MR16 12V power usage?

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Zuluzebra

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I recently bought and moved into a new house. Once settled I was on a mission to change all lighting to led's, starting with the 4 500w spotlights they had outside!! Which I changed to 4 20 watt led's.

Then I wanted to change all the downlights throughout the house - 62 of them to be exact. I saw a GU10 warm white special at makro, 2 for R20 - so bought 40 to get things started. As I got home (very excited I might add) and took out the first downlight I was shocked to see that they were MR16 lights (the 2 pin ones).

Luckily I managed to sell them quickly and was on a mission to get well priced MR16 downlights as they are generally more expensive - as new houses tend to stick to GU10 as don't need a transformer.

So my question is. How much power does the transformer use when the light is on? I managed to buy 62 5w MR16 LEDs and replaced the whole house only to have different comments from people to say it won't really make a difference - reason is the 62 50w halogens that I replaced was each managed by its own 12 volt transformer so not a using full 50 watt.

My research online can't give me solid answer in terms of power usage, only comparisons between MR16 and GU10.

Sorry for long story, but it gives some background. Below LEDs I bought to replace all the 50watt halogens.

ea52e407e37a54c2170ac7a9a72ddb9a.jpg


50d0300c50b1eb3f57452985a6b5ebb8.jpg
 
The transformer converts the voltage from 220/240 to 12v, that's all.
 
Chris_SA said:
And how many watts does the transformer use?
Click to expand...

Depends on efficiency under the given load. But you're now running them at lower load, so efficiency will be better than before, and was probably 90%+ to start with. So I'd expect it to be about half a watt now compared to say 5W under halogen.

You won't be consuming more power now than before. But there's still the question of if/when you break even on the energy savings given the outlay. Back of the envelope suggests about 17 months. If your warranty is 3 years you should be good.
 
Being a budding DIY electrician myself I am very intrigued by these transformers that you guys always talk about, why was it necessary to covert to 12V in the first place?
 
Tomtomtom said:
Depends on efficiency under the given load. But you're now running them at lower load, so efficiency will be better than before, and was probably 90%+ to start with. So I'd expect it to be about half a watt now compared to say 5W under halogen.

You won't be consuming more power now than before. But there's still the question of if/when you break even on the energy savings given the outlay. Back of the envelope suggests about 17 months. If your warranty is 3 years you should be good.
Click to expand...

So if I had a 50w Halogen under the transformer, it could have pulled 55w (light and transfomer) and now pulling 5w with 0.5 with transformer?

I paid R17 a light so wil break even sooner I think :)
 
What is the current setup? Do you have a few large transformers powering the globes or do you have an inline transformer per globe?

If it's inline, I'd just pull it out and replace it with GU10 connecter (they're cheap and you can get them from most hardware stores). It's very easy to do. If the transformers are inline, there is a good chance they won't work with 5w globes - the electronic transformers require a minimum current to work (usually only work from 10/20W up). Iron core transformers work from low power, but they are incredibly inefficient.

Then it can get very tricky if you want to use a dimmer with a MR16 LED setup.
 
me_ said:
What is the current setup? Do you have a few large transformers powering the globes or do you have an inline transformer per globe?

If it's inline, I'd just pull it out and replace it with GU10 connecter (they're cheap and you can get them from most hardware stores). It's very easy to do. If the transformers are inline, there is a good chance they won't work with 5w globes - the electronic transformers require a minimum current to work (usually only work from 10/20W up). Iron core transformers work from low power, but they are incredibly inefficient.

Then it can get very tricky if you want to use a dimmer with a MR16 LED setup.
Click to expand...

I looked at that option but not feasible to replace 62 MR16 fittings and get downlights replaced.

Yes each light has its own transformer.
 
Chris_SA said:
I looked at that option but not feasible to replace 62 MR16 fittings and get downlights replaced.

Yes each light has its own transformer.
Click to expand...

62 - wow - approximately 55W per globe (globe plus transformer loss), that's around 3.4KW. Your electricity bill must be crazy. Next time there's loadshedding, can you just do us a favour and switch off your lights :)

We had quite a lot of MR16s (not quite 62), but I replaced them in stages starting with the lights that are on the most. I still have one room to go, but the lights are on so infrequently in that room that it's not going to be a big saving.

If you get a MR16 LED and start pugging it in randomly, you'll probably find it won't work with the majority of transformers. Also, the transformers fail relatively frequently and the cost of replacing those continually with the more expensive globes really isn't worthwhile.
 
me_ said:
62 - wow - approximately 55W per globe (globe plus transformer loss), that's around 3.4KW. Your electricity bill must be crazy. Next time there's loadshedding, can you just do us a favour and switch off your lights :)

We had quite a lot of MR16s (not quite 62), but I replaced them in stages starting with the lights that are on the most. I still have one room to go, but the lights are on so infrequently in that room that it's not going to be a big saving.

If you get a MR16 LED and start pugging it in randomly, you'll probably find it won't work with the majority of transformers. Also, the transformers fail relatively frequently and the cost of replacing those continually with the more expensive globes really isn't worthwhile.
Click to expand...

Already replaced all 62 with the 5w led pic in my first pic. All working perfectly.

Luckily lights not on all the time...
 
Chris_SA said:
Already replaced all 62 with the 5w led pic in my first pic. All working perfectly.

Luckily lights not on all the time...
Click to expand...

You're very lucky - About 80% of my transformers were these:
https://lux365.com/osram-et-parrot-70w-transformer-for-low-voltage-halogen-lamps.html
If you look closely in the picture, you'll see minimum wattage of 20W so if I were to use LEDs, I would need a minimum of 5 per transformer which would have been a complete rewire anyway. Ripping them out and putting in GU10s was far easier.
 
Chris_SA said:
I looked at that option but not feasible to replace 62 MR16 fittings and get downlights replaced.

Yes each light has its own transformer.
Click to expand...
Even though you stuck with MR16, if your bulbs blow in future , just pull out the transformer and then replace with GU10 lead to switch to native 220v. Hopefully, there is enough cable slack to do this.

In my case, similar amount of lights and i changed to GU10 without needing to change the fittings . I had to go into roof for a few of them where there was no slack so then replaced the cables.

3 months later, was at China mall and they had stainless steel fittings .. and at due to volume, at special price, worked out to R4 each with no tilt functionality. :)

Went home and changed everything from the very old heavy white fittings to nice steel ones in about 90 mins

Also without transformers, no hum when lights are on .1533969859654.jpg
 
thechamp said:
Being a budding DIY electrician myself I am very intrigued by these transformers that you guys always talk about, why was it necessary to covert to 12V in the first place?
Click to expand...

12v was often used in bathrooms for safety purposes, ie 12 v is safer than 220v when lots of steam around.

No good reason for using 12v elsewhere in the house.
 
Did this in my grans house recently. Replaced all the 12V 56W halogens with 220v 5W LEDs. Simply ripped out all the transformers
 
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