltage

Answer 2

I suppose this may work, just remember make sure you don't overheat your cord, and your motor runs ok with this setup, over or under voltage is hard on a motor. try using a volt meter on the motor while under load in order to find the proper voltage for the generator, that % is calculated and may not be acurate in real life.

Answer 3

The only thing about SOOW is that the insulation is only rated for 600 volts, and the peak voltage of a 480 volt RMS system is 678 Volts.  The peak-to-peak voltage is 1386 volts, and two adjacent phases will see a maximum potential difference of almost 800 volts  

This will be unsafe -- the insulation might breakdown (even though that 600 V is a conservative rating).

Two adjacent phase cables will provide for 1200 volts rated total insulation and that is more than the phase-to-phase max of almost 800 volts, so you could take a chance, but I wouldn't recommend it.

As for the wire size -- 10 gauge wire is definitely large enough to handle 16 amps.  12-gauge wire would even be sufficient, especially since you can compensate for the voltage loss.  But, stick with the 10 gauge anyway, for a larger margin.

You need cable that is rated for higher voltage.

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