Using a circuit breaker as a daily switch?


I moved into an old apartment about 6 months ago. This is a fairly old building and has an interesting heating system. The heat is “controlled” by a thermostat however, it seems the thermostat does little to nothing when adjusted.
There is no actual on/off switch (believe me, I’ve looked, it’s a small apartment) so I’ve resulted to adjusting the heat by using the circuit breaker switch, which is located in the living room. It is a dedicated switch on the breaker which only controls the heat, and no other outlets/appliances. Written on the breaker is “QO Load Center. 100 Amp. Mains. Series A12”

Now the question is: will this eventually damage the circuit breaker?

I probably flicked the breaker 3-4 times a day this past winter. So far, so good.
I’ve done some Googling, and have gotten mixed answers with little to no support, so I’d like some informed answers please!

Thank you.

Is it a rental or do you own the apartment? If you’re renting, the landlord needs to fix the thermostat. If you own it, thermostats are cheap and easy to replace. You should be able to do it in less than 15 minutes.

Eventually? Yes.
All switches wear out. The more you use them, the faster they will fail.

But, it might take many thousands of cycles until the breaker breaks, so I wouldn’t worry about it too much. Breakers are a lot more expensive than mere switches, so it’s always a better plan to use a switch (if you have one).

Circuit breakers are not designed to be an on/off switch. You need another solution.

Also, if the breakers are old, it could be hard to find replacements for them when they do wear out.

Does this building have multiple heating units or is it just one furnace for the entire building? I think your breaker box may just happen to control the entire building’s furnace. It’s entirely possible that you are making yourself comfortable while making all of your fellow tenants uncomfortable.

Why not just contact the landlord about the apartment temperature? The thermostat may have been intentionally disconnected so that one tenant can’t affect the temperature in other apartments.

Call it a fluke, but the only time I ever use a circuit breaker as a switch*, I wore it out in a few months. 1-2 cycles per day, well under 500 ‘flicks’.

*I was on a ‘time of use’/on demand option with my energy provider. So I would turn the electric water heater off during the day and back on at night via the circuit breaker. All in all, I saved about $20 a month (not worth it for all the inconvenience).

This is almost certainly a code violation in your municipality. A circuit breaker is designed to be a safety device, not a control switch. If it is used for control it will eventually fail. This is very unsafe and you should report it to the building manager if you are renting.

If you are a homeowner, you need to bite the bullet and call a licensed electrician in and have him/her troubleshoot why the switch isn’t working and repair it,repair the wiring associated with it or replace whatever needs to be replaced. For additional safety, especially if you have used the breaker as a shut off more than a few times, you should have that replaced as well.

yes it will wear out sooner. it is a safety device that you don’t want it to wear out or break.

get the thermostat repaired or hooked up correctly.

This is the correct response.

Not an engineer but from my experience circuit breakers appear to be made from some very high temp phenolic type plastic that is temp resistant but very rigid and prone to fracturing with repeated use. The heavy spring action of a circuit breaker puts much more physical stress on this somewhat brittle plastic than a conventional light switch does on its assembly. Over time it will be prone to wear and fracturing.

Yeah. I’ve broken a breaker just by flipping the switch. (plastic nub broke off)

This is definitely not something you want to be using constantly. They are not meant to be flipped “thousands of times” : under what circumstance under a normal operating lifespan (even if the breaker lasts 50 years) would it need to be flipped thousands of times?

A typical breaker ought to only be flipped dozens of times at most over a 50 year lifespan.

On the other hand, when you finally break the breaker, it’ll run you about $40 to replace a 100 amp breaker. The tricky bit is that only a licensed electrician is supposed to open the panel to do the swap : it’s dangerous in there and easy to get shocked.

So if you own the apartment, it might actually be cheaper to replace the breaker when it breaks, if you are desperate. Fixing the thermostat might just involve replacing the thermostat itself (less than $20) or it might mean changing out the control circuit board or relays on the electric heater.

Consider this: What will you do when it finally breaks? Will it break in the off position or in the on position? Neither of those sound like fun.

Slight correction to my earlier answer: You can use a circuit breaker as a switch on certain types of lighting. However, using it as the sole control switch for other devices may not be legal in your jurisdiction. The NEC (National Electrical Code, the book from which most municipalities draw their individual code laws) states in Sections 240.81 and 404.10 that circuits CAN be used used in certain situation as control switches.

However many municipalities START with the NEC and then make their codes tougher. When in doubt, it’s always good to call the city or county and ask them.

As Habeed suggests, it might be simple or not, to replace the thermostat. OP hasn’t indicated if he thinks the problem is simply that the thermostat doesn’t work, or if there is some deeper problem with the furnace not responding to the thermostat.

IF you can fix this by simply replacing the thermostat, note that there are thermostats available that include an on/off switch in them; not to mention all the modern “smart” thermostat that can be programmed with all sorts of elaborate heating schedules.

So perhaps the first thing to try, would be getting a new thermostat that has its own on/off switch in it.

Thermostats can be very easy or not to change depending on the system and how it has to talk to the furnace. It could be as easy as removing it and touching 2 low voltage wires together to get the furnace to fire then untouch them to get it to turn off. But there are other options and some hard to find ones.

Also noted above this thermostat may not even be attached to anything and you may be killing the heat to others as well.

So the first thing is research the thermostat, not replace it. Well first thing sounds like contact the landlord.

Is it wise? no. Can you get away with it? yes.

I’m a bit surprised the heater is a 100A circuit – must be a big space!

I moved into a 15-yr-old house with an in-ground hot tub, and the only control for the circulation pump was the circuit breaker. Doing the math on a 1/4 HP electric motor, it looked like it would be $30/month to leave it running, even if the heater is off, so I used the circuit breaker nearly daily for two years, and then I put in a sensible control system. That was a 20-amp 240V circuit.

I know a few other cases where people used breakers daily, with no repercussions.

But Keeve’s point, and the fact that replacing the thermostat is trivial, would convince me to replace the thermostat without a second thought. If THAT doesn’t work, I’d still get a technician to look into the heating system to see why it’s not operating correctly, and if you don’t know what’s broken, you don’t know what the consequences might be. That’s assuming you own, and that if you rent, you’d already have called the landlord rather than asking us.

The QO series was introduced by Square D 59 years ago, and is still the most sold circuit breaker. So not being able to find a replacement is very unlikely.

A regular 'ol circuit breaker shouldn’t be used as an everyday on/off switch. They are not designed nor tested for high endurance/high cycle use. As noted by others, there are a few exceptions:

  1. If the circuit breaker has the “SWD” marking, it means it can be used as a switch for fluorescent lighting.

  2. If the circuit breaker has the “HID” marking, it means it can be used as a switch for fluorescent lighting or as a switch for high intensity discharge lamps.

Note that since a HID circuit breaker can be used as a switch for fluorescent lighting or high intensity discharge lamps, the HID has superseded the SWD. I’m pretty sure manufactures no longer even make SWD circuit breakers.