# What size wire and breaker will it take to run a 15kw heat strips?

I am getting a total electric heat pump installed and the contractor is say it will take a 90-100 amp breaker and that I have to upgrade my meter base to 200amps. Based on the electrician 15kw would be divided by 240volts to give you 62.5amps. who is wright.?

• Blue F

Watt = Volt x Amps

Thus 15000 =220 x ? That is 15000Watt = 200Volt x 68.2Amp

We use 220 instead of 240 just to be safe (One does not always get 240Volt on the circuit, but it is the peak)

The above is true when there is zero loss. To be safe add 20% (80% efficiency) to the amount of amps. Thus 68.2 x 1.2(20%) = +-81 Amps will be consumed. Also when the heat pump is started the amp usage will spike to well above 90Amps the get things running.

Conclusion: The Contractor is right

• svt

That is a lot of Juice. Any electrician bases total load to 80% of what the wire can handle in amps. Upgrade your panel, the contractor is correct.

• hvacbossman

The contractor is right, as voltage drops the amps go up, and per the mfg specs the max breaker allowed would be 90 amps, with 4 awg wire

• charles
6 days ago

#6 wire 60 amp breaker

• cackywalker

It’s a little iffy, because even though you can do the direct amperage conversion, you have to figure the surge of the start up motor, you have to be able to handle that. The contractor is trying to make sure the house doesn’t burn down. It never hurts to go higher. It only hurts if you don’t go high enough.

• Dan S

Power (watts) = Rate of flow (amps) X Pressure (volts)

Kilowatts = 1,000 watts and Watts = AV so you are looking at::

120 volt line 15,000/120 = 125 amp breaker

240 volt line 15,000/240 = 62.5 amp breaker

• busted_glass

I don’t know who’s right, but you need to run at least a 220 volt line. this means you need; 2 double braid b-x wire conduit lines, 2 20 amp breakers. that’s all i can tell you on that.

• ?
4 days ago

15 Kw Heater

• uncle bob