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Interlinking different brands of smoke alarms


 
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Donkmeister

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PostPosted: Wed Sep 09, 2009 8:33 pm Reply with quote

A bit of information you may or may not be aware of, but it would seem that interlinking different brands of smoke alarm may not work correctly.

I'm planning to add in some interlinked mains-supplied battery backed-up smoke/heat/CO detectors. So, I went to the Kidde website to look at a few and found the following in the FAQ:

Quote:
Q) Can I interconnect my hard wired Kidde units with other brands?
A) It is not advisable to do this because other manufacturing companies may use a different temporal pattern ( temporal pattern means how the voltage is sent over the interconnect white wire that tells the other units to go off as the originating smoke alarm has sensed some smoke).


Which seems a bit stupid, but that's the situation.

So, if you are adding to an existing system or replacing the odd failed unit, you should probably aim to replace like with like.

Does anyone here have any experience of Kidde's domestic products? Any good?

I'm looking to put a CO alarm and heat alarm in the kitchen (the only room in my house with gas appliances), optical alarms in the bedrooms and ionisation alarms in the hallways and living room. I am planning on having a fireplace in the living room reinstated at a later stage to burn wood and/or coal... would ionisation be the correct choice?
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Taylortwocities

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PostPosted: Wed Sep 09, 2009 11:15 pm Reply with quote

This link tells you about the two types of alarm and which to fit and where. In summary, it says fit both (mind you, they do make them)! clickme.

Kidde is a decent make.

You cannot interconnect different makes of alarm, they have different signalling. Buy one of the same make and don't mess around. Smoke alarms provide a degree of safety - only fit and use them in accordance with the maker's instructions.

PS AICO recommend that you do not interconnect CO and smoke alarms as the actions to be taken in the event of FIRE are different to the action you would take for a CO leak.
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ban-all-sheds

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PostPosted: Thu Sep 10, 2009 10:29 am Reply with quote

Donkmeister wrote:
A bit of information you may or may not be aware of, but it would seem that interlinking different brands of smoke alarm may not work correctly.

I would never in a million years have thought it would work.


Quote:
Which seems a bit stupid, but that's the situation.

It seems perfectly reasonable, understandable and to be expected. It seems a bit stupid to expect otherwise.
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Donkmeister

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PostPosted: Thu Sep 10, 2009 10:40 pm Reply with quote

ban-all-sheds wrote:

It seems perfectly reasonable, understandable and to be expected. It seems a bit stupid to expect otherwise.


Your opinion of course, but from an engineering point of view this is poor practice, from a safety point of view it is foolhardy. Smoke alarms of different brands are:

1) constructed to perform the same function
2) constructed with the same physical interface
3) designed to be utilised with the same cabling
4) certified against the same standards, which are embossed on the exterior.

Whilst it would take a leap of stupidity or incompetence to connect a 3-core and earth from a dimmer switch to a smoke alarm (same physical interface and cabling), it is not unreasonable to expect one smoke alarm to be interchangeable with another of the same fit, form and function, with the same standards nos. written all over it.

Speaking as an engineer, I would say that the standardisation bodies have missed a trick here. A standardised signalling scheme would eliminate the risk of someone replacing a non-functioning alarm with a functional alarm that will not interpret the interlink signal sent by one of the other alarms.

If you still think it is stupid, consider this: what if Kidde decided that from 1st January 2010, all its new interlink alarms would have a completely different signal definition? The absence of a standard means there is nothing to stop them doing this, and they are under no obligation to put stickers all over the box saying "only interface this with other new Kidde alarms!!!". icon_eek.gif
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Donkmeister

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PostPosted: Thu Sep 10, 2009 10:51 pm Reply with quote

Taylortwocities wrote:

PS AICO recommend that you do not interconnect CO and smoke alarms as the actions to be taken in the event of FIRE are different to the action you would take for a CO leak.


I'll look into that, I just assumed that interlinking everything would be the best course of action i.e. it wakes me up, I leave the house and assess the situation. I'm a very heavy sleeper so would need a sounder in my bedroom (I have slept through fire drills in the past).

Kidde do ones with a display that says "FIRE" or "CO", perhaps I'll go for those ones.
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Taylortwocities

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PostPosted: Thu Sep 10, 2009 10:59 pm Reply with quote

The link to the AICO advice is clicky check out page 9

It says
"There is merit in interconnecting CO and smoke/heat alarm
systems, as it will improve audibility throughout the property
However, it is generally considered that interconnecting CO
alarms into a smoke/heat alarm system is not good practice, as
the actions that should be taken in the different emergencies
are quite unique:
If a fire occurs, you should keep doors and windows closed to
contain the fire as much as possible.
If a CO leak occurs, you should open all doors and windows
to ventilate the area as much as possible - at the same time
turning off the appliance/s from where CO leak is being
emitted.
We believe that interconnection between the 2 types of systems
may be considered if the user is able to determine which of the
alarms has caused the system to operate (the smoke alarm or
the CO alarm) so enabling them to make the correct decision
on what action should be taken. The only foolproof method of
achieving this is by having a means of silencing the remaining
system i.e the alarms not actually sensing smoke or CO. The
solution to this problem would be the addition of an Ei1529RC
Alarm Control Switch into the system.."
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Donkmeister

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PostPosted: Thu Sep 10, 2009 11:10 pm Reply with quote

Excellent, thanks again. I've seen those alarm switches, I would suppose the safest place to put one is just inside the front door.

Not sure I would want to sit squinting at an LED display on the ceiling anyway... if I was woken by the alarm at night, far more important to get out asap!
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bernardgreen

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PostPosted: Fri Sep 11, 2009 6:45 am Reply with quote

I think that irrespective of it being a smoke alarm or CO alarm the prime objective is to get the family OUT of the house away from the danger and into fresh air.

If a person is found to be un-conscious or un-wakable in a room with no smoke then one can assume it is CO and act accordingly which still has the prime objective to get them out into fresh air.

How many people fit smoke alarms but never practise an evacuation of the house in the dark. ( which is easy compared to a sudden evacuation when dis-orientated by smoke and fear )
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ban-all-sheds

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PostPosted: Fri Sep 11, 2009 11:06 am Reply with quote

Donkmeister wrote:
ban-all-sheds wrote:

It seems perfectly reasonable, understandable and to be expected. It seems a bit stupid to expect otherwise.


Your opinion of course, but from an engineering point of view this is poor practice,

I agree that the industry has displayed very poor practice in not developing a de facto standard for interconnections, or pressing for a de jure one.


Quote:
from a safety point of view it is foolhardy.

What is foolhardy is to simply assume that different makes of detectors can be interconnected without checking first.


Quote:
4) certified against the same standards, which are embossed on the exterior.

It is also foolhardy to assume that a standard covers what you think it should, rather than checking that it does, if it's important to you.


Quote:
it is not unreasonable to expect one smoke alarm to be interchangeable with another of the same fit, form and function, with the same standards nos. written all over it.

Your opinion of course, but from a common sense point of view this is poor practice.


Quote:
Speaking as an engineer, I would say that the standardisation bodies have missed a trick here. A standardised signalling scheme would eliminate the risk of someone replacing a non-functioning alarm with a functional alarm that will not interpret the interlink signal sent by one of the other alarms.

They have, and it would, but as an engineer you should know better than to assume that they haven't.


Quote:
If you still think it is stupid, consider this: what if Kidde decided that from 1st January 2010, all its new interlink alarms would have a completely different signal definition? The absence of a standard means there is nothing to stop them doing this, and they are under no obligation to put stickers all over the box saying "only interface this with other new Kidde alarms!!!". icon_eek.gif

I'm sure they would be obliged to make that fact known in the installation instructions.
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