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# Calculation of Electrical Cable size

Will u please give the formula, for selection of cable sizing (both Copper and Aluminium) depend upon the electrical loads...
Asked by: Prabakaran Balaraman | Member Since May-2011 | Asked on: May 6th, 2011

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Shreyash Kumar

Answered On : May 24th, 2011

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the determination of cable size in done on cost basis. The most economical area of conductors that for which the total annual cost of transmission line is minimum. This ia also known as Kelvin's Law.

According to it the most economical size comes when
variable part of annual charge= Annual cost of energy

Susanta ku.dwivedi

Answered On : Aug 16th, 2011

First we calculate the amp rating of the equipment.for cu we take 2.5A & for alu we take 1.5 to 1.7A for 1sqmm cable.

mahmoudp1

Answered On : May 3rd, 2012

It depends on a lot of factors like current density for mm^2 temperature is the cable on cable trays or buried or inclosed in PVC is that a 3 phase cable multicore or what and also depends on the voltage but in general making a current density 2 A/mm^2 for copper for simple applications is good.