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

and place your mouse over calculators. The voltage drop calculator near the bottom of the menu does it for you. The advanced voltage drop calculator will give even better results for contract work where you really are nit picking to downsize your wire or arguing with the inspector.

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.

145 Greenglade Avenue Worthington, OH 43085-2264

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

614.937.0463 voice 208.975.1011 fax

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

should answer most of your electrical questions....

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

It should answer most of your electrical questions....

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.

> It should answer most of your electrical questions....

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.