Interconnected smoke alarm - troubleshooting

[Neptune]

Hi,

I have an aico alarm system which was mains powered and interconnected when installed 3 years ago. It's not been maintained and when I took a look recently, a couple of the detectors are missing. Only the ceiling plate is on the ceiling. Also, the interconnect isn't working. When I test any smoke detector, only that beeps and - none of the others.

I need to ensure that they are all still mains powered and restore the interconnection between them. They have a 3 core and earth cable for the interconnect.

I am pretty handy with electrics and own various tools including a fluke 2 pole tester.

I have 8 detectors. Can you please suggest a logical approach for this. Does the indicator on the detectors have any significance?

Look forward to receiving your advice. Thanks in advance.

 

[Mikegh]

So "recommended", not "mandatory". But I'd not user user-replacable batteries anyhow - to tenants they are either a nuisance that can be silenced by removing the battery, or a handy spare battery for something else ?

Can you silence them by removing the battery alone , don't think so ?

What they will do is slide off the whole lot and take out the battery

 

[brianmoooore]

Aico 141 and 146 smoke alarms will be silenced if you remove them from their base. This disconnects both the mains supply and the battery.
If the alarm is refitted without the battery it will still do what it's designed for, but will emit an annoying single bleep every couple of minutes, the same as with a failing battery.
Most common cause of removed Aico 146 alarms is false sounding because of dust in the optical chamber.

 

[Mikegh]

Aico 141 and 146 smoke alarms will be silenced if you remove them from their base. This disconnects both the mains supply and the battery.
If the alarm is refitted without the battery it will still do what it's designed for, but will emit an annoying single bleep every couple of minutes, the same as with a failing battery.
Most common cause of removed Aico 146 alarms is false sounding because of dust in the optical chamber

They're supplied with battery connected ,so stands to reason you can just whip off the head to silence it , if im getting it right

Was assuming first you'd also have to remove alkaline battery, I should probably remember

 

[Neptune]

They're supplied with battery connected ,so stands to reason you can just whip off the head to silence it , if im getting it right
Was assuming first you'd also have to remove alkaline battery, I should

 

[Neptune]

UPDATE: I created a test rig with two new smoke alarms. I connected them together using 3 core and earth - on the ground (powered by 9v battery) and as expected, the interconnect works with them. I then removed one of the new heads from this set-up and replaced it with each of the 8 heads currently in the house. I tested each of them in both directions: tested the new alarm and the head from the house. None of them apart from one provided the interconnect. They all worked independently. I concluded that 7 of the detectors were faulty.

I purchased 7 new alarms, popped them on one device after the other whilst testing them. They all work!
I did inspect the wiring on each detector and it seemed fine.

I did notice that one of the bases had a burn mark. I replaced this base but with all other detectors, I retained the old bases and slid on the new heads.


All the faulty detectors had a "Replace By" date of June 2026.


I have written to Aico to see if they can cover any of the cost but unfortunately, I don't have receipts for the old detectors.

Here are some images of the call point:

I am questioning whether there is any benefit in having a key for this as it's just as easy to test the system from any of the detectors.

Interested in your thoughts on the above and also, what may have caused the issue which led to all the interconnects failing. Since I have not changed anything other than fitting the new heads, could the underlying issue still be there? Also, is there any reason to retain or fit the bases that came with the new detectors? I left the old bases apart from the one that had a burn mark.

Can I also take this opportunity to thanks everyone for their help and advice.

 

[Simon47]

On a system that size you really need a test switch - otherwise if there's an alarm, you'll be chasing round trying to find the one that's triggered, while being deafened by the racket. With the test switch, you can press the locate switch and all but the one that triggered will turn off.

And of course, if it's rented then tenants (even ones you thought were good ones) will be quite ready to remove what they consider to be "faulty" alarm heads. And since they probably aren't familiar with the little details, they might not use the slot to release the slide lock - so next time you do an inspection you find that the base is broken as well as the head missing. Guess how I know that ?

 

[Yozza19]

On a system that size you really need a test switch - otherwise if there's an alarm, you'll be chasing round trying to find the one that's triggered, while being deafened by the racket. With the test switch, you can press the locate switch and all but the one that triggered will turn off.

And of course, if it's rented then tenants (even ones you thought were good ones) will be quite ready to remove what they consider to be "faulty" alarm heads. And since they probably aren't familiar with the little details, they might not use the slot to release the slide lock - so next time you do an inspection you find that the base is broken as well as the head missing. Guess how I know that ?

I’m pritty sure the locate function only works if it is a rf system

 

[nicebutdim]

I’m pritty sure the locate function only works if it is a rf system

Locate function works on hardwired systems.

 

[Simon47]

You can mix and match with the Aico stuff. In our rental flat we have one sensor and the switch wired, two more sensors wired, and radio modules in two sensors to bridge the two wired segments.
Operting the test switch makes its hardwired head sound immediately - then a couple of seconds later the other two heads sound.

What you don't get on a wired setup (but do with radio) is having all the sensors sound according to the function that triggered. E.g. a Heat & CO head will make different sounds depending on what triggered it. In a radio linked setup, all the other heads will copy that. But with wired interlink they just do their default sound.

 

[Neptune]

so next time you do an inspection you find that the base is broken as well as the head missing

Will keep the spare bases for this reason alone!

 

[Neptune]

Intrigued to hear about possible causes for the IC failure on all but 1 of the detectors. Also, the new detectors are on the same wiring and currently working.

 

[Mikegh]

Intrigued to hear about possible causes for the IC failure on all but 1 of the detectors. Also, the new detectors are on the same wiring and currently working.

Not really following the thread but I've seen interconnect failure a couple of times

Caused it once myself by crossing the wiring and blew the heads , lesson learned

Have also seen it in an installation i was working in, wired but not working

 

[brianmoooore]

Near the beginning of this thread is a pic of the wiring to a head, showing that the wiring colour conventionally used for the interconnect and the neutral have been swapped around. I suspect that at some point a damaged base has been replaced by an electrician who connected the new one conventionally before realising his mistake after powering up. Corrected his wiring, and then walked swiftly away.

 

[Neptune]

But wouldn't that have blown all the IC's? Surprised that one of the device was okay and also the new devices are fine. Why have they not immediately blown?

 

[brianmoooore]

The one good one is probably the one that was being replaced, and hadn't been slid in place when the damage occurred, or it was the first base which has T&E and 3&E.