[exak]

Hello I am installing one 240 volt circuit to my bedroom and bathroom and the heater in the bed room is 1600 watts. The heater in the bathroom comes pre wired for 900 watts but can be converted to 1800 watts. So my question is do I wire the circuit for 2500 watts or 3400 watts, one being a 15 amp circuit or the other being a 20 amp circuit

[stanfortyman]

What do you mean "wire the circuit for 2500 watts or 3400 watts"??

Run a 20a circuit using 12/2 cable. That is enough for both heaters.
You can have 3840 watts of electric heat on a 20A/240v circuit.

[exak]

Heater in the bathroom comes pre wired for 900 watts but can be converted to 1800 watts. So at 900 watts plus the 1600 watts (bedroom heater) that makes 2500 watts or 15 amps. And I could put in a 15 amp breaker. BUT does code require the circuit to be a 20 amp because 1600 watts plus the 1800 watts ( that could be converted in the future even thought now it is 900 watts ) I am using 12/2 wire now next question is if I do use a 20 amp with 2500 watts and 12/2 wire is this wrong because it should be a 15 amp circuit

[stanfortyman]

WHO is saying it must be a 15A circuit??

[stanfortyman]

To answer your question from the other thread.

Again, you CAN out up to 3840 watts of electric heat on a 20A/240v circuit.
You can also put 10 watts of electric heat on a 20A/240v circuit if you want.
IT IS UP TO YOU.

[hedlok]

Go easy on him, stan... sounds like you're having a week like I had last week.

[stanfortyman]

Yeah really. You can say that again!

[donf]

Exak,

Stop thinking in Watts! Stanfortyman is trying to get you to understand that amperage is the key to setting up your wiring. For example, if the heater requires more that 20 amp then you must change the cable and the breaker to match the amperage.

Look on the heater's metal panel. You should see the required amperage for the heater.

Amperage gates the size of the wire needed. Voltage X Amperage = Watts.

For example, VAC 240 X 20 Amps = 4800 Watts (Maximum). Always avoid using the max wattage on a household line. Normally you allow up to 80% of allowed amperage on a line. 4800 X .8 = 3840 Watts. Or shown another way, 20 amps * .8 = 16 amps. 240 X 16 = 3840 Watts.

That's the wattage you should not exceed. Please note that that is the what Stan has been trying to explain to you from the git-go.

[stanfortyman]

For example, VAC 240 X 20 Amps = 4800 Watts (Maximum). Always avoid using the max wattage on a household line. Normally you allow up to 80% of allowed amperage on a line. 4800 X .8 = 3840 Watts. Or shown another way, 20 amps * .8 = 16 amps. 240 X 16 = 3840 Watts.

Don, just so you know. Electric heat MUST be figured at the 80% maximum for a circuit.

[sckneu]

Hi everyone -

So am I understanding this correctly?

I have several heaters I am installing:

(1) 6' (1500w / 6.3 Amp)
(2) 30' (500w / 2.1 Amp each / 1000w 4.2 Amp total)
(1) 4' (1000w / 4.1 Amp)

Can I put this all on the same 20 Amp, two pole breaker at 240 V using 12-2 wire?

Thanks!

[sckneu]

(2) 30' (500w / 2.1 Amp each / 1000w 4.2 Amp total)

Whoops - should be 30" not 30'!

[tkrussell]

A 20 Amp 240 Volt heat circuit can have 3840 watts, your's totals 3500 watts, so your covered.

[sckneu]

A 20 Amp 240 Volt heat circuit can have 3840 watts, your's totals 3500 watts, so your covered.

Hi and thanks for the quick reply!

Does it matter how long the runs are for the 12/2 wire? From the thermostat, the longest run would be about 30' to the farthest heater, taking in to account having to snake the wire up/down/around.

Thanks again!

[tkrussell]

No, the footages you are dealing with are not an issue.