I recently upgraded my laundry room from an electric dryer to a gas dryer. The 30 amp circuit was left in place including the receptacle for for the dryer, which was very handy for the floor refinisher to just plug in to. Now that it is getting colder I would like to add a small electric baseboard heater and thermostat to keep the room warmer. I would like to tap the existing 30 amp circuit (my service box is full even if I didn't mind pulling the extra cable) for the heater, possibly by just running a 30 amp plug from the thermostat into the outlet.

  • 1
    Pictures would help. The best answer you can get from what's written here now is convert the outlet (is it surface mount or recessed?) to feed surface raceway to feed the thermostat and baseboard heat. Your heat may not require a 30 amps, if so you can downsize the breaker, so that your wiring extension can also be downsized.
    – Tyson
    Nov 26, 2017 at 19:42
  • Interesting question, and this came up last week. Can you put a 240V/30A plug on a piece of equipment that actually draws little enough to be suitable for a 20A or 15A receptacle? (20A is max 3840W continuous, 15A is max 2880W continuous). Nov 26, 2017 at 20:08
  • Tyson -- I desire to keep the 30 amp outlet available.
    – brainbuz
    Nov 26, 2017 at 20:26
  • Harper -- this is exactly what I'm trying to figure out.
    – brainbuz
    Nov 26, 2017 at 20:30
  • A picture is worth a 1000-words.
    – Paul Logan
    Nov 26, 2017 at 20:58

1 Answer 1


The best way to tackle this issue is to remove the 30 amp plug and replace it with a junction box. Locate a sub-breaker box on the wall and feed it with 10-ga 2-wire +ground cable from the new junction box. With the sub-box you can create two or 3 circuits with different amp loads (15, 20, 30) and wire sizes. Be sure to enclose the feed and any load cables in conduit if they are exposed to the living area. And follow all safety rules, including shutting off the breaker at the main box while the work is ongoing.

  • I'm going with your earlier comment which is to use a 30amp appliance plug to feed the new subpanel. In those rare instances 30 amps is needed the other load should be removed from it anyway. If for some reason the laundry were reverted to using an electric dryer again, the need to disconnect the heater would force a review of the circuit.
    – brainbuz
    Dec 1, 2017 at 17:57

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