voltage drop calc

[southernboys]

hey guys ive got a question on voltage drop namely can anyone show me the formula? the reason i ask this is ive got a buddy who wants me to wire his shed 100 amps. the distance is 160 feet single phase im thinking #2 copper but need to do the calc thanks

 

[bphgravity]

Re: voltage drop calc

K = R x cm
1000

VD = 2 x K x D x I/
cm

D = cm x VD PERMITTED/
2 x K x I

I = cm x VD PERMITTED/
2 x K x D

cm = 2 x K x D x I/
VD PERMITTED

WHEN USING ?cm? FORMULA, USE APPROX. K OF 12.9 FOR COPPER AND 21.2 FOR ALUMINUM. USE EXACT K FOR ALL OTHERS.

?2?- The length of the wire, there and back. Use 1.732 for 3 phase problems
?D?- The length of the wire, one way.
?I?- The total load in amps.
?VD PERMITTED?- The allowable percent of voltage drop over the circuit.
?cm?- The circular mil of the conductor.
?K?- The resistance of a circular mil foot. Use entire number in calculation.
?R?- The resistance of the conductor.

WHEN CALCULATING VOLTAGE DROP EQUATIONS, FIRST FIND ?K? THEN SOLVE USING THE CORRECT FORMULA ABOVE.