why do smokes randomly go off??

[jenions]

why would a mains powered smoke alarm just randomly go off??

 

[ezzzekiel]

usually when the house catches fire

is it wired from another circuit or on its own?
dust getting into the unit from above?
battery dying?

 

[davelerave]

cold weather can cause problems too

 

[eskimo39]

If anyone in the house is using deodorants or air fresheners, the particles in these can set them off.

 

[chris gray]

steam can set them off as well.

 

[RexT]

Hi jenions,

Does depend on the type of smoke alarm. Basically they are particle detectors and there is a threshold limit. Typically ionisation smoke alarms react to tiny particles from fast flaming fires and optical larger particles from slow smouldering fires.

They can be affected by steam or anything that produces particles which can enter the sensing chamber. Dust can be an issue as other stuff like that. Positioning is very important.

Electrical interference may be an issue from items that dont comply with the EMCregs etc.

Best advice, keep them clean and bagged if installing on new builds until the works are finished.

Hope this helps a bit,

best wishes

Rex

 

[chris gray]

forgot to say florrys can effect them

 

[alarm man]

If anyone in the house is using air fresheners, the particles in these can set them off.

those plug in ones cause a few problems,

 

[russty]

cold weather can cause problems too

Yeah as it has just turned winter time overnight!

 

[davelerave]

Yeah as it has just turned winter time overnight!

really

 

[leeweimaraner]

i think the reason they are going off is because you have connected them incorrectly,the first detector requires a supply ?but the yellow cable is for interconnection of other smoke alarms (its not an earth)then 3 core between other smoke alarms live neutral and monitoring colour yellow otherwise you get an in balance to earth which trips your rcd

 

[accordfire]

i think the reason they are going off is because you have connected them incorrectly,the first detector requires a supply ?but the yellow cable is for interconnection of other smoke alarms (its not an earth)then 3 core between other smoke alarms live neutral and monitoring colour yellow otherwise you get an in balance to earth which trips your rcd

Can I have some of whatever you've been smoking please?

I have no idea at all, what any of the above has to do with smoke detectors activating spuriously, which is what the OP wanted to know about -

Not only that, if you are wiring anything using yellow sheathed wires in this day and age, you need to go get your qualifications updated FAST.

3 and Earth is Brown, Black, and Grey - and has been for a long while now.

As for earth faults - very unlikely on any BS smoke detector as the earth terminal, if provided is NOT electrically connected to any part of the detector, and earth is used purely for protection on the cable.

 

[accordfire]

While we're on the subject, there are a number of reasons domestic (i.e. interlinked, or non interlinked) mains smoke detectors will activate for no apparent reason.

Number one reason is likely to be the fact you've installed an ionisation type smoke detector in a draught corridor.

Number two reason - back up battery is kerput! Silly little 9V dry batteries should be replaced annually, whatever the manufacturer says - if the detector has been tested at all, that battery has been used, and will lose charge. And the detector *should* have been tested, after all.

Number three reason - build up of dust in OPTICAL type detectors. It's akin to myopia in humans, and means the detector cannot "see" properly - and thinks the dust is a smoke build up.

Number four reason - incorrect choice of detector for environment - e.g. similar to one, but down to things like toast, cooking, burning, heavy smoking.

 

[Tillywolves]

You have to remember that an optical sensor uses an led and receiver, and any dust, particles will set it off... You just need a particle large enough to reflect the light onto the receiver...

 

[millwall ken]

why would a mains powered smoke alarm just randomly go off??

General house dust build up on the sensor?

 

[RexT]

Hi guys,
I agree with the above comments and there are a number of reasons why a smoke alarm / detector may be triggered into alarm state.
One way to think of them is that they are designed to detect particles and as said above dust or any particles can cause this. The key is to use the correct type of detection in the correct location. Maintenance is an important issue and in domestic smoke alarms this is rarely done correctly.
Using a vaccuum to remove dust on a regular basis from around the entry ports of a detector normally is beneficial and gives the unit the most life. However once the unit is contaminated they are not designed to be easily opened and as such the damage will have been done. Most contaminated units react by being more sensitive than normal depending on the level of contamination.
I think Bill is right and replacing the batteries with good quality ones is a good thing on a regular basis. Most are designed to provide a warning when the battery becomes low or out of specification. Some units monitor the sensor and this also can give a single chirp alarm.
Hope this helps,
Best wishes
Rex

 

[Tillywolves]

I remember being called out to an old peoples complex. Fault was reported by occupier of room that the smoke alarm keeps going off...

Got there, and it was a conventional fire alarm system, not domestic smokes. The detectors didnt have an internal battery or sounder. Told tenant that it wasnt the fire alarm that was going off..

As I was leaving the home, the warden called me back, as the tenant, an old lady, had just called her on the intercom, and said the smoke detector is sounding again...

Bemused, I went back to the room, and the lady was adamant that the siren was going off.... I sat in her room to see what was causing the noise. Minutes later the woman said, "its there again, I can hear it." It turned out that the noise was her hearing aid feeding back...

Sometimes you just cant trust what someone is saying to you....

The smokes could be faulty. Are both going off, or just one. You could temporarily remove the link between the two units, to see if it still happens. Then replace the faulty one.

The majority of false alarms I get with opticals, are ingress of dust or insects.

 

[IQ Electrical]

Had a callout just before Christmas to a workshop using extra gas powered heaters to combat the low temperatures, the condensation at roof level was dripping from the steels and triggering the smoke detectors.

 

[manda]

I stripped and decorated a friends hallway last year, the dust totally wiped out the wired in smoke alarm, even though I'd disconnected it and put in another room. It still managed to get in the sensor! Luckily it was a council house so the council kindly fitted a new one. Next time I'll save myself the hassle and put them in a ziploc bag too!

 

[IQ Electrical]

Were you shot-blasting it?