Fused Spur query

[petesrepairs]

I would not put a smoke alarm on a fused spur. If the fuse goes, or it gets switched off then you won't know.
Thats why its better to use a lighting circuit, you'll always notice that if it didn't work.

For your other queries:

Is it allowed to have a fused spur under the floor boards? Or will I have to bring it to a faceplate with access to the fuse into a all mounted back box?
NEVER put a fused spur under the floor, how will you access it if/when the fuse goes!

Should I put in a switched or unswitched spur for the alarm?
Unswitched, but use a lighting circuit
Am I correct in that it should be 2.5mm to the spur and then 1.0mm to the alarm from the fused spur.
Depends on the fuse size, but you'd probably use a 3A fuse, so 1mm is OK, but use the lighting circuit

Hi, I am just a little curious as to how to interpret this section in the on site guide (pg 65 under wiring of smoke and heat alarm) "B be permanently wired with an independent circuit from the distribution board or supplied from a local, regularly used lighting circuit (there should be a means of isolating the supply to the alarms without affecting the lighting)."

Ok, so i know that i need to link it to the lighting circuit, as i cant attach it easily to the distribution board, so connecting it to the lighting circuit is easy enough. But there should be a means of isolating it, so I'm thinking either a normal double pole switch or a switched fused spur, which would you think? Also when it says isolating the supply to the alarms without affecting the lights, I take it that it means being able to disconnect the alarm(s) from the power supply to the lights, or does it mean leaving the alarms permanently live and having a switch to disconnect the lights?

cheers in advance

Pete

 

[houstonwehaveaproblem]

Take a permanenty live mains supply feed from a regularly used lighting ceiling rose using 1.5mm twin and earth cable and wire it to an unswitched fused connection unit fitted adajcent to or nearby the smoke alarm. Fit 3 amp fuse in connection unit.