question MR11 to MR16

23 May 2015
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West Midlands
United Kingdom

For the most of you this may sound silly, but I m really scratching my head about this:

I have 10 MR11 (halogen 20w each) but ordered -online- by mistake MR16 LEDs (4.5w each)
another problem is that I can't reach the transformer - so no idea what is the wattage of it,
but I assume its minimum 200w as all of the halogens are 20W and I am using them for years...(installed by
some previous owner of the house).

What a friend told me and I later read it on the net is I "can't" use those 4.5w as in fact they consume more
power ..? Its something I can't understand.. isn't 10x4.5 = 45watt the whole? Can someone pls help me there?

thanks in advance.
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You are correct, 45 watt total so if the power supply can give that low of an output then should be no problem. Depends how old, if a real transformer no problem if it's an electronic transformer may be it will not work with such a low output.
aha that's it then, nothing like they are consume in fact "more" power..
thank you very much for that, now I got it.

I think I can solve the low power requirements if I leave 1 or 2 of the old halogens, even say I will replace 8 of them I will have 20+20+(8x4.5)=76w way less than the 200w that is now and in the future I will try to
find and replace the transformer
If it is one 200w electronic unit, then its likely to have a minimum load of 40w maybe 60w.
If there cabinet lights its possibly 2 or more units maybe 105watt maximum units.
the smaller units tend to have a 20 watt minimum.

Many dont tend to use one big 200w unit as the lampholder wires are generally thin and in the event of a short circuit, the cable insulation can sometimes melt before the units internal short circuit protection operates.
Last edited:
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Thanks mate for this info, downlights in kitchen.

Once, while tying to change one of them I accidentally disconnected a cable and the rest of the 5 lights stopped
working, so I assume all of them are chain-connected to one transformer -or maybe I am wrong and is just 4 of them on one TX and the rest 6 on the other... . but anyway I will install today the LEDs - bases fit , its the universal MR11/MR16 type, just a testing before I will go to buy the bigger brackets.
please let us know how you get on, Leds and transformer compatibility can be a pain unfortunately
all of the LEDs are working fine! it seems the 45w are inside the minimum requirements of the transformer(s)

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