What is this switch for?

DPR87

Hi all

I have a random switch in my living room. It has a fuse and a small switch next to it.
Behind that wall is the porch - nothing electrical there.
Above it is the main bedroom. 
I have attached a pic if anyone has seen one before.

Thanks

Rosa_Damascena

Give us a clue. Location? (Room and site, not postcode).

DPR87

Rosa_Damascena said:

Give us a clue. Location? (Room and site, not postcode).

Morning
Its in the living room near the ceiling. 
Between the door to enter the living room from the porch and front window. 

Rosa_Damascena

Might there have been an alarm fitted there before?

maisie_cat

Is there a bathroom above? looks like an isolating switch for an extractor or cooker hood

Jeepers_Creepers

Its high-up location is interesting. Is there an outside light, perhaps a PIR type? Does it isolate this?

Do you have an outside shed or garage with just lighting in it?

How DIY competent are you? Can you wield a mains tester screwdriver without killing yourself? If so, turn it off, pop out the fuse, turn it back on and stick yer 'driver in to touch each fuse terminal in turn. Does it light up?

If 'yes', then go to your CU and turn off each 'socket' MCB in turn until this goes deed. If it doesn't, then ditto with each lighting circuit.

If you find an MCB that isolates it, see if there's any description on the MCB label that helps.

GDB2222

It’s currently switched on. What stops working if you switch it off? If nothing changes, it may be a bit of redundant wiring. Possibly live, or possibly not even part of the circuit any longer.

ic

Is there even a fuse in it?  If not, you know its a dead end.  Agree its probably to do with exterior lighting, or something close by in the room above.

DPR87

Thanks for all the replies - some answers below

- No wired alarm (nothing to indicate there has been previously) - currently using a wireless one
- There is an ensuite above (not directly more to the left). There is a separate isolating switch for the fan upstairs
- We've turned it off - nothing obvious has happened yet (garage lighting still works fine)
- There is no other exterior lighting 

I'll get up there check re: the fuse (as per Jeepers and ic). Sprained ankle at the moment so I'll give it a go in a few days.

Thanks again