wired fire alarms

[SparkyTris]

Anyone know how does the interlink system work on wired mains-powered domestic smoke & heat heads?

if so, please might they explain?

I mean, I know that they use a separate conductor for the link, but what signaling is applied to this line by an initiating head to ensure that all the other connected heads alarm?

 

[DetlefSchmitz]

I do not know the answer, but I think you have to assume it is a proprietary system, which may differ between vendors.

 

[Echo the husky]

I don't know but on the AICO alarms if you short the interlink and neutral together they beep.

I believe the proper operation is more technical than that though.

 

[AndyPRK]

Beep but not alarm ?

 

[Echo the husky]

By beep I mean alarm

 

[ban-all-sheds]

Anyone know how does the interlink system work on wired mains-powered domestic smoke & heat heads?

if so, please might they explain?

I mean, I know that they use a separate conductor for the link, but what signaling is applied to this line by an initiating head to ensure that all the other connected heads alarm?

Why do you want to know?

Just curiosity, and a desire to learn (fine)?

Or because you want to use the signal for something else, or interfere with it in some way (not fine)?

 

[Taylortwocities]

Why do you want to know?

Yes, why? If you, perhaps, want to operate something else when the alarm is triggered, then some manufacturers provide devices that allow you to trigger the alarm from an external source (a sprinkler system, for instance),
example AICO Ei129 Switched Input Module
or for the alarm to provide a relay closure when the alarm is triggered to operate external devices
example AICO Ei128R Relay base

 

[SparkyTris]

It's to provide an auxiliary closure to operate an autodialer.
The Kidde system appears to float the line in normality and then swings to +9Vdc in alarm condition.
I wondered exactly how "proprietary" the interconnect might be across different manufacturers, mainly out of interest.
My kidde heads will bleep an error if the interconnect line is held low which I guess is a nice feature

 

[Taylortwocities]

Your best option

CLICK ME

 

[oldbutnotdead]

You really don't want to be connecting random stuff to hardwired alarm cables. Modern systems will be using some sort of multiplexing on the signal line (to report back to the panel that detector is present and working and what type of detector it is)- all using the same basic techniques but mainly designed so that only their detectors will work on their alarm system
If there isn't a volt-free pair of contacts in the panel for an autodiialler there'll be an add-on card you can buy to connect one.
Be very aware of how much liability could attach to you if you start messing about with such systems

 

[JohnW2]

You really don't want to be connecting random stuff to hardwired alarm cables. Modern systems will be using some sort of multiplexing on the signal line (to report back to the panel that detector is present and working and what type of detector it is)- all using the same basic techniques but mainly designed so that only their detectors will work on their alarm system. If there isn't a volt-free pair of contacts in the panel for an autodiialler there'll be an add-on card you can buy to connect one.

Indeed. The majority of domestic fire/smoke alarm detectors don't have 'a panel' but, as TTC has pointed out, most (possibly all) manufacturers of interlinked detectors off some sort of relay module which can be connected to them

Be very aware of how much liability could attach to you if you start messing about with such systems

Whilst the above had to be the correct and sensible advice, the reality is that someone with adequate (electronic) knowledge could easily devise a system of interfacing with the alarms which involved virtually no risk (and see ** below for 'literally no risk')) of impairing the proper functioning of the alarm system. As for potential liabilities (and effects on insurance etc.) that presumably depends upon the situation - in a situation in which having alarms at all is not 'compulsory', any liabilities associated with having ones which have been rendered inoperative by 'tampering' are presumably no greater/worse than one would be the case if one had no alarms at all?

** Although I would say that I personally do have enough 'electronic knowledge' to have been able to achieve that 'virtually no risk' situation, what I did in a similar situation literally involves no risk (to the existing alarm system). The alarms are so loud and persistent (compared with any other sound one could credibly expect in a house) that one can easily engineer a sound-triggered system with a small microphone close to one of the alarms - and that's what I did (and, in many years, there has never been triggering by any 'extraneous sounds')!

Kind Regards, John

 

[ban-all-sheds]

in a situation in which having alarms at all is not 'compulsory', any liabilities associated with having ones which have been rendered inoperative by 'tampering' are presumably no greater/worse than one would be the case if one had no alarms at all?

Except that if the people living there think that the alarms are working properly then you shouldn't render them inoperative. I would not be surprised, even if having them was not a condition of contents insurance, if a claim for fire damage ran into problems because the damage was worse than it "should" have been because someone had tampered with the alarms.

 

[flameport]

I wondered exactly how "proprietary" the interconnect might be across different manufacturers, mainly out of interest.

Entirely different and incompatible.

The Aico ones are not just 'alarm' or 'normal' either, as they make various other devices such as a switch module which can be used to test the alarms, silence them if sounding and locate the particular one which caused the alarm.

 

[JohnW2]

I would not be surprised if any insurance claim "ran into problems" because of any number of issues/factors, only some of which I would personally regard as 'reasonable' (rather than 'wriggling'!).

 

[ban-all-sheds]

Quite.

So best to avoid creating any more issues.