I want to run a new cable from my consumer unit to pick up 2 CO alarm
and 4 smoke alarms:
Is a 1.5mm cable from a spare 16A MCB okay? Does the cable need to run from alarm to alarm (i.e. radial) or can run a single cable to the furthest one and spur off at 4 points for th other? (the later would use much less cable) If I did the latter, would it cause problems
-- Cordless Crazy
I think a 16A MCB is a bit high - 6A should do it. The alarms *must* all be the same brand with a single T&E from the CU to the first one then 3-core&E to the next and so on in a radial-type circuit. Have a look at:
John.
Yes.
It is normal for the smoke alarms to need a 3&E interconnect. You normally achieve this by running the main supply to the nearest alarm. The other alarms are then connected to each other from the first one using the 3 core cable (such as that intended for 2 way lighting circuits), which usually consists of a live, neutral and signal core (plus the earth, of course). You can run the cable in any manner that is convenient, whether star or daisy chained. If the alarms genuinely use 2 cores of the interconnect as live and neutral, then the initial (T&E) supply line can go straight to a star topography junction box.
If the alarms are of different brands, then the interconnect probably won't work/will destroy the alarms. You should take them back/discard them and buy same branded linked alarms from a single manufacturer.
Christian.
Make it a 6A MCB and no problems, however 16A is a) far above what is required for smoke alarms, and b) unlikely to be sufficient protection for a 1.5mm circuit.
Whoops. Yes, I didn't notice the oversized MCB.
Christian.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required