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Thread: Unit heaters

  1. #1
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    Unit heaters

    Can 2 3kw 1ph 208v heaters be installed on 1 circuit? I remember seeing something about 30a max breaker in 424 of NEC.

  2. #2
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    Quote Originally Posted by toomunsch View Post
    Can 2 3kw 1ph 208v heaters be installed on 1 circuit? I remember seeing something about 30a max breaker in 424 of NEC.
    No because each heater draws 14.4A, and 28.8A is too much as a continuous load on a 30A breaker. Heating loads are considered continuous so you are limited to 24A (80%) on a 30A breaker. You'll need 2 20A circuits.
    Electricians do it until it Hertz!

  3. #3
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    Are the units listed at 3kw for 208v or at 240V. This would make a difference
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  4. #4
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    Quote Originally Posted by toomunsch View Post
    Can 2 3kw 1ph 208v heaters be installed on 1 circuit? I remember seeing something about 30a max breaker in 424 of NEC.
    Correct on the 30 amp - see 424.3. Circuits supplying multiple units are limited to 30 amps, though if it is an infrared heater in other then dwelling, it can be on 50 amp circuit.

  5. #5
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    Mar 2007
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    I don't have the guts yet but I think they are just resistive heaters. Thx for the input

  6. #6
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    Quote Originally Posted by Dennis Alwon View Post
    Are the units listed at 3kw for 208v or at 240V. This would make a difference
    You're correct. If they are 3kw @ 240V, they will draw 10.8A ea on 208V, tho the output will be reduced to ~2.3kW. Both could be on one 30A circuit.
    Electricians do it until it Hertz!

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