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voltage drop calc - help

voltage drop calc - help

voltage drop calc - help

(OP)
hey there and thanks in advance -

I found this article
http://ecmweb.com/mag/electric_basics_calculating_voltage/

and this problem: (480v branch ckt - uncoated copper)
 Determine wire size Run a stranded copper wire 200 ft at 20A.
 you can use the following method. To complete the numerator, multiply as follows: 1.73 x 212.9 ohms x 200 ft x 20A = 89371.2 Dividing the 89371.2 by the acceptable voltage drop of 14.4V gives you 6207 circular mils.

Where is the 212.9 Ohms from?

thanks

RE: voltage drop calc - help

guessing from the info you provided the 212.9 ohms is the impedance of the line in ohms/ft.

RE: voltage drop calc - help

Sounds like an awful high impedance for 1 ft of wire!

RE: voltage drop calc - help

(OP)
thanks -
it is a typo -

2 x .866 x 12.9 (k for cu) x 200ft x 20A = 89371

89371/14.4 (VD branch ckt - .03 x 480) = 6206cm

thanks folks


 

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