MR11 3.5mm Spots stopped working

SLOPPY · Jul 2, 2023

Hi all. I'm new to this forum so thank you for having me.

I'm having an issue with my bathroom lights. I have x4 MR11 3.5mm Spots. They've been up about 8 years without ever having to change a bulb. They are operated from a 2 switch cover outside the bathroom, one for the lights and the other switch for the fan, the fan is working fine.

Not sure if this is a coincidence, I have a razor socket inside the bathroom which I used for the very first time a few days back having received an electric toothbrush. Since using it, my lights stopped working.

I have replaced all the bulbs with new LED MR11 bulbs and unfortunately they still don't work.

Ive also removed the light switch cover and razor cover the check for loose wires, everything seems fine.

My expertise is wiring a plug only hence I've arrived here.

I would appreciate any advice before I call out an electrician.

Many thanks in advance.

plugsandsparks · Jul 2, 2023

Somewhere, probably hiding in the ceiling will be the 12V transformer(s), good luck finding it/them

P&S

mainline · Jul 2, 2023

SLOPPY said:
Hi all. I'm new to this forum so thank you for having me.

I'm having an issue with my bathroom lights. I have x4 MR11 3.5mm Spots. They've been up about 8 years without ever having to change a bulb. They are operated from a 2 switch cover outside the bathroom, one for the lights and the other switch for the fan, the fan is working fine.

Not sure if this is a coincidence, I have a razor socket inside the bathroom which I used for the very first time a few days back having received an electric toothbrush. Since using it, my lights stopped working.

I have replaced all the bulbs with new LED MR11 bulbs and unfortunately they still don't work.

Ive also removed the light switch cover and razor cover the check for loose wires, everything seems fine.

My expertise is wiring a plug only hence I've arrived here.

I would appreciate any advice before I call out an electrician.

Many thanks in advance.

Is the shaver socket still working ?
Are all the other lights working ?
Is anything tripped in the consumer unit ?

SLOPPY · Jul 2, 2023

mainline said:
Is the shaver socket still working ?
Are all the other lights working ?
Is anything tripped in the consumer unit ?

All 4 lights are not working in the bathroom, however all the upstairs lights are working fine.
The shaver socket is still charging my toothbrush.
Nothing is tripped on the consumer unit.
Thanks for your reply much appreciated.

mainline · Jul 2, 2023

SLOPPY said:
All 4 lights are not working in the bathroom, however all the upstairs lights are working fine.
The shaver socket is still charging my toothbrush.
Nothing is tripped on the consumer unit.
Thanks for your reply much appreciated.

You really need to have a meter to check supplies.
It could be anything from a failed switch or a bad joint.
It's highly unlikely to be 4 failed transformers /lamps.

SLOPPY · Jul 2, 2023

mainline said:
You really need to have a meter to check supplies.
It could be anything from a failed switch or a bad joint.
It's highly unlikely to be 4 failed transformers /lamps.

I have an electrical pen the lights up when you touch inside a socket.
Would you recommend I unsrew the double light switch and touch the connected wires individualy with the pen while the swith is in the on position.
Forgive me, I'm sure there must be an official name for the tester pen.

Update - it says its non contact voltage detector. It seems to work without unscrewing the switch fitting. I turn the pen on and it flashes red on both when I touch the switches.

mainline · Jul 2, 2023

SLOPPY said:
I have an electrical pen the lights up when you touch inside a socket.
Would you recommend I unsrew the double light switch and touch the connected wires individualy with the pen while the swith is in the on position.
Forgive me, I'm sure there must be an official name for the tester pen.

Update - it says its non contact voltage detector. It seems to work without unscrewing the switch fitting. I turn the pen on and it flashes red on both when I touch the switches.

A non contact pen isn't a very reliable way of testing, It could be that you have a loss of the neutral.

DPG · Jul 2, 2023

You need to find out if the transformer has packed up.

SLOPPY · Jul 2, 2023

mainline said:
A non contact pen isn't a very reliable way of testing, It could be that you have a loss of the neutral.

OK it looks like I'll have to get a professional in.
Many thanks for trying to help me it's very much appreciated.

SLOPPY · Jul 2, 2023

DPG said:
You need to find out if the transformer has packed up.

Its a bit beyond me locating a transformer. I'll phone up a professional.
Many thanks for your time much appreciated.

I'll post back with the outcome.

SLOPPY · Jul 10, 2023

DPG said:
You need to find out if the transformer has packed up.

I've got a little bit further.

I've found the transformer (in picture)
The lights are on a chain of 4.
When I touch with my non contact voltage detector, the mains wire into the transformer, the output cable from the transformer, and all 4 wires going into each bulb voltage pen lights up suggesting there's power.

Do you think I still need to replace the transformer?

Many thanks in advance.

Avo Mk8 · Jul 10, 2023

SLOPPY said:
I've got a little bit further.

I've found the transformer (in picture)
The lights are on a chain of 4.
When I touch with my non contact voltage detector, the mains wire into the transformer, the output cable from the transformer, and all 4 wires going into each bulb voltage pen lights up suggesting there's power.

Do you think I still need to replace the transformer?

Many thanks in advance.

Reading what's written on the transformer, it seems to me likely that your new led bulbs do not add up to the minimum load that the transformer needs, namely 35watts. It's an electronic "transformer" specifically for halogen bulbs, so I think your choice is either to replace the bulbs with the halogen type, or buy a new 12V transformer suitable for driving your four LED bulbs.
But you really need a better method of testing than a volt stick, or someone to check this out for you. A multimeter would give a much better indication of what's going on, but in the meantime you could try replacing one led bulb with a halogen type and see if it all springs back to life!
The fact that your pen tester lights up on the wires going to the bulbs (from the SELV transformer) does possibly suggest a lost neutral to the supply? as has been mentioned before.

SLOPPY · Jul 10, 2023

Avo Mk8 said:
Reading what's written on the transformer, it seems to me likely that your new led bulbs do not add up to the minimum load that the transformer needs, namely 35watts. It's an electronic "transformer" specifically for halogen bulbs, so I think your choice is either to replace the bulbs with the halogen type, or buy a new 12V transformer suitable for driving your four LED bulbs.
But you really need a better method of testing than a volt stick, or someone to check this out for you. A multimeter would give a much better indication of what's going on, but in the meantime you could try replacing one led bulb with a halogen type and see if it all springs back to life!
The fact that your pen tester lights up on the wires going to the bulbs (from the SELV transformer) does possibly suggest a lost neutral to the supply? as has been mentioned before.

I've now ordered a new transformer suitable for LEDs and some halogen bulbs just to test on the current transformer. They arrive tomorrow.

'Lost neutral' sounds interesting, but much beyond my minimal knowledge which amounts to wiring a plug and maybe a light fitting change.

I'll try the new halogen bulbs first, if no success, I'll swap the transformer to the new LED one using the LED bulbs.

If that doesn't work, like you say it's probably a lost neutral. In that situation I'll have to call in a professional.

I'm bit frustrated as I've taken the floating ceiling down and I didn't want this to beat me lol

I'll update on here tomorrow.

Thanks for your detailed reply. Very much appreciated.

Avo Mk8 · Jul 10, 2023

SLOPPY said:
'Lost neutral' sounds interesting,

It's just jargon meaning the blue (or black if old wiring!) neutral wire has become disconnected somewhere on its way from the supply to the transformer in the ceiling

SLOPPY · Jul 11, 2023

Avo Mk8 said:
It's just jargon meaning the blue (or black if old wiring!) neutral wire has become disconnected somewhere on its way from the supply to the transformer in the ceiling

Wohooo they're working.

As I said in my previous post, I tried the new halogen bulbs first, unfortunately that didn't work.

Then I changed the transformer form the halogen transformer to the new LED supported transformer, then fitted the new LED MR11 bulbs and thankfully they worked.

I guess we can conclude that the halogen transformer was defective.

Now I've got the job of putting my floating ceiling back together, a job I learned I didn't need to do, as seen in the picture, it turns out the transformer was hidden above a hole in the original ceiling plasterboard between the loft insulation, I should have lifted that up when I first got in the loft. It's a bit of a chore putting it all back, but I'll do it with the biggest smile on my face.

Thanks to everybody who responded, I could not have done it without your help, I bow to your expertise.
I've leaned a few things, didn't know about transformers and the different types. It was a bit daunting, but it goes to show, you can achieve anything with a bit of patience, confidence and some good advice.

Thanks again very much appreciated.

David

MR11 3.5mm Spots stopped working

SLOPPY

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mainline

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DPG

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