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I just moved into a new home, and we have an outlet in the bathroom that was set up for a washer/dryer in case we wanted to go that route. The outlet is a NEMA 10-30R. We are happy with the dryer being downstairs, and my fiance wanted to put a towel warmer on that wall instead. However, I can't seem to find one that is 240V/60Hz, and within my price range. I was thinking the easier route would be to replace the outlet with a standard (US) 120V outlet. Is this possible?

I have replaced a few outlets already and installed a few light fixtures and a range hood, so I am familiar with electrical work, but something like this seems more dangerous to me.

  • It's easier to shop around for a 220 to 110 converter. (make sure it's rated for it) – ratchet freak Aug 11 '15 at 13:49
  • Or I can just find one that operates on 220V. I thought about that, but the 50Hz/60Hz thing might be a problem. – dberm22 Aug 11 '15 at 14:00
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    you'll have 120V/60Hz as output from the converter (only very sophisticated ones will also change the frequency). For a warmer frequency is usually not a problem (pure resistor heating element with a thermo-couple). Timers would have an issue. – ratchet freak Aug 11 '15 at 14:04
  • Any normal electrical wiring in the US will be 60Hz, whether it's 120, 240, or the higher voltage on the utility poles. – Dan Neely Aug 11 '15 at 14:26
  • Yes, but if I get a 220V heater, it will likely be 50Hz (both of which are standard in most parts of the world). Though it might not actually make a difference, as @ratchetfreak points out – dberm22 Aug 11 '15 at 14:30
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+50

First you need to figure out the parts you need. Turn the power to the circuit off and remove the outlet. You need to figure out the gauge of the existing wiring. Since it is a 30 amp circuit, the wire should be 10 gauge, so my answer will mostly assume that.

Now you can go to the store and buy a 20 amp outlet, a face plate, a 20 amp breaker, and a breaker blank cover. Make sure you buy a breaker that is compatible with your panel. Check the outlet to make sure it can handle the wire gauge you have. If you can't find a suitable outlet that can handle 10 gauge wire, then you'll need a couple small pieces of 12 gauge wire, or a short piece of nonmetallic sheathed cable that you've stripped, and some wire nuts.

Back home: Turn off your main breaker and remove the cover from your breaker panel. Disconnect the wires going in to the existing breaker and remove the breaker. Install the new breaker and connect the black wire to the breaker. Find the bus bar where all of the white wires are connected and connect the red wire there. Put the cover back on and use the breaker blank to cover the empty spot you created from removing the double breaker.

Back at the outlet: If your outlet can't take a 10 gauge wire, use the 12 gauge wire to create pigtails: cut a black wire to about 8 inches, strip about 1 1/4 inches of insulation off each end, and use a wire nut to attach it to the 10 gauge black wire. Repeat with white (attach to red) and ground. Connect the black wire to the HOT terminal on the outlet, the white/red wire to the NEUTRAL, and the ground to the ground screw. Then push it all in to the box and put the cover on.

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    Just FYI, electrical code requires all receptacles in bathrooms to be GFCI protected. – Kris Aug 11 '15 at 13:27
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It can be done, but you'll have to swap out the breaker.

A "standard" US receptacle is rated for 125 volts, and 15 or 20 amperes. So you'll be going from a 30 ampere double pole breaker, to a 15 or 20 ampere single pole breaker. You could install a 15 or 20 ampere double pole breaker, but since you're not using the second line there's no point.

In the panel

Install the single pole breaker, and connect one of the ungrounded (hot) conductors to it. Cap off the other ungrounded (hot) conductor, using a twist-on wire connector or other approved means. The grounded (neutral) and grounding conductors should already be terminated properly, so you shouldn't have to do anything with them.

Since you've gone from a double pole breaker to a single pole, there's going to be a gaping hole in the panel cover. You'll have to cover it using a listed and labeled breaker filler plate.

In the bathroom

If You're installing a 15 ampere circuit, you'll have to use a short bit of 14 or 12 AWG wire to connect the branch circuit conductor to the receptacle. Cut a piece of 14 or 12 AWG wire about 6" long, and strip both ends. Connect one end to the 10 AWG conductor coming into the box, using a twist-on wire connector of appropriate size (or other approved means). Connect the other end to the screw terminal of the receptacle. Repeat the same process for the grounded (neutral) conductor, and grounding conductor.

If you're installing a 20 ampere circuit, a 20 ampere receptacle may accept 10 AWG wire. Check the manufacturer's documentation to determine what size conductors can be connected to the device. If it does accept 10 AWG, simply connect the conductors to the screw terminals on the receptacle. If not, you'll have to follow the procedure from above, using only 12 AWG conductors.

Once the receptacle is wired up, you can cap off the unused wire using a twist-on wire connector (or other approved means).

GFCI Protection

Since receptacle is going to be in a bathroom, you'll have to provide GFCI protection. This can be done via a GFCI breaker, or a GFCI receptacle.

Notes:

If you don't feel comfortable working in the panel, don't hesitate to contact a local licensed Electrician.

Before beginning this project, make sure you know which towel bar you'll be installing. Read and understand all the documentation that comes with it, and determine what size circuit you'll need to supply it.

  • Rather than scour the earth for listed and labeled breaker filler plates that shift around and fall out, I often just slap an extra breaker in the space, and label it "not connected". Also, it's the dreaded NEMA 10-30, and there's no ground wire. Fortunately Code requires a GFCI there, so you can just label it "No Equipment Ground". – Harper Aug 1 '16 at 5:37

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