Building Remodel Wiring

Old 02-12-14, 01:43 PM
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Building Remodel Wiring

I am helping wire an old barn for clasic car storage. The building is 60 ft. x 55 ft. with a roof that pitches from 12 ft. at the eves and 20 ft. in the center. The building only has 100 amp service located in one corner. I have run 50 amp service to the opposite side of the building and am servicing my RV from that. Now the problem. We will be installing 12 light fixtures that require 3 amps on full load. I am wiring them to where I can fire four lamps off one switch and two lamps off another. That switching will be used for all 12 fixtures. I plan on using two 20amp 120 volt breakers for this service. My plan is to put a subpanel near where the 50 Amp plug is. Break the service there and put the full 50 amp service from the main panel in this box. Then put a 50 amp breaker on the RV service, two 20 amp breakers for the lighting and a breaker that will service a welder and compressor. Due to the 100 amp service with 50 amps on the side that will service the lights, RV, compressor and welder, I am thinking that these circuit breakers will need to be used as on/off switches for load control. Kicking the RV off line when the welder and or compressor are in use. The RV will very seldom if ever pull a full 50 amps. The electrical outlets and will use two 20 amp breakers from the main panel. Does all of this make sense? If it does than let's go to the next question. How do I wire (wire size and circuit breaker) for the welder and compressor?
Old 02-12-14, 05:10 PM
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There should be a plate on both of those devices that tells you the necessary voltage or amperage.
Old 02-12-14, 08:52 PM
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You should not have two sources of power of the same voltage to the same building.
Old 02-13-14, 06:37 AM
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It's a little hard to follow your plan, but it sounds like you have a 100A feed into the building into a 100A panel, then you want to add a 50A breaker running to a new subpanel on the far end.

In that 50A panel, you want to add a 50A breaker and receptacle for your RV, and a few 20A circuits.

As long as I'm understanding correctly, this all sounds fine. As you said, the RV will generally not pull 50A, and the wiring is all protected by the 50A breaker in your 100A panel.

On the other hand, you may want to consider setting up the 50A panel as 100A instead (with the larger breaker/wire/panel), so you don't have to worry about overloads. Or maybe run two runs across the building from the 100A panel, one for the 50A RV receptacle and one for a 30A or 60A subpanel. Obviously more wire cost, but then you don't have to worry about devices switching on and tripping a breaker. Just some ideas to think about.

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