Living in an old farmhouse that's hard to heat, furnace quit this fall so I'm using a heat pump, space heater and electric dryer to keep the pipes/me from freezing. I'd like to use a 5000 watt 240v garage heater and forget about the dryer. I have a 50 amp 240v range outlet that isn't used and want to know if I can wire a heater like that to the appropriate plug. It's in a central location in my home and would certainly be more effective than a dryer.

If you have any suggestions on the type of heater I should/could do this with or how to do it I would really appreciate it.

Thank you!

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  • Can you post photos of the plug (or terminal block, if the heater lacks a cord) on the heater? – ThreePhaseEel Dec 16 '18 at 7:10
  • Putting a 5000w device on a 50 amp circuit would be a code violation. – Ed Beal Dec 16 '18 at 19:48
  • @EdBeal -- actually, it's not -- just think of the case of a 5kW cooktop tapped from a 50A range circuit. – ThreePhaseEel Dec 17 '18 at 1:23
  • Corded devices are not taps 180% is the max but I will need to find the code reference. – Ed Beal Dec 17 '18 at 13:12
  • Single non motor operated appliance 422.11.E.3. Not exceed 150% of appliance rated current. If this is a plug in appliance I believe it won't fall under the tap rule, it has a fan motor but the rule allowing a larger OCPD for the motor to start is not valid for a heater. 5kw at 240v =20.8 amps x 1.5 =26.0 amps so a 30 amp breaker would be the max size allowed. – Ed Beal Dec 17 '18 at 16:05

Your concept makes perfect sense, and electric heaters are cheap. For instance a 2000W Cadet heater is $50. Of course that's made for permanent installation, not that that's prevented me from installing one in an afternoon and then uninstalling it the next day. You just have to use correct, legal techniques. The accessories to install electric heat - breakers and wiring - aren't expensive either.

Paying for the electricity, on the other hand...

Anyway, if you want the heater to be cord-and-plug connectd, just change the receptacle to a NEMA 14-30 or 6-30, and put same plug on the heater, and change the breaker to 30A. Breakers are $9. You can also just hardwire the heater, but still change the breaker to 30A.

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  • I agree with changing to a 30 amp breaker and outlet. – Ed Beal Dec 17 '18 at 16:07
  • +1 for the cost of electricity. If you’re paying 20c per kWh then a 5kW heater is $1/hr. Three hours a day and you’re looking at a $100/month addition to your electric bill. – RoboKaren Dec 19 '18 at 16:36

Yes you can wire the heater on that plug as long and the plug is fed with #8 copper wire or #6 aluminum. I would protect the wire with a two pole 40-Amp breaker. The wiring/breaker and panel should be in good shape. That heater will pull about 20-Amps. That much power can be a problem if is not wired on good equipment.

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  • Okay so my first step should be to order a matching plug to be wired to the heater, would you mind if I check back when I have the heater and the plug? I might need some guidance. – JakeP Dec 16 '18 at 7:07
  • Sure. Remember of equal importance to all the configurations and wire sizes is tight connections and quality equipment that is in good shape. – Paul Logan Dec 17 '18 at 6:04
  • A 40 amp breaker would be a code violation on a 20.8a appliance but 30 amp would be ok. – Ed Beal Dec 17 '18 at 16:09

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