I am considering purchasing a stationary air compressor to install in my home’s garage. It will require a 220-240v circuit. Currently, there is no existing circuit in my garage that can power the air compressor. In addition, there is only one remaining breaker space in my load center. The garage is located on the first floor at the front of my home, while the load center is located on the exterior of the house, on the side wall, toward the rear of my home. There is perhaps a distance of 40 feet (rough approximation) between the load center and the location where I want to install the air compressor in the garage.

Considering all these, what would be the best plan of action for wiring the stationary air compressor inside the garage? This is a two-story home with attic space where it is difficult to manuever toward the sides of the home. In other words, as I move away from the center of the attic, I would have to worry about getting my head pierced by roofing nails (if I were not wise enough to wear a hard hat, of course)! There is no basement.

The make and model of the load center is Siemens W2424L1125CU. It has 24 spaces and a 125-amp main breaker.

Siemens W2424L1125CU 125-amp load center, 24 spaces

  • You'll need a 2-pole breaker to run a new circuit. The easiest way to get more circuits is to go to tandem or triplex breakers, if your panel supports those, so you can replace one or more of the existing breakers. If your panel doesn't support tandem breakers, you'll have to upgrade it or add a subpanel and move at least one existing circuit over -- either way will make this project more complex/expensive. What is your brand/model of panel? A picture can help too.
    – gregmac
    Mar 7 '17 at 20:57
  • As far as running the wire, that's not really possible to answer without seeing the house. You need to run a wire to the garage somehow: through the basement (if you have one), fishing through the attic, going through walls inside (which may require holes in the drywall), or some combination of this.
    – gregmac
    Mar 7 '17 at 21:00
  • @gregmac—Basic Siemens builder grade panel. I’ll try and add a pic tomorrow and the model number before I leave for work.
    – user56530
    Mar 7 '17 at 21:31
  • 1
    yeah really, you have to run a heavy cable over that way anyway, might as well feed a subpanel and solve your space problem too. Mar 7 '17 at 22:25
  • 1
    No. A full panel is fine, so long as the calculated loads are reasonable. But a 240V breaker takes up two spaces in USA/Canada 240-center-tap standard wiring.
    – Ecnerwal
    Mar 8 '17 at 15:34

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