Proper wire size????


Old 05-10-00, 10:43 AM
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Hello. Could anyone tell me the proper wire size for 220v/40amp service run outside approx. 150ft Thanks.

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Old 05-10-00, 03:58 PM
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hello mlhare,
# 8 wire is what is required for a 40 amp breaker. but whin u take in to consederation the distance of 150 feet and your voltage drop u need to go to #6. useing the forluma
(2 X K X D X I) / CM = VD
K= 12.9 for copper and 21.2 for alumium
D= distance in feet 1 way to load
I= amps of load
CM= area circuler mils of wire
VD= voltage drop permited (3% on branch 2% on feeders) 6.6 V in your case
(2 X 12.9 X 150 X 40) / 16510(cm of #8)=9.376
(2 X 12.9 X 150 X 40) / 26240(cm of #6)=5.899

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