upstairs lights and alarm on same circuit

[MoonMan2]

I switched off MCB in fuse box (for upstairs lights) to replace bedroom light switch with dimmer switch. Upstairs I then removed light switch and noticed there was two sets of wires going through one light switch. I don't think this is compatiable with the dimmer switch so I left things as they were.

When I switched MCB for upstairs lights back on the alarm went off. I realised that the upstairs lights and alarm are on the same circuit.

Will this cause me any problems?

 

[jj4091]

No

 

[1john]

you have a dead battery on your alarm. the wiring in the switch, were two of the wire in a connector block and the other two into the switch, was the back box earthed??