I thought hard-wired smoke detectors were supposed to be on their own dedicated circuit.

Smoke detectors are supposed to be on a dedicated circuit. My house is 21 years old. Ether the code was different at the time or the wiring was done improperly. This is the only room connected to the same circuit as the smokes.

To verify it is the treadmill, can you run an extension cord from another room?

Do you have a UPS?

I have not tried an extension cord, but that would be a good first step just to test. (Will actually try that now). No, I don't have a UPS, but wondering if that would work or would be safe to use with a treadmill.

The extension cord works and prevents the smoke detectors from going off. I know extension cords should not be used, however.

If there is a separate/different wiring outlet in an adjacent room, that outlet can be tapped to provide an outlet in the treadmills room.

I asked about UPS because you asked about power conditioning.

Is your treadmill UL listed?

Thank you. It s ETL listed and conforms to UL Std. 1647. (Lifespan TR5500i).

I appreciate your responses.

How about replacing the smoke detector that's triggered with a battery-powered one?

Thanks for the suggestion. One of the first things I tried was to disconnect the smoke alarm in the room where I'm having the problem, but that didn't solve it. Because all the other smoke alarms are still on the same circuit as the treadmill, they are still triggered. My only option would be to replace all 9 of my wired, interconnected detectors (again) with battery-operated, wirelessly interconnected units, which I'd like to avoid.

I am trying a heavy-duty, direct plug-in surge protector first (arriving today), and if that doesn't work, I will need to consider a surge protector with a long extension that I can plug into another room for now. I just want to be sure that whatever I'm using will not be a fire hazard.

A surge protector may not/is likely not going to work, many simply try to clamp/limit any voltage spikes that might appear on the power line. That doesn't stop noise from passing in both directions. Your treadmill is likely using an internal variable frequency or duty cycle power supply to control the motor speed and it is the switching noise from this process that is likely getting back onto the power line and triggering the smoke detectors. Simple surge protectors won't be able to stop this kind of electrical noise from passing through. I think you need a true EMI filter such as this between your treadmill and the incoming power:

https://www.galco.com/buy/Qualtek-Electronics/854-03/003?source=googleshopping&utm_source=adwords&utm_campaign=&gclid=Cj0KCQiAlZH_BRCgARIsAAZHSBkx1NY1NwCUy1KJ2qF5oUzpNn-jS_qaiPTiwDtGuTlA8t0t8JYkHZEaAtR4EALw_wcB

There are many sources for such a filter. It just needs to be sized to the max current draw of what is being protected, and then encased so the connections aren't exposed.

Just circling back after going dark for a bit...

The Tripp-Lite Isobar noise-filtering surge protector didn't work. The treadmill was still triggering the smoke detectors. I was able to get a longer (10 ft) power cord for the treadmill from the manufacturer, so as a temporary solution I am plugging it into an outlet in a room around the corner -- on a separate circuit -- when I use it. Eventually, I'll have an electrician in to look at it. Thanks again to everyone who commented.

I didnt read this whole thing, but from a comment i saw, i wanted to reply.

it read smokes should be on a dedicated circuit.

no, dont do that. put then on with lighting or something else inportant so youre more likely to know if the circuit trips.

we always pull them off an other circuit.

Hi，I want to know how you solved it? I have the same problem now. Thanks a lot

Hi. I'm sorry for the late reply. I have not fixed the electrical issue. Instead, as a workaround for now, I ordered a longer power cord (10 ft.) from the manufacturer of the treadmill so I can plug it into an outlet in my hallway that is not connected to the smoke detector circuit. It's a bit of a hassle to plug and unplug it each time I use the treadmill, but it works.

The best solution is probably to relocate the treadmill. I happened to choose the one room with this issue.

Maybe the treadmill should be on its own circuit.