Stairwell lighting went off, needing advice

securespark · Tuesday at 9:25 PM

Have worked on those Royce Thompson units before.
That one looks a bit roughly installed though...

Not sure what the white cable is doing.

pete01 · Tuesday at 9:27 PM

Must go out to the photocell as Adrian said?

pete01 · Tuesday at 9:34 PM

What's the point of these Royce Thompson gadgets? Just make your own with a box and a switch, No?

AdrianUK · Tuesday at 9:38 PM

pete01 said:
What's the point of these Royce Thompson gadgets? Just make your own with a box and a switch, No?

Noooooooo...... there is a thermal relay inside...... kinda like the pre-empting heater in a room thermostat... its gives the photcell an in built 'delay' and hysteresis so it switches cleanly.

pete01 · Tuesday at 9:39 PM

AdrianUK said:
Noooooooo...... there is a thermal relay inside...... kinda like the pre-empting heater in a room thermostat... its gives the photcell an in built 'delay' and hysteresis so it switches cleanly.

Oooohhhh ok, I knew that

SUNRAY · Tuesday at 9:47 PM

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

That's a standard red spot BS88 fuse holder, used to be THE fuseholder used in control panels.

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

The route of live is I believe:
In from cut out bottom right - meter - red spot fuse - Royce unit, teed to - T&E

So I'll assume the door entry system is on the end of that ask if it's working before checking the photo sensor?

I assume the 3 sets reds and blacks feed the three flats.

endecotp · Tuesday at 9:58 PM

garnet said:
This el meter is only for the stairs' lights and the intercom.

Does the intercom work?

garnet · Tuesday at 10:40 PM

Hi all,
All is very strange.
the gray cable on the top of the meter goes to intercom electronics. They work OK.
I dont see where the cables go so they can supply the lights, but I guess lights wont be supplied through the intercom electronics.

The BS88 fuse was blown. I did change it, it works now.
White cable comes from photocell outside.
Switching to test still does not turn the lights on.
I am still not sure about the copper "pipe" switch, what its' role is.

Harry Bloomfield · Tuesday at 10:49 PM

SUNRAY said:
That's a standard red spot BS88 fuse holder, used to be THE fuseholder used in control panels.

Yes, they push in, then slide up to lock into place. Strange use for such a fuse-holder - I wonder if the meter, is a privately owned meter, tapped into one of the flat supplies, then the freeholder was supposed to reimburse the cost of the used units, back to the flat owner?

garnet · Tuesday at 11:06 PM

Harry Bloomfield said:
Yes, they push in, then slide up to lock into place. Strange use for such a fuse-holder - I wonder if the meter, is a privately owned meter, tapped into one of the flat supplies, then the freeholder was supposed to reimburse the cost of the used units, back to the flat owner?

I dont know if it privatelly owned, but there is a separate live cable coming from the ground to it.
So I guess it is Energy supplier's - or the council - this used to be council building.

endecotp · Tuesday at 11:13 PM

garnet said:
I dont see where the cables go so they can supply the lights

garnet said:
I am still not sure about the copper "pipe" switch, what its' role is.

That’s surely the lights.

Is there another fuse inside the MEM switch box?

SUNRAY · 2025-12-10T00:03:10+0000

Harry Bloomfield said:
Yes, they push in, then slide up to lock into place. Strange use for such a fuse-holder -

It looks to me to be the type that just pulls out but it matters not. I would have expected to see something more like the MEM switched fuse

Harry Bloomfield said:
I wonder if the meter, is a privately owned meter, tapped into one of the flat supplies, then the freeholder was supposed to reimburse the cost of the used units, back to the flat owner?

garnet said:
I dont know if it privatelly owned, but there is a separate live cable coming from the ground to it.
So I guess it is Energy supplier's - or the council - this used to be council building.

I assumed below to the right is a 3 phase company fuse feeding the 3 red cables running horizontally and then down into conduits (but this is all sopposition). It appears to be an official meter with an official coded seal so I assume its a standard energy suppliers meter with a standing charge. Another picture of that area would be likely to confirm that but it's unlikely to make any difference to the lighting fault.

garnet said:
Hi all,
All is very strange.
the gray cable on the top of the meter goes to intercom electronics. They work OK.

So you have power

garnet said:
I dont see where the cables go so they can supply the lights, but I guess lights wont be supplied through the intercom electronics.

No

garnet said:
The BS88 fuse was blown. I did change it, it works now.

garnet said:
White cable comes from photocell outside.

Yes it's a standard arrangement

garnet said:
Switching to test still does not turn the lights on.
I am still not sure about the copper "pipe" switch, what its' role is.

I assume the 'copper pipe' is the outgoing cable (MICC - Mineral Insulated Copper Cable) which heads out to all of the lights. As endecotp says the grey MEM box is a switched fuse, check to see if thats blown too.

garnet · 2025-12-10T10:22:43+0000

endecotp said:
That’s surely the lights.

Is there another fuse inside the MEM switch box?

I will check that.

garnet · 2025-12-10T15:28:01+0000

This is getting even more weird.
I opened the MEM switch. There is a 20A fuse in there. Also blown. Will rewire it.
In the meantime I connected the terminals of the mem switch fuse with a bridge wire and set the photocell to test. Still no lighting. I can see current to the upper terminal of the mem switch from where a black cable runs in the copper pipe to the lights.
I am at a loss here.
How can both fuses be blown, one 16A should have been blown and that is it. How the 20A got blown? And if they can both be blown, can anything else on the circuit be fried also? The cable itself?
The problem started after a very weird event. It was very cold here for a week - 0C. The stairwell is external so all the walls were at 0C. All of a sudden temperature went to 13C in a day, and it was very humid. I saw so much water condensed on the walls and ceiling that it was dripping on the floor. So my theory is that it might have gone to the light fixture connection terminals. Not sure what's going on.

Harry Bloomfield · 2025-12-10T19:21:38+0000

garnet said:
I can see current to the upper terminal of the mem switch from where a black cable runs in the copper pipe to the lights.

How are you 'seeing the current'?

My earlier assumption was wrong about that black fuse carrier - it is preceded by a company, cut-out fuse. It goes -
cut-out, black fuse, MEM fuse, then to the lights.

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Stairwell lighting went off, needing advice

securespark

pete01

pete01

AdrianUK

pete01

SUNRAY

endecotp

garnet

Harry Bloomfield

garnet

endecotp

SUNRAY

garnet

garnet

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