Posted by John B [68.69.26.160] on Saturday, January 04, 2014 at 20:00:26 :
In Reply to: Re: Sounds like you are set posted by Dave Horvath [76.125.248.166] on Saturday, January 04, 2014 at 18:29:24 :
Dave: I will assume the #2 conductor from the house to the garage is copper (not aluminum). My voltage drop calculator shows that with a 60 amp load on 300 feet of copper conductor you will have a 2.84% or 6.8 volts drop. An 80amp load gives you a 3.78% or 9.1 volts drop.
Your breaker in the house definitely needs to be a double pole, or two singles with a tie bar, for simultaneous disconnection of the 120/240 volt circuit.
Take a look at the hp. rating of the pressure switch on the compressor. If it is not rated for the hp. of the motor then you require a magnetic motor starter. Also if it is not rated for the hp. of the motor then it should not be pre wired from the ps. to the motor.
I would expect your electrical contractor will install a new 100 amp combination breaker panel in the garage, and probably increase the size of the breaker in the house.
Keep in mind that with the lights on, and a few extras, while you are using your electric welder, and the compressor comes on you will likely be drawing well over 60 amps.
On start up most electric motors draw 5 or 6 times their nameplate amperage to get them up to speed.
PS. Wiring is no hobby. Hire a qualified Electrical Contractor.
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