Need Easy Formula for Voltage Drop

Fast and simple: VD = 2 *K*L *I / CMA for single phase Multiply this by .866 for three phase and multiply by .5 for 4 wire, 3 phase.

K = 12.9 for copper and 21.2 for Aluminum (for 75 degrees C. maximum insulation temperature) L = one way circuit length in feet I = amperes CMA = circular mil area from Table 8 in Chapter 9 of the NEC VD = volts for voltage drop

Or just go to

Presidant of the company and you cant calc VD ?

How bizarre.

sQuick..

He must be the "Son" part...

He could have an accouting/finance/business background.

Sincerely,

Donald L. Phillips, Jr., P.E. Worthington Engineering, Inc.

snipped-for-privacy@worthingtonNSengineering.com (remove NS to use the address)

What he really needs is a chart that gives the voltage drop for one amp in 1000 feet of the various wire sizes. Then it is a simple process that you can virtually do in your head if you just want a "go/nogo" answer.

I would recommend a copy of Ugly's Reference Book

Same thing I thought when reading this one. I thought all those guys had an NEC handbook and an Ugly's reference at least!

Not quite. The application of heat transfer to voltage drop allows the calculation of the conductor temperature that gives a more accurate voltage drop. Ugly's does not have a single line about calculating amperes using heat transfer.

I figured if he didn't have a grasp on things, Ugly's would be a good reference....You already left the equation.....

I*R for DC

Works equally well for AC, since resistance doesn't discrimate.

Harry C.

True, while 'I' says a lot, the 'R' gets a little more complicated with AC. Indeed, Zee issue can get quite complex.

I wonder if he gets it now.

Nice play on words.