View Full Version : Wall Heater Wiring

08-10-2009, 09:56 AM
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

08-10-2009, 10:51 AM
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...

08-10-2009, 02:48 PM
120 volt, 15 amps

240 volt, 8.40 amps

will be running 12 AWG wire regardless of which heater I use.
The distance from the panel box to the last heater is about 50 feet.
run them together or
2 seperate 15 amp circuits to each.
#12 fused at 15A?
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.

08-10-2009, 08:17 PM
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

08-11-2009, 07:08 AM
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.

08-11-2009, 11:06 AM
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.

08-12-2009, 04:24 AM
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