here's a strange one: new light fixture sets off alarm

FroofyCatNovember 8, 2011

I had an electrician replace a ceiling light fixture. Similar style, ceiling flush mount with glass dome, just newer style. Old one had one bulb and had been either a incandescent or compact fluorescent bulb.

New fixtures has 2 bulbs - I put 2 new compact fluorescent in there.

There is a combination smoke and co2 detector just a few inches away from the fixture.

Since new fixture went in this past Thursday, about half the time I flip the switch to turn it on, the co2 detector goes off!

It beeps and says "TESTING! co2 detected in hallway. co2 levels of 0 ppm"

It never went off when the old fixture was there??? I guess if it's just saying testing and 0, maybe I just live with it???

or would you call someone? manufacturer? fire department?

Even more strange, replaced same fixture in upstairs hallway, same detector just inches away, and it never goes off when i flip the light switch.

thanks in advance

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oh, might be worth mentioning the detectors are not hardwired - battery operated.

    Bookmark   November 8, 2011 at 7:49PM
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Detectors can be sensitive. If it were me, I'd move it to a location that's at least several feet away from the light. It also wouldn't hurt to call the manufacturer and see if they think this is weird.

Also, how old is the detector? These units can go bad.

Finally, have you tried new batteries in it?

    Bookmark   November 8, 2011 at 8:17PM
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bought it about 6 months ago.

    Bookmark   November 8, 2011 at 8:21PM
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Interesting phenomenon. Guesses could include that the compact fluorescents emit some electromagnetic signals that affect the CO detector. If the CO detector reacts instantly when the new light is turned on, this would be my first choice as to the cause. If that is the case, additional distance between them will solve the problem. Or that the CF emit some gases (not necessarily CO) that the CO detector can sense. Gases would take some time to build up and affect the detector.

    Bookmark   November 9, 2011 at 7:22AM
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Sounds like a typical cheap CFL that is creating EMI (Electro Magnetic Interference).

The electronics used for smoke and CO detectors is very sensitive, and it does not take much electrical noise to create errors.

    Bookmark   November 9, 2011 at 11:02AM
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thanks for the ideas.

eventually I'll get around to moving the detector.

I guess as long as it's just saying "testing.." I'm not concerned. just annoying for now.

    Bookmark   November 9, 2011 at 1:38PM
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!!! I can't believe nobody caught this one...

The CO detector is detecting zero. Nothing. They don't make noise to tell you nothing is wrong.

Many of them DO announce when they are first powered on...

... the CO detector is powered from the light fixture box. the electrician got some wiring swapped around so that the detector is now getting switched power.

It's more than an annoyance, if you consider the CO detector important, since there might as well not be one when the light is turned off - it has no power, and is doing nothing.

    Bookmark   November 9, 2011 at 7:11PM
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oh, might be worth mentioning the detectors are not hardwired - battery operated

Well pharkus, there goes that idea out the window.

    Bookmark   November 9, 2011 at 7:16PM
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"They don't make noise to tell you nothing is wrong. "

Like any other sensitive electronic device they can be vulnerable to EMI.

Try and use an AM radio near many of the 'electronic' transformers or the lights they are powering.

    Bookmark   November 10, 2011 at 1:41PM
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Wow... teaches me for reading too fast.

In that case, if there's no wires to contend with, move the detector farther from the offending light fixture.

    Bookmark   November 10, 2011 at 6:07PM
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Does the detector have a function where you can test it by pointing your IR(infrared) remote it? The cfl is probably putting out the right light frequency to trigger the test mode.

What is the make and model of the detector?

    Bookmark   November 11, 2011 at 12:43PM
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"The cfl is probably putting out the right light frequency to trigger the test mode. "
It is not usually just a "light frequency" but a light intensity modulated by a specific pattern.
Still possible, but not all that likely.

    Bookmark   November 13, 2011 at 10:27AM
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"It is not usually just a "light frequency" but a light intensity modulated by a specific pattern.
Still possible, but not all that likely.

Actually, if this is one of the First Alert detectors with the IR remote test feature, it would be very likely.

CFLs can emit quite a bit of infrared AND most use internal DC converters that operate around 40kHz +/- 10% for the electronic ballast. So, you easily have 40kHz modulated IR.

Most consumer electronics remote controls use IR modulated at 38 or 40kHz.

Since the test feature is simply looking for IR modulated around those frequencies, the CFL would be a perfect source.

CFLs as well as ironically enough, Plasma & LCD displays, can be a real issue in home theater systems, especially when using when using IR repeaters/extenders.

Curious to see if the OP is using one these First Alert models.

    Bookmark   November 13, 2011 at 3:13PM
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"So, you easily have 40kHz modulated IR. "

You are not going to produce modulated IR at the switching frequency of a power supply.

Thermal effects have a long lag time, and heat from a power supply is not the correct frequency.

IR is a relatively wide band, and heat from dissipated power is not the same as the IR used for remote controls.

    Bookmark   November 14, 2011 at 9:52AM
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"Thermal effects have a long lag time, and heat from a power supply is not the correct frequency."

I did not say the IR comes from the heat of the power supply but is part of the light spectrum emitted by the CFL. The lamp itself is then driven by a 40kHz AC output.

This phenomena of CFLs has been well known for the past 15 years and is a common consideration in the engineering and design of consumer electronics. This ambient modulated IR coming from the lamp saturates the IR detector in equipment and prevents the remote from being read.

In the case of the First Alert detectors (whether used by the OP or not) is that they allow you to use any A/V IR remote to enter the test feature - no code being read - just simply modulated IR produced by any standard remote.

The entire CFL issue was even addressed in 1998 by a joint study done by NEMA and the EIA.

The NEMA document number is: LSD 3-1998 "Interaction of Infrared Controls And Electronic Compact Fluorescent Lamps"

Here is a link that might be useful: NEMA LSD 3-1998

    Bookmark   November 14, 2011 at 8:33PM
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I was running into the exact same issue as mentioned in this post, and between the info in this post and a bit of investigating I was able to fix the issue.

To recap a bit of this posting, yes turning on a CFL sets off a First Alert smoke/carbon monoxide detector. In my case it was model SC07. As mentioned in this post, both a regular IR remote control and turning on a CFL can set off the test feature of the detector.

The First Alert product documentation states that the IR remote test feature can be disabled by opening the battery door, pressing and holding the test button, then closing the battery door while holding the test button until the device chirps. I did this on all of our detectors and have not been able to set them off with a remote control or CFL since.

One note, if you replace the batteries or open the battery door for any reason you will need to go through this process again.

It is ridiculous that First Alert released a product with these issues.

Here is the exact wording from the user guide:

You may need to disable the IR Remote Control feature because your alarm is located in an area that is in the path of your remote control and is setting off the alarm unintentionally. If alarm cannot be re-located to an optimal location, follow these steps:

1) Open the battery drawer.
2) While holding down the test button, close the battery drawer. You will hear a chirp. Your IR Remote Control feature is now disabled.

Note: You can re-enable your IR Remote Control feature by opening the battery drawer and closing it WITHOUT holding down the test button. Remember, when you change batteries, you must follow the steps above to keep the IR Remote Control feature disabled.

    Bookmark   November 22, 2011 at 1:07PM
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thanks FrostyFresh! I'm going to try the IR disable thingie right now. I'm not concerned about the IR test feature because all are low enough to reach on a stool in order to test.

I've been ignoring the problem and did take one detector down that went off the most often. I was assuming I'd need to go buy new ones and hope for the best...

But then the kids got a couple remote control helicopters for Christmas and the dang remotes are setting the other two off constantly! And, they hadn't played the Wii in a while but got some new games and it seems the Wii remotes or maybe the increased use of the tv remote downstairs is setting it off too!

    Bookmark   December 29, 2011 at 1:48PM
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The pic I posted shows my left thigh after surgery for a broken femoral neck bone when I fell only a few feet off a ladder after unsuccessfully trying to use a broom to disengage a battery in a hard-wired smoke detector.

I fell onto carpet and carpet pad, and even though my bone density tests showed all was well, and I'm tall (5'9") and in good shape, I must have hit the carpet and pad really hard because it stopped that detector and the others from going off.

The detectors had been going off for years, only in the very early morning hours and very late at night only on weekends and holiday since I bought this house in Peoria, Arizona. But no one told me. Not one person, including the sellers, bothered to disclose this.

I guess seeing the battery dangling from one of the smoke detectors and wires to electrical outlets in the living room and master bedroom hanging out that the Realtor told me was something the painters did should have given me a clue. But it didn't. I guess I expected that the home inspector -- who I paid -- would have said something, but no. Even when I had no electricity in the living room, part of the kitchen and master bedroom when I moved in, and had to pay a professional "electrician" after the home inspector and Realtor said they were clueless, I still was so stupid I didn't realize that the entire house in this "upscale" section of Peoria, Arizona, had been improperly wired!

The detectors would still be going off if the City of Peoria (Arizona) Fire Department hadn't taken them all down cause they were tired of responding and as they said, they aren't electricians.

After this major injury and surgery (and a total hip replacement after this surgery failed) since I never cook and don't smoke (nor does my dog), I decided to investigate why the smoke detectors had been going off.

I checked to see if they had been recalled, but no. I called the electric company, APS, that serves this part of Peoria (Arizona), but they say there has never been, at any time in history I presume, any problem with their electrical service that could have caused the issue with the detectors.

So I believe anything about electricity, wiring, etc., and home systems at this point. When the air conditioning turns on, my Internet service freezes, drops, etc., although Century Link says it "shouldn't". When I shower, when I turn the water to hot (so I guess it uses more of the water heater power?), the lights flicker. The plug for an electric toothbrush I never had any problems with at my old house (in an older part of Peoria that the city allowed to deteriorate even though I asked the city and council for help) began to smolder, smoke and melt while I was out for a few hours (I kept it).

So I don't believe what companies, home builders (stay away from TowneHomes aka HBT and whatever else), city officials, building inspectors (approved lots of badly plumbed houses in this part of Peoria), home inspectors, real estate agents, and anyone else says. They don't know anything about electricity, so of course they're going to lie.

And if they can get us to keep paying them (monthly bills, taxes, etc.) for lying to us, then the top officials are happy. They don't care about us. I believe all of you with bizarre problems with smoke detectors and everything else electrical.

No one knows how to build homes anymore, especially in the U.S., nor do they want to learn. Those who do know don't want to do the job right because it's "too much work". I have never run into so many people in the last several years who hate to "work".

I don't know why they don't try to get a job as a sleep study subject. How much work can that be?

    Bookmark   March 29, 2013 at 8:20PM
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One more thing: The Consumer Product Safety Commission always seems to be announcing a recall of the CFLs, by last year at this time up to 2 million. That's a lot of lightbulbs.

You can read more at where Edmund Contoski provides a link to a comprehensive report for the Science and Public Policy Institute at: that includes descriptions from people who experienced fires and explosions from CFLs.

I have no doubt that a lot of batteries in everything electrical are defective but that there are never any recalls. HP and Dell recalled (still recall?) batteries in laptops, battery packs and chargers are recalled and so it goes.

So anything could be the culprit when smoke detectors constantly go off. In my opinion, it's just lousy manufacturing. But why bother to make anything well? Corporations might lose half a cent in profit per battery if they made it well.

    Bookmark   March 29, 2013 at 8:35PM
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