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Which Breaker Turns Off the Thermostat?

This article is for you if you’re having trouble determining which breaker turns off your home thermostat.

Thermostats are normally connected to a circuit breaker to protect them from high current surges. It is usually found in the main panel, a sub-panel, or next to or in the heating unit or AC. You might know where this panel is located, but as there are usually several breakers inside, you may be confused about which one is for the thermostat.

Here’s how to tell which one of the breakers can turn your thermostat off:

Unless the breaker is labeled or marked, or the thermostat one just tripped, or the breaker is next to or in the heating unit or AC, in which case identifying the right one is easy, you can check the breakers one by one to narrow down the right one when the thermostat turns off or on. Otherwise, check the home’s electrical diagram or ask an electrician.

Why You May Need to Turn the Breaker Off

You may need to turn the thermostat breaker off if you ever need to completely turn the power supply off to the HVAC.

It is necessary to switch the breaker off when, for instance, you need to work on the HVAC system to fix something or clean it. In these situations, it will be essential to turn the breaker off for safety reasons. You should know where the breaker is located anyway if the breaker trips.

Here’s how to identify the breaker for the thermostat.


The Breaker for the Thermostat

Normally, only one breaker turns off the power to the thermostat completely.

The breaker that turns off the thermostat may be marked ‘HVAC,’ ‘Thermostat,’ ‘Temperature Control,’ ‘Heating,’ or ‘Cooling.’ If you see any of these labels, it is most likely the breaker that will turn off your thermostat. Switching this breaker off should cut the power to your thermostat completely and make it safe to work on the thermostat if that’s what you need to do.

It’s only more difficult to tell which is the right breaker if the breakers are not labeled or the breaker you want is not marked in any way to indicate it is for the thermostat.


How to Know which Breaker It Is

Here are different ways to tell which breaker is for the thermostat if it is not labeled or marked as such:

Label or marking – There may be a label or marking to indicate the room in which the thermostat is located if the thermostat itself is not mentioned or indicated.

Tripped breaker – If a breaker just tripped while the thermostat was being used, then look for the breaker in the off position or between the on and off positions. If turning it on turns the thermostat on, it will confirm that the breaker you just turned on is the one for the thermostat. If more than one breaker is tripped, you must try them one at a time.

A breaker near the thermostat – If you see a breaker located near the thermostat and directly connected to it, it is most likely the breaker you want. See also further below on ‘Cutting Power to the Thermostat.’

With all breakers on – This is a sure way to know which breaker controls your thermostat if you have time to check and another person to help.

Turn the breakers off one by one, or turn them all off first and then back on one by one, to find out which one is for your thermostat. You may need two people for this, one at the panel and the other checking in the home to see when the thermostat turns on or off.

If you still can’t tell, turn the HVAC unit on, then switch the breakers off one by one until you notice the HVAC turn off. If necessary, put the heat on full blast so that you can notice the hot air stopping.

Amperage – The thermostat breaker is usually a low amperage one.

Electrical diagram – If you have one for your home, look there.

If having tried all the above, you’re still finding it difficult to identify the right breaker, you will have to invite an electrician to check for you.


After Locating the Breaker for the Thermostat

Once you have located the right breaker for your thermostat, and the breakers are not labeled, this might be a good time to label them, or at least the one for the thermostat.

This will make it easy for you to identify the right breaker immediately next time.

breaker for thermostats


Cutting Power to the Thermostat

Besides turning off the thermostat by switching off the breaker, you can also cut the power to the transformer which supplies it.

It is typically a low-voltage transformer installed near or in the heating unit or AC. Turning this power off or disconnecting it will also cut power to the thermostat if it is connected there. Make sure, however, that you disconnect the right transformer, as there may be more than one in your home.


Wrapping Up

To know which circuit breaker turns off the thermostat, firstly, you should know where the main panel or sub-panel is located.

If the breakers are labeled, telling which one is for the thermostat will be easy, but if not, we covered several more ways above to help you identify the right breaker. You should know which breaker is for your thermostat in case you need to switch it off or undertake some repairs.




Video Reference

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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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