Replacing a group of six dimmed halogens with LEDs

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rossmcm

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#290801 6-Dec-2021 11:02

I have a group of 12v MR16 downlights on a combined wall switch/dimmer. The halogens and transformers have shown poor reliability and I want to replace them with a set of 6 dimmable LEDs.

I'm assuming that the circuit topology will need to be similar - i.e. a 230v LED-friendly dimmer feeding six transformer/LED lamp pairs.

It might make sense to do away with the six individual transformers and replace them with 230VA dimmable GU10 LED's?

Can anyone offer suggestions/caveats/past experience on this?

Thanks

wellygary

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#2824947 6-Dec-2021 11:23

TBH, If its a lounge room you spend alot of time in (esp in winter) I would seriously look at replacing each of them with a sealed LED unit of a similar diameter..

The reason is that new units will result in a sealed ceiling, MR16 cans badly leak heat into the roof space,

(now when you have a 70W halogen providing most of the heat it's not really an issue, but with a <10W LED, its mostly room heat that will be leaking out into the roof. )

robjg63

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#2824986 6-Dec-2021 12:14

I would replace the whole light fitting - if that is what you were asking.

Otherwise, you can get LED replacements for MR16 bulbs that should just plug and play.

https://www.mitre10.co.nz/shop/ge-lighting-led-dimmable-mr16-reflector-7-watt-550lm-60deg-warm-white/p/380509

You would need to source LEDs that can be dimmed (the $20 ones above are dimmable).

Or these:

https://www.bunnings.co.nz/ledvance-6w-warm-white-gu5-3-dimmable-mr16-led-superstar-lamp_p4371480

($14 each)

You would also need to replace your dimmer with one that is built for LED bulbs - the old one will almost certainly not work.

In my experience LED's don't tend to dim as well as incandescent.

It can be quite a pain getting replacement lights that fit into the same cutout.

Nothing is impossible for the man who doesn't have to do it himself - A. H. Weiler

KiwiME

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#2825004 6-Dec-2021 12:45

I had the same layout 2 years back and initially tried just changing the MR16 lamps to 4W non-dimmable LEDs and replaced the dimmer with three switches, one for each pair. When one LED burned after a week out I checked one solid-state halogen driver on a 'scope and saw that it was providing around 30V to the poor 12V LED because the minimum load requirement was not being met. I could have rewired all 6 off one driver to meet that minimum, or change the drivers to more modern ones ($$) but I didn't.

Now, you'd have more options these days but I simply did what was suggested above - changed all to 6W 230VAC flush non-dimmable LED lamps that fit in the same 75mm hole. With 3 switches the lighting choices are sufficient and the wiring is more or less as it was.

I think the 230VAC GU10 type LED lamps are going to disappear very soon - I keep hearing that they're not reliable. The flush LEDs on the other hand are just awesome and can be easily replaced in 20 years from the room when they fail.

rossmcm

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#2825117 6-Dec-2021 15:57

Thanks for the comments. I'm interested in the comments re 230 V GU10s failing. Do you have a link?

KiwiME

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#2830323 11-Dec-2021 10:41

Sorry, I don't, it's just based on comments from staff at LightingDirect.

sparkz25

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#2830339 11-Dec-2021 11:24

For the cost of just the LED lamp and a new driver to run that lamp, you will be far better off replacing the entire fitting with a sealed unit as mentioned!

Most of the Sealed LED fittings nowadays are designed to be covered in insulation Hence the IC Abutted and covered rating, it is the driver that can not be under the insulation at all.

I have been through my entire house and replaced every downlight with these and they work great!, 13W 100mm cut out and tri colour LED module which will do 3000k, 4000k and 5700k, it made a huge difference from the old open can downlight, I have gone for a whiter colour as it looks better to me as opposed to a yellowish colour like the old incandescent lamps.

Going from 30+ 80-100w incandescent lamps to 13w LED has given us much more light in the living areas at night where it looks dark yellow and gloomy with the old incandescent lamps to a nice white light with much more intensity.

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neb

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#2830426 11-Dec-2021 16:16

wellygary:
TBH, If its a lounge room you spend alot of time in (esp in winter) I would seriously look at replacing each of them with a sealed LED unit of a similar diameter..

The reason is that new units will result in a sealed ceiling, MR16 cans badly leak heat into the roof space,

All that and one extra: MR16's as LEDs don't work, the form factor makes proper cooling almost impossible and both the form factor restrictions and who makes them means that they'll use totally subpar components and circuitry which, even without the inadequate cooling, leads to rapid failure. Toss the whole MR16 setup and put in ICF-rated LED downlights.

neb

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#2830440 11-Dec-2021 16:18

sparkz25:
I have been through my entire house and replaced every downlight with these

Yup, got exactly that at my house as well.

mattwnz

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#2830531 12-Dec-2021 02:19

KiwiME:

Sorry, I don't, it's just based on comments from staff at LightingDirect.

GU10s are very widely used. Many exterior wall lights for example use GU10 bulbs. We have had some LED ones for about 5 years, philips brand, and they have been fine. Many of these shops only sell their own brands.

I did the MR16 replacement about 5 years ago. Got some Philips MR16 for $5 each from Mitre 10 as they were selling them off . Think only one LED bulb has failed. Used to have lots of halogen ones fail, or the fitting used to have poor connections partly caused by the heat the halogen bulbs generated.
It worked out a lot cheaper for me, but the main reason I did it was because the light fittings were brushed chrome and small, and many of the LED all in one lights at the time were white, which can yellow over time. I also didn't want to have to drill new larger holes in the gib for the LED fittings, and the only fittings that I liked that may have been the right size were very expensive. So it was also a lot quicker to just switch over the bulbs. Had to replace a few of the drivers/transformers too when replacing the bulbs. But since I did it, there are far more LED choices, and probably ones with better hole sizes, and they have come down a lot in price, so would probably replace the whole fitting if I was to do it again