# Calculating Cable Loss

Hi,
I am trying to figure out the calculation for the cable loss of a 30 ft cable that is 3 phase and has 4 cables per phase. The cable
resistance is .0000177 per feet with 25.88 amps running through it. The answer is 0.695 kw loss.
Any ideas?
Thanks,
Troy
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Troy wrote:

Yep, someone wrote the question down incorrectly.
-- Sue
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Try Neher-McGrath for an engineer's analysis. For simple resistance use NEC Chapt 9 Table 8 resistances and P=I*I*R for single phase. The NM paper and other papers can be downloaded in PDF format from: http://www.electriciancalculators.com/ampacity/ampacity.htm
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In article

This appears to be a homework problem of the most elementary kind. If you cannot solve it based upon the book and the instructor, think of a different line of study.
The only hint I will throw out is that maybe you do not know the definition of a cable bvs a conductor. Your description of the problem is not stated well.
Bill
--
Private Profit; Public Poop! Avoid collateral windfall!

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Troy wrote:

The answer given is bullshit. Go back and check the data,. R per phase =0.000017*30=5.1*10^-4 ohms At 25,88 A (such meaningless accuracy) the loss is 0.34 watts per phase for 3 phases, (balanced so 4th conductor ahs 0 current) the total loss is 1 watt.
Try thinking- it helps.
--
Don Kelly
snipped-for-privacy@shawcross.ca
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Oops! I was using the wrong voltage to calculate it. I thought this cable was located on the high side of the breaker, is was accurately on the low side.
Thanks for you help.