Can I convert my shop to 220v? My shop has 110v ran to it with no sub panel. I would like to add a sub panel to my shop and run 220v from it for my air compressor and 110v for my lighting. Or what is your take on buying a 5000 watt converter?

  • 3
    @Rob: shop equipment that requires 220V is likely to draw way more power than a standard 120V circuit can provide. – Hank Jun 29 '16 at 11:36
  • Thanks fellows, does anyone know what I need to do to make this work? – Terril Fugitt Jun 29 '16 at 12:29
  • What about a 5000 watt 220-110 step up/down converter? – Terril Fugitt Jun 29 '16 at 12:40
  • How much power do you need at each of 220 and 110 in your workshop, and what's the amp rating of the feed to your shop? And, fo course, how much do you want to spend? It might be cheaper to pay an electrician to extend the 220 feed to your main house over to a new panel in your shop. – Carl Witthoft Jun 29 '16 at 12:42
  • There is very little chance of a 5000-watt transformer being a workable solution for your compressor. Even a much lower-rated compressor draws more than 5000 watts when starting. The cost-effective option is Tester101's answer below. – Joe Makes Things Jun 29 '16 at 15:04


  • Pull four appropriately sized conductors from the main panel, to the new shop panel.
  • Install a properly sized double pole breaker in the main panel, and connect the four conductors properly in the main panel.
  • Connect the four conductors properly in the shop panel, making sure the neutral bar is isolated from ground.
  • Install a grounding electrode system (if the shop is detached from the main building).
  • Bond the shop panel to the grounding electrode system.

What you actually want is useful power, which is measured in Watts (W) or more accurately VA (really), itself defined as Volts x Amps. Common USA outlets can't deliver much power.

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That step-up/down transformer is no help. It can change voltage, but it can't change the amount of power the outlet can serve.

A sub-panel is a straightforward affair as Tester101 describes. My only addition is to "think big" - get a much larger panel than you need. Homeowners get stuck all the time when they run out of spaces in their panel. More spaces in the panel are cheap - in some cases it comes with free breakers.

And if the routing is complex, consider conduit - this lets you pull any wires you might want in the future.

You can re-designate your circuit 240V without running any new wire.

  • Get a 240V 2-pole breaker instead of the 120V.

  • Put black tape on both ends of all the white wires, to redesignate it as a "hot".

  • Change every outlet to NEMA 6 type.

  • Change every hard-wired load to a 240V load. Note that many lighting products made today are multi-voltage 100-277V.

At this point you will have nowhere to plug in 110/120V loads. You can power them off that step-up/down transformer you mentioned, although 2000W is big enough.

  • A nit: power is Volt-Amps whenever there's AC power with a phase shift. – Carl Witthoft Jun 30 '16 at 13:08

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