Electric Wallboard Heaters Circuit Load
Hi guys, can anyone help answer my electrical question so I don’t burn my house down. There was a 4′ 1000/750 watt electric baseboard heater in my garage. I took off the garage door and put up a wall to convert to a shop. I wanted to add another 4′ 1000/750 watt baseboard heater to the same 240 volt circuit breaker to keep the room warmer. Can I do that or will it overload the circuit? What is the maximum draw I can put on that one breaker? Thanks
Replies
So you have a 240-volt circuit currently powering only a 1000 watt heater. Therefore, it is running at 4.16666 amps. The smallest wire that could be in the wall would be 14 gauge and it would handle 15 amps. The smallest breaker would be 10 amps although that would be exceptionally rare. The smallest common breaker would be 15-amps.
So you could run a total of 3 such baseboard heaters on the smallest 240-volt, 15-amp circuit that might be there.
If it is a 20-amp breaker (and therefore 12-gauge wire), you could certainly run 4 such heaters. And, if you really have 208 volts instead of 240, you could run 5 of them on a 20-amp circuit.
Thanks David, appreciate the response. Makes me feel very much more at ease now about adding the second baseboard heater.
Larry Jacobi - on Triangle Mountain overlooking the city of Victoia, BC.
Hey Larry,
I also overlook Victoria, but not from Triangle Mountain... and also I'm an Electrical Safety Officer for the BC Safety Authority so I know that you'll be obtaining the REQUIRED electrical permit for this work you're undertaking, right? The office is located at #380 - 4243 Glanford Ave (250) 952-4444. Looking forward to hearing from you.
WyrGuy
.....HAHAHAHA ,pretty darn clever WyrGuy , yup....BTW welcome to BT..."
David pretty much covered it. The only question I'd ask, even though it's probably not likely, is if there are any other electrical loads on the same circuit besides the baseboard heater.
I don't believe there are any other circuits coming off that panel breaker, but thanks for the reminder, I will definately look.
Hello, are you sure this is the only heater on the circuit? If so we calculate EBH circuits as follows 20 Amps X 240 Volts = 4800 Watts X 80% (max circuit ampacity) = 3840 Watts.....3820W / 250W per foot = 15' of EBH on a 20 amp circuit
15A x 240v = 3600W x .80 = 2880W / 250W = 11' of EBH on a 15 amp circuit
250W per foot for 240V EBH
187.50W per foot for 208V EBH
Glad you mentioned the 80% design load/safety factor built into the codes.
Some electric heat baseboards may not be 250 watt per foot density though. If the label is still not on the unit, it would be good to contact the manufacturer to find out the wattage or, simpler, measure the current draw and calculate it.