Unwanted interaction with smoke alarms?

Posted on
Thu Aug 23, 2018 5:20 am
Paul Chernoff offline
Posts: 11
Joined: Jun 28, 2012

Unwanted interaction with smoke alarms?

I have 5 wired smoke alarms (Kidde PI2010), when 1 goes off they all go off. They have been going off, usually 2 sets of 3 beeps, some evenings for the past few weeks. I would check the house, no problems, and the alarms will stay quiet for at least 24 hours. I think I figured out the problem last night but I would like your opinions.

I use X10 and Insteon technology to control the lights in my house, they send signals on the house's electrical lines. It occurred to me last night when the smoke alarms go off erroneously the smart home controller is sending a signal to turn off a light in the house. Is it possible that the signal on the electrical line is being interpreted by the smoke alarms to mean that another alarm has detected smoke? This is strange because I have had the alarms for 2 years and the other technology for 6 months and this problem is only a few weeks old.

Has anyone had this problem? If so, any solutions? I am deactivating light turnoff actions in Indigo for now and sending the turnoff commands via my iPhone for now. This way I will not get waken up at 2am. If I go a week with no incident I will reactivate the activities related to turning off the lights. I will first test the 3 X-10 devices and then the Indigo devices in case the signal used by one technology causes the problem and not the other.

Posted on
Thu Aug 23, 2018 5:59 am
DaveL17 offline
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Joined: Aug 20, 2013

Re: Unwanted interaction with smoke alarms?

I'm by no means an expert, but my understanding of these systems would suggest that this wouldn't be the case. The systems I've seen (which is admittedly limited) have three conductors that go to each alarm. Two are for power and one is a signal wire. The signal wire is what's used to send messages between the alarms and would be electrically isolated from the power line. It might be possible that dirty power is making one of the alarms unhappy, but the ones I've seen shouldn't interpret that as an alarm state.

That said, these electronic doohickies sometimes do things they're not supposed to do. :D

EDIT: Forgot about ground. :oops:
Last edited by DaveL17 on Thu Aug 23, 2018 5:37 pm, edited 1 time in total.

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Posted on
Thu Aug 23, 2018 4:17 pm
lanbrown offline
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Joined: Sep 26, 2017

Re: Unwanted interaction with smoke alarms?

They run four wires; a neutral, a hot, the ground and finally the control signal. The control signal should be isolated and is only used between the smoke alarms.

It would seem pretty odd that a signal that one device could interpret to turn a light on would match that of an alarm. It is also designed that the fourth wire is sued so that all of the smoke detectors would go off. Since all five are going off, you could also have one detector that is just faulty. There is a recall on the model you listed for not going off when there is an actual fire:
https://www.cpsc.gov/Recalls/2018/kidde-recalls-dual-sensor-smoke-alarms-due-to-risk-of-failure-to-alert-consumers-to-a

Have you thought about disconnecting one alarm at a time and see if it still goes off; if it does put that one back and unplug a different one. After that if it still persists, I would contact Kidde.

Alternatively, you could also just disconnect the signal wire to all of them and then see which one(s) go off on their own.

Posted on
Thu Aug 23, 2018 7:24 pm
lanbrown offline
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Joined: Sep 26, 2017

Re: Unwanted interaction with smoke alarms?

A little bit of research shows that typically Kidde uses 9 volts DC to signal the other units on the signal wire during an alert. So no volts when no alert, 9VDC when there is an alert. I cannot see at all how any Insteon signal could ever cause an issue as it lacks the physical ability to put power on that circuit. I think you just have a bad smoke alarm and you will need to figure out which one. Since it happens on a regular basis, do what I previously mentioned. Another possibility, there is a short in the circuit and that is introducing the voltage. How you would get 9VDC though, I'm not sure. Oh, these units have a 9v battery as a backup don't they? Which would explain the 9VDC on the signal wire.

Posted on
Fri Aug 24, 2018 7:31 am
Paul Chernoff offline
Posts: 11
Joined: Jun 28, 2012

Re: Unwanted interaction with smoke alarms?

Thank you for the replies. Only the last time it went off did I think to check the Indigo logs, and there were 3 separate tasks that turned off switches (both X-10 and Insteon) at the same time. But when I look back the alarms had gone off at times when lights would automatically get turned off. The turn-off times are semi-randomized so I can't say for certainty if the alarms match the Indigo actions, but they roughly correspond.

I am currently deactivated the turn off switch command from Indigo and sending turn-off manually from my iPhone. I will do this for a week and see if the alarms go off on their own. Since I cannot make the alarm go off by command this will take some time, giving every test one week.

The scenario that an alarm has gone bad is possible. Since this problem is erratic it could take weeks of testing to determine if an alarm might be bad.

Thanks for the info on the recall, I will . While these alarms are only 2 years old I would like to replace them. The alarms have limited value because they all go off, I have no idea which alarm has detected smoke. Pretty worthless when you have a basement and two floors, plus I might add an alarm to my attic. I will check with Kidde and perhaps they will replace all of the alarms due to the recall.

Posted on
Fri Aug 24, 2018 5:08 pm
lanbrown offline
Posts: 583
Joined: Sep 26, 2017

Re: Unwanted interaction with smoke alarms?

It wouldn't take weeks. The best solution, you disconnect the signal wire on all of them or maybe just half of them. Say you disconnect the signal wire on the first floor. They smoke alarms can still go off, they just won't report to the others that they went off. So if any on the first floor are bad, when they go off they will be the only ones that went off. Say all on the second floor and attic went off, then that means the issue wouldn't be on the first floor. So now you reconnect the first floor to the signal wire and disconnect the second floor. This means if any on the second floor go off, only the bad one(s) will go off. If they rest go off, then it must be the attic.

You might just go to the attic and disconnect that one from the signal wire and see what happens. If you use Google and type Kidde PI2010 and see the suggestions that Google offers. You will find where some people had false alarms because either dust or dead spiders and bugs caused the issue. With one in the attic, you might just take a look at that one first.

If you look at the specs for it:
https://www.kidde.com/home-safety/en/us/products/fire-safety/smoke-alarms/pi2010/

Temperature Range: 40˚F (4.4˚C) to 100˚F (37.8˚C)
Humidity Range: up to 85% relative humidity (RH)


Does your attic get hotter than 100˚F?

Take a look at this thread:
https://diy.stackexchange.com/questions/21409/should-a-fire-alarm-be-installed-in-the-attic

Posted on
Fri Aug 24, 2018 11:04 pm
RogueProeliator offline
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Posts: 2032
Joined: Nov 13, 2012
Location: Baton Rouge, LA

Re: Unwanted interaction with smoke alarms?

FWIW, we have had terrible luck with both the FirstAlert and Kiddie smoke alarms -- false alarms all the time, and not just on one or two particular units.

The suggestion to look at the attic ones is very good -- of our failures, about 1/3 or 1/2 were caused by the attic detectors. Our electrician had wired those in with great intentions, but the detectors specifically say not to put them up there. Ended up taking several out; heat detectors (not affected by the dust/spiders/insulation/whatever) are fine for the area.

I probably will rip all the in-house ones out and replace with Nest Protects -- from my research they have EXCELLENT nuisance alarm avoidance compared to the others. But $$$... have to save up to do that project!

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