240 volt electric heater


Old 12-14-13, 12:26 PM
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Join Date: Apr 2008
Location: USA
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240 volt electric heater

I bought an electric heater with cord and plug (the cord is 6 feet, 14 gauge) and thermostat (Marley NPH4A) rated at 240 volts, 4000 watts (high), 16.7 amps. The outside of the box shows a 6-20P plug, but the instructions (internet manual) shows a 6-30P plug (the actual manual enclosed was for a 5000 watt heater ?) The unit will be used on a single circuit at a receptacle 42 feet from the electrical panel. I'm hung up on the continuous load question. Could a 25 amp breaker be used on 10-2 wire and would a 20 amp-250v receptacle be used?
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Old 12-14-13, 12:51 PM
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Join Date: Oct 2012
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A few small glitches here. Technically you can only connect a heater of 4000 watts to #10 wiring since the heater is considered a continuous load and #12 wiring is only rated for 16A max.

You can connect #10 wire in up to a 30A breaker. So in your application a 25A breaker is ideal if you can find one.

If the unit is UL rated or listed and it comes with a 6-20P ..... then it is ok to use in that application.

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