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Electric Outlet wire/breaker size

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Macrosill

Well-known member
Joined
Mar 21, 2015
Messages
51
Location
Long Island, NY
With 150 foot run and aprox 36 amps you would need to run #6 copper cable to have a voltage drop of less than 3%.

1 conductors per phase utilizing a #6 Copper conductor will limit the voltage drop to 1.99% or less when supplying 36.0 amps for 150 feet on a 240 volt system.
For Engineering Information Only:
55.0 Amps Rated ampacity of selected conductor
0.4662 Ohms Resistance (Ohms per 1000 feet)
0.051 Ohms Reactance (Ohms per 1000 feet)
7.199999999999999 volts maximum allowable voltage drop at 3%
4.772. Actual voltage drop loss at 1.99% for the circuit
0.9 Power Factor
 
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Macrosill

Well-known member
Joined
Mar 21, 2015
Messages
51
Location
Long Island, NY
I am assuming you are referring to Temperature Derating. Temperature derating has to do with conduit fill as well as ambient temperature in the installation area. The higher the temps the lower the ampacity of the conductors. Typically it is used in hot boiler room type installations.

There are temp ratings based on conductor and cable insulation as well.

Call your local inspector and ask him about the installation you have in mind. Some jurisdictions have not adopted the NEC. He should be able to give you some insight as to what is required by your AHJ, Authority Having Jurisdiction, aka electrical inspector.
 

TRWham

Well-known member
Joined
Aug 11, 2017
Messages
1,975
Location
East Cobb County, Georgia
Article 630 covers wiring for welders and plasma cutters. You should be sizing the wire based on 28 amps (the effective input amperage (I1eff)), not 36, but the only harm in oversizing the wire is to your wallet.

Sberry is correct that 8 AWG is the solution for you. The NEC will allow as large as a 60 amp breaker in this case, but I imagine 50 or maybe even 40 would be fine.
 
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