On 19/09/10 14:48, Lee Nowell wrote:
Hi All,

We have a burglar alarm with a couple of spare "zones".
Unfortunately, when we had our fire alarms fitted (mains powered and
all interlinked), I didn't think about integrating them with the
burglar alarm so we will be notified if the fire alarm goes off whilst
we are out of the house.

I was wondering, if I put a relay in, would I be able to connect the 2
together such that the burglar alarm treats it like any other zone in
the house.

My logic (which may well be flawed!) is as follows....
- connect the 240v interconnect from one of the smoke alarms to one
side of the relay (I have assumed that the interconnect goes "live"
when the fire alarm goes off - is this true or is it a switch?)
- connect the 12v alarm wire to the other side such that the relay
opens the switch when it gets 240v the other side (i.e. breaks the
alarm feed and sets the alarm off).

I'm sure it is not really this easy ..... and would greatly appreciate
any help you folks can give me.

thanks

Lee.

I have a strong feeling that the "interconnect" may be more than a
simple on/off signal in many cases and that it will be manufacturer
dependent.

Mine (Kidde) can support a manual intervention switch on the interlink
that allows testing *and* silencing of all alarms.

There are also warnings of not running the interlink cable closed to
dimming circuits which suggests a more complex signal.

The Kidde ones do have an optional extra:

http://www.tlc-direct.co.uk/Products/KDSMK23R.html

for doing what you want.

HTH

Tim