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Discussion Starter · #1 ·
I have a new house with many downlights at 50W each. With a view to save some power I purchased a dozen 4W LEDs to replace the halogen bulbs in the most heavily used fittings.

Initially I replaced four of them and switched on. All was bright for about an hour then two of them flickered and died. A little exchange experiment shows that the Luxalite GD32LH transformers on each fitting have died.

I am now reluctant to go and exchange the other lights as I don't want to replace a large number of transformers - and what would I replace them with?

Any suggestions as to what approach to take?
 

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Discussion Starter · #3 ·
Yes they are electronic transformers.
How do I find how much load they require? Can I achieve that by rewiring the fittings in parallel?
Is there a better approach?
What happens when a fitting is powered up without any bulb at all?
Are the dead fittings recoverable?

Thanks for any suggestions. Peter
 

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Yes they are electronic transformers.
How do I find how much load they require? Can I achieve that by rewiring the fittings in parallel?
Is there a better approach?
What happens when a fitting is powered up without any bulb at all?
Are the dead fittings recoverable?

Thanks for any suggestions. Peter
There should be a wattage rating on the transformer. I believe you will be ok with a 50% load.

You could parallel but you may end up with a lot of lights hooked together.

I don't have any better approach ideas.

The transformer may not start up at all with no load so it might be ok. You will just have to check them out.
 

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It may not just be an issue of the amount of load, but also the type of load. Most electronic transformers operate at very high frequencies and are not intended to power anything but an incandescent lamp. Most LED lamps have electronic power supplies in them that expect to receive 60Hz power. Using a high frequency transformer with an LED lamp that's not specifically designed for it could result in either the lamp or the transformer failing.
 
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The word fitting sound like you are from UK or Aussie area is that correct?

Now with the electroic transformers I know one poster did nailed on that one and also if run at wrong supply voltage that will do the same thing.

And this transformer is vented or got overheated if overheated you will have to check why it causing to overheat due poor ventation ( most common cuprit )

Merci,
Marc
 

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The word fitting sound like you are from UK or Aussie area is that correct?

Now with the electroic transformers I know one poster did nailed on that one and also if run at wrong supply voltage that will do the same thing.

And this transformer is vented or got overheated if overheated you will have to check why it causing to overheat due poor ventation ( most common cuprit )

Merci,
Marc
He is going from a 50 watt load to a 4 watt load. Same supply voltage and was working ok stock with the 50 watt load.
 

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He is going from a 50 watt load to a 4 watt load. Same supply voltage and was working ok stock with the 50 watt load.
I am aware with that but let me address to the OP this part did the OP do have dimmer switch or not ? If the OP did have dimmer switch there are some of them need minum load to keep it running so once you drop below X numbers of wattage to keep it running it will kinda like drop out.

And going from Incandsent to LED that will useally wreck hovac if not watching the power supply espcally with dimmers due some of the LED drivers will not take dimmer at all.

Merci,
Marc
 

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Now I can see where this going and you did have 12 volts 50 watt halogen bulbs and go with LED and with electronic transfomer it can wreack hovac but magatic not too bad.

Do you know what brand name of the LED bulb that you are trying ?

Merci,
Marc
 

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The LEDs are unbranded (Chinese).
The boxes are marked:
MR16 4*1W​
12VCE RoHS​

Thanks for your interest, Peter

Probly they are cheap stuff that why it don't last long if you get little more expensive stuff like well knowen namebrand you may have less issue with it.

So try that route to get better qualnty LED device.

Oh the other thing check with the label to make sure they will work with recessed fitting ( Cans for stateside guys )

Merci.
Marc
 

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Where is it stated that the voltage of the lamp has been matched to the voltage of the luminaire?
I wanted to ask mpoulton about his comment last night but I was busy on another thread and he went offline. Are LED's even supposed to work with low voltage AC and electronic transformers?

Note to French Electrician. According to the OP his transformers were biting the dust, the LED's were surviving.
 

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To the OP.....I just did a search on your transformer and it took me to a 6 watt 12 volt DC LED PDF. In the last page of the PDF it lists your transformer being able to power 1-6 of these particular LED lamps.

So....I don't know why you are blowing transformers other than the fact that your LED's are 4 watt and may be different in some other way.

http://www.1000bulbs.com/pdf/lsg-definity-mr16-specs.pdf

If you look at some of the other electronic transformers you will notice that they list "f for flickers" for different quantity of lamps which it what I was saying in my first post about the load. Maybe 4 watts just isn't enough of a load to keep your transformer happy?

If it's easy to do, try wiring 2 lamps with one transformer like you originally mentioned or try a 6 watt LED.
 

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Discussion Starter · #17 ·
to Zappa

I agree that the LED manufacturers brochure suggests that the transformer should be happy with only one LED on the circuit - however that is the assessment of the LED supplier not the transformer supplier. Simple fact is that the transformers are falling over dead with only one LED on circuit.

Other transformers are said by some to be suitable, but when I look up the specs there is a minimum load requirement of about 20W in all I have seen.

While I could wire several LEDs in parallel to get a total load of 20W (5 luminaires) I wonder if the characteristics of that load might not still be unsuited to the transformer.

BTW the transformer output is 12V and the LEDs are 12V also - I had not thought it necessary to confirm that I am not that stupid.

Thanks for your interest, Peter
 

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To the OP.....I just did a search on your transformer and it took me to a 6 watt 12 volt DC LED PDF. In the last page of the PDF it lists your transformer being able to power 1-6 of these particular LED lamps.

So....I don't know why you are blowing transformers other than the fact that your LED's are 4 watt and may be different in some other way.

http://www.1000bulbs.com/pdf/lsg-definity-mr16-specs.pdf

If you look at some of the other electronic transformers you will notice that they list "f for flickers" for different quantity of lamps which it what I was saying in my first post about the load. Maybe 4 watts just isn't enough of a load to keep your transformer happy?

If it's easy to do, try wiring 2 lamps with one transformer like you originally mentioned or try a 6 watt LED.
The reason why the electronic trannys are dieing is two fold _
1 - All electronic trannys require a minimum load to operate correcttly,
usually it is around about 50% of its rated capacity, say 25 to 30 watts.
A 4 watt led is too light a load !

2 - The nature of the load, some led lamps incorperate
some electronic circuitry, this can represent an inductive or
capacitive load for the power supply, now if the power supply
is it self an electronic type, it may not like the back emf
that reactive loads can introduce.

I would use a 12v plug pack at each led fitting.
that way no major changes to wiring is necded.
Plug packs are cheap and readily available.
I have done it, and it works just fine !
 

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I would be willing to bet that they are really cheap 'electronic transformers'. One of the cheapest ways to make one is to use a capacitor in series with the line voltage and a bleed resistor. The current available is a function of the uf of the cap....the voltage ends up being what ever the ESR of the cap is....the end result being that the output is a pulsed AC 'around' 12 v.....without a load, the voltage goes up quite a bit....which would toast low voltage/wattage devices.

In the OP's case, since the 'transformer' died, I'm guessing it's a bit more than just a cap....maybe has a zenier diode for protection....I doubt it is a true switching transformer....

In cases like this....a 'real' transformer is the way to go.....especially for such a light load.... 0.3333Amps @12Vdc per light.
 
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