Downlights not working (with MR16 LED lamps)

[Stewart Birrell]

Hi there,

Some of the downlighters in our kitchen have stopped working, in fact all three in a row have stopped working. It is not the lamps (or bulbs) as I have changed them both for other LED and also Halogen, it is not the burnt out lamp holders as I have changed one and it had no effect. It is not the light switch as although 3 in a row are out, they all run off different switches (and the other lights in the switch row all work). It might be the transformer, but does each lamp have its own transformer, or does one transformer run numerous lamps (and coulf it run all three in row, hence why mine have gone). But the transformer looks quite new and shinny (not the best measure for it being broken I know!).

I didn't want to go buying new transformers until I got some expert advice. Also does anyone have any other ideas as to what could be the problem.

If you need more details or clarity then please ask.

Thanks,

Stewart

 

[oldbutnotdead]

You can get transformers (chunky things full of copper) or power supplies (lightweight switchmode things full of fresh air and gubbins) that will run 1 lamp or 10, depends what wattage the lamps are (yes they vary) and how the job was wired. The switchmode ones in particular are load sensitive- they may stop working if the load is too low (so if your block of 3 lamps are on 1 SM power supply and 1 lamp has blown, the other 2 may fail to illuminate). You say you have many switches and one transformer- implies to me that someone may have wired the switches on the low voltage side.

Do you have a voltmeter? Did you wire the lamps yourself? Can you do a sketch of how the lights are switched (a piece of paper with blobs for the lamps and a number for which switch controls which lamp would do for starters)

 

[ban-all-sheds]

You say you have many switches and one transformer

Does he?

It might be the transformer, but does each lamp have its own transformer, or does one transformer run numerous lamps

 

[ericmark]

It is not the light switch as although 3 in a row are out, they all run off different switches (and the other lights in the switch row all work).

If the three lights are all on different switches then in most cases that means three transformers, since you also say tried halogen lamps then unlikely under current problem.

It seems you have not got power to the switches, it is normal for each ceiling rose to have a cable twin and earth go from ceiling rose to switch, even with 8 switches it's common to have 8 permanent line feeds, so if converted from ceiling rose to down light then the line will be independent from each other. So if the person converting from ceiling rose to down light has not used a maintenance free junction box to join the wires, it could be as simple as a screw coming loose.

Without a crystal ball we are just stabbing in the dark.

 

[PrenticeBoyofDerry]

It might be the transformer, but does each lamp have its own transformer,

In your case very probably

or does one transformer run numerous lamps

They can, but by evidence you have given unlikely to be your issue

(and coulf it run all three in row, hence why mine have gone).

Not if they are on different switch lines

But the transformer looks quite new and shinny (not the best measure for it being broken I know!).

No that method of fault finding does not really stack up

Also does anyone have any other ideas as to what could be the problem.

Faulty lamps, faulty lampholders, loose or damaged connections and damaged cables.

I assume they did work?

 

[Stewart Birrell]

Hi guys thanks for the reponses, it is difficult I know. Below is a picture of how thw lights are set up and working (o) / not (x). 1,2,3 represent three seperate light switches, so when i turn on 1 the 1st, 3rd and 4th lights turn on. I have removed the light fitting not working on switch 2, and this had the transformer (see pciture attached). I have not removed any other fitting to see if they have a transformer.

1 2 3
o o o
x x x
o o o
o o o

 

[PrenticeBoyofDerry]

They will have transformers if your using 12V lamps.
It is the most likely fault that tranies have failed, but don't rule out faulty lamps, lampholders, loose/damaged cable/connectors or a combination of them all.

 

[Stewart Birrell]

I have changed the cables and these are not burnt out, but I will check loose cabelling as they were working before. I will also try to find a working transformer and replace this with the faulty one. Thanks for the help so far.

 

[ericmark]

Two things, one it says "Electronic transformer" the electronic is important, second it says 20 - 60 VA, as far as you need to know VA is the same as watts, so what it says in layman's terms is the transformer will work with a bulb between 20 and 60 watt, in the main LED bulbs are under 20 watt so will not work. The word electronic tells us it may have an output which is not 50 Hz, many LED bulbs are actually marked 50/60 Hz so are in theory not suitable.

So likely the electronic transformer is the problem, if the bulb does not state 50/60 Hz then likely you can use a suitably rated electronic transformer as linked to but to be sure it needs to be like this one

to work with LED bulbs normally found for sale.

Some LED bulbs are DC but in the main these are used for caravans and are more expensive. Most are also 12 volt but again caravan ones are often 10 ~ 36 volt. A driver is normally DC in theory it should be current control, in practice many power supplies for LED lights are still called drivers when they are voltage regulated. You really need to read the spec.

I prefer low voltage lamps (230 Vac) as it is so hard to get everything to match with extra low voltage, and in the main with LED there is no need for extra low voltage.

 

[EFLImpudence]

That doesn't explain the strange configuration of working and non-working lamps.