Stairwell lighting went off, needing advice

[garnet]

Hi all,
this is about a stairwell lighting in one block of flats.
The lights are on a light sensor, which turns them on when it gets dark outside.
About a week ago lights stopped working.
I took a look at the fuse board and found a blown fuse (16A) on the circuit which leads to the light sensor.
I changed the fuse, but lights are still off.
This is all very old building. This is what there is in the fuse box.
This el meter is only for the stairs' lights and the intercom. White cable is connected to the light sensor outside.
I am not sure what the gray switch does, but there is something like a copper pipe going out of it.
Fuse that was blown is just under the el. meter/grey switch.
Any ideas?

 

[AndyPRK]

something has caused the fuse to blow.

Could be the sensor or cable

 

[pete01]

Split the circuit in half and try the fuse again, keep narrowing it down, hopefully it's something simple like a faulty fitting.

How many lights? If only a few check inside each one, see if you can see or smell anything burnt out.

 

[garnet]

4 lights fittings in the building.
Fuse doesn't blow at the moment. I would expect it to blow immediately if something was wrong with the fixtures.

 

[pete01]

Override the sensors, see if the lights come on

 

[pete01]

I am not sure what the gray switch does, but there is something like a copper pipe going out of it.

Thats an MICC cable maybe going to a fire alarm?

 

[Harry Bloomfield]

Thats an MICC cable maybe going to a fire alarm?

What is the unit, with 'auto-test' on it?

 

[pete01]

What is the unit, with 'auto-test' on it?

Not sure, never seen one of those

 

[AdrianUK]

What is the unit, with 'auto-test' on it?

That's a RoyceThompson controller for a two part photocell.

In the days before the 'modern' twist-lock units, there was a separate photocell module that mounted outside & the control box inside (or rather inside the lamp column control box).

If you flick the switch to 'TEST' it will over-ride the cell & the lights should come on

Ask Mr Google about a "RoyceThompson P42"

My guess is that the MEM metalclad switchfuse & the MICC feed the staircase lights. And the white cable goes off to the photocell module.

 

[sparkwright]

What about that in-line fuse, that's floating about?
Is that anything to do with it?

 

[AdrianUK]

What about that in-line fuse, that's floating about?
Is that anything to do with it?

I reckon the meter outlet is the supply, then the inline fuse, then the P42 controller & finally the MEM switchfuse & off to the lights......

 

[Harry Bloomfield]

What about that in-line fuse, that's floating about?
Is that anything to do with it?

It seems to be a cut-out fuse, supplying the meter - I'll bet that blew as well.

 

[AdrianUK]

It seems to be a cut-out fuse, supplying the meter - I'll bet that blew as well.

I think that fuse is on the load side of the meter, but I agree that it may well be popped.

 

[pete01]

So he could switch it to test and if that works maybe a photocell problem?