Mains smoke detectors

[Nijinski001]

The instructions on my mains smoke detectors aren't clear.

I don't normally fit these but I am fitting three smoke detectors, one on each floor of a back to back terrace.

There are three wires. Brown, Blue and White. I understand the mains supply goes to brown and blue as you would expect. As per the instructions the white is the link between detectors to ensure that if one goes off they all go off.

Should the wiring be as follows? Twin/Earth from mains supply to the first detector and then 3 Core/earth to the next two daisy chained?
It also says a dedicated power supply should be provided. This obviously indicates a radial circuit on a separate MCB which I assume should be 6A?
Am I right in assuming some people have wired smoke detectors from the lighting circuit in the past? Have the regs changed recently and if so can someone point me to the correct reg?

Cheers

 

[Steve]

someone posted something a few days ago. If the alarms have battery backup they can run on the light circuit. If no batteries, must be on their own circuit (6A MCB)

 

[plugwash]

if the alarms have battery backup then they can be connected to a local lighting cuircuit.

the trouble is this makes interconnection awkward (since few houses have all thier lighitng on one cuircuit) so in reality people normally put them on a dedicated cuircuit.

 

[Nijinski001]

Thanks guys.
Am I right with the assumption though that there is no power required into the white wire. It is purely a connection point?

 

[Spark123]

Thanks guys.
Am I right with the assumption though that there is no power required into the white wire. It is purely a connection point?

Yes