Wall Heater Wiring

Discussion in 'Electrical Forum discussion & Blog' started by toolguy504, Aug 10, 2009.

  1. toolguy504

    toolguy504 DIY Junior Member

    Messages:
    20
    Location:
    Chalmette, Louisiana
    I plan on installing wall heaters in two bathrooms. They have two kind that I am looking at. Heater (1) specs are 120 volt, 15 amps, 1800 watts with wire size 12 AWG. Heater (2) specs are 240 volt, 8.40 amps, 2000 watts with 14 AWG wire. Both heaters are the same price. I will be running 12 AWG wire regardless of which heater I use.
    What I would like to know is if I use the 240 volt heaters can I run them together on the same circuit? The distance from the panel box to the last heater is about 50 feet. I figure a 25 amp circuit with 12/2 wg should work. Or should I get the 120 volt heaters and just run 2 seperate 15 amp circuits to each. Thanks. Earl
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,003
    Location:
    New England
    I know 12g is good for 20A, not sure about 25 or if you'd find 25A breakers. If you have room in the panel, I'd run 220 and control each from its own circuit. See what the pros have to say...
  3. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    If the ampacity allows you to run them together the 15A heater should be closer to the panel. I doubt it does, but you're OK on voltage drop with #12 at this total current.
    Last edited: Aug 10, 2009
  4. toolguy504

    toolguy504 DIY Junior Member

    Messages:
    20
    Location:
    Chalmette, Louisiana
    I'm sorry. I did not mean to say 2 seperate 15 amp circuits. I meant to say 2 seperate 20 amp circuits. Thanks. Earl
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,631
    Location:
    Cave Creek, Arizona
    wire

    If you use 25 amp breakers then switch to #10 wire. The size of the wires determines the breaker size, and #12 is only rated for 20 amps.
  6. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    Using the criteria mentioned in the lead post the answer is no.

    The poster stated he would use 12-2 cable. The total current for two 240 volt, 8.4 ampere heaters would be 16.8 amperes. National Electrical Code states that fixed resistance space heating equipment branch circuits MUST be designed for 125% of the full load current which in this case would be 21 amperes. Number 12 wire is limited to a maximum of 20 amperes.

    In order to run both heaters on a single branch circuit the branch circuit would require a minimum ampacity of 21 amperes and that would require a minimum of number 10 conductors with a branch circuit overcurrent protective device (OCPD, i.e. fuse or circuit breaker) rated at either 25 or 30 amperes.
  7. toolguy504

    toolguy504 DIY Junior Member

    Messages:
    20
    Location:
    Chalmette, Louisiana
    Thanks for the replys, especially from Furd. I think I will do as Jadnashua suggest and get the 240volt heaters and run each on it's own 20 amp circuit. Earl
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