Led Replacement Lights

[arabbadot]

I have a series of light fittings taking mr16 halogen lamps-- the 2 pin push into two small holes type-- and was going to replace with LED two pin type.
I am told this might blow the whole fitting. Any truth in that?

[douglas9401]

If the fitting runs off straight mains then no problem. If it uses a transformer for low voltage halogens then it probably won't work.

[TheChair]

MR16s are 12 volt lamps. You'd think that it would be easier to match the LED lamps to a 12 volt supply than it is to 240 volt supply, but unfortunately it's not.
The 12 volts from the transformer needs to be stepped down even further, which means that the LEDs (like ones designed for 240 operation) still need driver circuitry, and thus need to dissipate heat - quite difficult to achieve in such a small package.
The other problem is that, because they draw much less current than halogen bulbs, the existing transformer, which is designed to work into a much higher load, may also experience problems.

[TheChair]

Furthermore, LEDs, of course are DC devices, so the supply also needs rectification and smoothing. Electrolytic capacitors are normally used for smoothing purposes in power supplies, but these are fairly large, and once again come up against the small package size of the MR16. Ceramic capacitors are smaller but can buzz, and may also break down.

[TheChair]

You could replace the existing transformer with one designed specifically for LEDs, such as this:
http://tinyurl.com/p4goluh
But that would mean that you could no longer user halogen lamps.
If you have a dimmer, you might need to replace that as well.

[bhg481]

I've bought LED bulbs from these people (not mr16s). It could be worth sending them an email.
https://www.brightlightz.co.uk/catalogsearch/result/?q=mr16&;cat=The+Entire+Shop

[The Builder]

Good posts from TheChair and the others. First off... it is possible to successfully replace all conventional lamps with LEDs. I do it all the time.

Older type transformers (12 volt lamps) can, sometimes, work well with LEDS. If not, they flicker badly. They should have the newer type of electronic transformers to work properly.

LED lamps are no problem at all at 240 volt. With the right transformer, they are also perfectly fine if they are the 12volt variety.

[arabbadot]

Thank you all for the advice. Given that the LED s are so cheap to run there does not seem to be any point in running low voltage in the recessed ceiling lights.
The other problem though is when you have a chandelier type of fitting with several lamps all fired from a central transformer built in to the fitting. Would you need to replace the whole fitting?

[The Builder]

A bit of trial & error needed there, Arabb. Try just replacing the lamps first. If everything's Ok, and no flickering, then fine. Since the load from several lamps will be higher than from one only, the transformer may well operate fine.

If not, then simply install an electronic driver (transformer) in the ceiling void, and bypass the existing one.

[arabbadot]

ahh yes of course. Bypass with a suitably sized LED transformer would be far cheaper. Thank you