Basic Lighting Question - Halogen/normal to LED conversion

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axumazza

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Hi,

I'm a complete beginner with all this so apologies and bear with me.

I have a house that has loads of the old MR16 (dual "pins") bulbs as downlights. I have bought a load of replacement LEDs bulbs to match the fittings.

My understanding is that the original Halogen MR16 bulbs will have transformers attached (I can't really tell as everything is in the ceiling cavity and i'm worried about pulling on the wires too hard!).
I have replaced all the MR16 halogen with leds. Everything seems to work fine aside from a couple of sections of lights (see Q2 below).

Question 1 : Is this OK to just swap out halogen with LED bulbs like this ?
Question 2 : In an area of the house that used to be the garage and has been converted, a couple of the LED bulbs are flickering. If i place 2 normal Halogens back into fixings, the rest of the LEDs work fine - is this OK to do ?

Question 3 (unrelated to the above) : I understand that certain bulbs, GU10 etc, have in-built drivers to reduce the incoming power ? My mum has an old house, i'm sure there will be no transformers etc, if she gets fittings which take the types of bulbs that have in-built drivers, does she need to do anything else ?

Many thanks in advance!
 

Richard-the-ninth

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In reverse order.
Any GU10 LED lamp will be ok, it is as you suggest a straight swap, but do change them in the day with the lights off.


MR16 lamps are 12v and the mains being 230v ac you need something to transform the 230vac to 12vac so you will find that your lights have "transformers"

Examples: (I made the money figures up)
20watt lamp needs 20+ watt transformer (Say £7 each)
6 x 20 w lamps require 6 transformers = £42

Enter the big 150 w transformer it costs £21

You can figure the rest yourself.

So in an ideal world each lamp has its own transformer, but not every lamp has. It sounds like your garage has one big transformer.

Now for the spanner in the works.
LED lamps require DC current to work properly (Halogen lamps work with AC or DC) "Transformers" are not really transformers, they are electronic voltage reducers, the output from them is neither true DC or AC. (You need not worry about the why, it is just the way they work) So to run an LED MR16 is possible, it's just that it will not last as long as it could if it was run on pure DC which you can get if you have an "LED Driver" Again preference is one driver for each lamp.

As an aside, Transformers have a minimum and maximum rating. e.g. 20w Min 150w max so if you were to connect 6 x 3w LED lamps the transformer will not work as it only sees 18w, but if you add a 20w halogen it now sees 38w so it will work, but the LED lamps will not last as long, as previously mentioned.

Some folk take the best route which is to have all the light fittings changed to ones that accept GU10 lamps, no drivers or transformers required. (Some re wiring may be needed.)
 

axumazza

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Well, what can i say, thanks so much for the in-depth response.

So, to summarise, GU10 (and any bulbs that have in-built transformers) are fine as straight swaps (taking all the normal precautions).

The setup i currently have is fine, there's no problem with it as such, but the LEDs may well not last as long.....which I guess partially defeats the object (along with their reduced power consumption). So, ideally, i would transform all fittings to GU10, second best would be to get LED Drivers.

The problem i have is that i have roughly 50 of these MR16 downlights in the house!!
 

axumazza

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I think I’ll just stick with what I have to be honest. I’ll reconsider if all the new LED bulbs start blowing!
 

Mike P

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If you are changing 12v halogen to 12v LED the transformers need to be changed to LED drivers as they are what they call “constant current”. If changing from 12v to 230v Led, you need to remove the transformers and connect direct to the lighting circuit. As pointed out earlier any 230v fittings need to be earthed, whereas 12v (extra low voltage require no earth.
 

BorisJ

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Hi,

I'm a complete beginner with all this so apologies and bear with me.

I have a house that has loads of the old MR16 (dual "pins") bulbs as downlights. I have bought a load of replacement LEDs bulbs to match the fittings.

My understanding is that the original Halogen MR16 bulbs will have transformers attached (I can't really tell as everything is in the ceiling cavity and i'm worried about pulling on the wires too hard!).
I have replaced all the MR16 halogen with leds. Everything seems to work fine aside from a couple of sections of lights (see Q2 below).

Question 1 : Is this OK to just swap out halogen with LED bulbs like this ?
Question 2 : In an area of the house that used to be the garage and has been converted, a couple of the LED bulbs are flickering. If i place 2 normal Halogens back into fixings, the rest of the LEDs work fine - is this OK to do ?

Question 3 (unrelated to the above) : I understand that certain bulbs, GU10 etc, have in-built drivers to reduce the incoming power ? My mum has an old house, i'm sure there will be no transformers etc, if she gets fittings which take the types of bulbs that have in-built drivers, does she need to do anything else ?

Many thanks in advance!
1. Probably not. LED spotlights are designed (often labelled) DC or 50/60Hz AC. Halogen power supplies often operate at 10s of kHz. You LEDs won't appreciate being at 200 times their designed frequency.
2. That is one of the symptoms of an incorrect supply.
3. Should be OK.
 

BorisJ

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In reverse order.
Any GU10 LED lamp will be ok, it is as you suggest a straight swap, but do change them in the day with the lights off.


MR16 lamps are 12v and the mains being 230v ac you need something to transform the 230vac to 12vac so you will find that your lights have "transformers"

Examples: (I made the money figures up)
20watt lamp needs 20+ watt transformer (Say £7 each)
6 x 20 w lamps require 6 transformers = £42

Enter the big 150 w transformer it costs £21

You can figure the rest yourself.

So in an ideal world each lamp has its own transformer, but not every lamp has. It sounds like your garage has one big transformer.

Now for the spanner in the works.
LED lamps require DC current to work properly (Halogen lamps work with AC or DC) "Transformers" are not really transformers, they are electronic voltage reducers, the output from them is neither true DC or AC. (You need not worry about the why, it is just the way they work) So to run an LED MR16 is possible, it's just that it will not last as long as it could if it was run on pure DC which you can get if you have an "LED Driver" Again preference is one driver for each lamp.

As an aside, Transformers have a minimum and maximum rating. e.g. 20w Min 150w max so if you were to connect 6 x 3w LED lamps the transformer will not work as it only sees 18w, but if you add a 20w halogen it now sees 38w so it will work, but the LED lamps will not last as long, as previously mentioned.

Some folk take the best route which is to have all the light fittings changed to ones that accept GU10 lamps, no drivers or transformers required. (Some re wiring may be needed.)
MR16 lamps can be 12v, they can also be 24v, 120v, or 240v. MR16 means multifaceted reflector 16 eights of an inch (2") in diameter. GU10 240v spotlights are usually MR16.
 

axumazza

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1. Probably not. LED spotlights are designed (often labelled) DC or 50/60Hz AC. Halogen power supplies often operate at 10s of kHz. You LEDs won't appreciate being at 200 times their designed frequency.
2. That is one of the symptoms of an incorrect supply.
3. Should be OK.
Hi,

Thanks for the reply.

So, i should mention, the old MR16 bulbs are 12V, the new LED versions are also 12V.

It sounds like what you've said in 1) may mean that, at some point, my lights will go POP! - as at the moment, they are all running without issue (apart from the one area of the house, but now i have put in 2 Halogen bulbs, they are also running fine).
 

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