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Old 01-23-2010, 08:15 PM   #1
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voltage drop/box fill calc


I am planning on running a 120v 20a circuit approximately 300' to an appliance. i used vd calc formula 2xKxLxI/ cm and came up with a drop of 9.4% for #8 wire and will use 3/4 emt with fittings and pull points were necessary. Number #8 sounds large but run the numbers twice to make sure, what do the pros think?

Last edited by qbert; 01-23-2010 at 08:15 PM. Reason: bad spelling
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Old 01-23-2010, 08:36 PM   #2
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What is the load ?



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Old 01-23-2010, 08:38 PM   #3
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furnace on a 20a single pole recepticle
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Old 01-23-2010, 09:51 PM   #4
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what does the nameplate on the furnace say for total load in amps?
try these two sites to answer your questions on voltage drop & conduit fill. hope this helps good luck!!
http://www.elec-toolbox.com/calculators/voltdrop.htm
http://www.electrician2.com/calculat...alculator.html

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Old 01-23-2010, 10:24 PM   #5
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After looking threw the 08 code book i realize the recommendation of 3% drop which increases the size again making the whole project not such a good plan. Thanks for the responses. I will be exploring other options for a power supply.
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