by ericmark »
Thu Aug 30, 2018 5:15 am
I have 12 volt G5.3 MR16 fittings in my bathroom powered from a transformer, it was a simple case of replacing the quartz lamp with a 12 volt 50 Hz LED lamp.
However many extra low voltage MR16 G5.3 lamps are not supplied from transformers, but use electronic transformers, which are really switched mode power supplies, these typically at 35 - 105 VA which means they will work between those two figures, and also the output is often in the kHz range, as a result often a limit to about of cable you can use and often the LED does not use enough power to be within the minimum or 35 VA.
There is also a possibility fitting diodes to these can turn them into radio transmitters, and many of the LED bulbs are marked 50 Hz which means to be sure they will work you need a transformer not an electronic transformer.
MR16 = multi faceted reflector 16/8th of an inch across. i.e. 2 inches. So both G5.3 pins used with 12 volt and GU10 bayonet used with 230 volt are both MR16 lamps. However often 12 volt are called MR16 and 230 volt GU10. Bit like writing FM and MW on a radio one refers to modulation type, the other frequency, should say VHF and MW or FM and AM but often mixed, same with bulbs.
So 12 volt LED MR16 replacement are mainly 50 Hz, but you can get DC versions often 10 - 30 volt mainly designed for caravans and boats, the latter must have a DC supply, although those marked 50 Hz should have an AC supply they will often work OK with DC.
LED's themselves are current dependent, and they always have a driver which limits current, however in the main this is built into the lamp, so we only need to control voltage. However for some unknown reason the lighting industry seem to call 12 volt DC power supplies drivers, so you have real drivers often rated something like 320 mA where all lamps are connected in series, and simple 12 volt power supplies also with the name driver written on them. Many people I know do use 12 volt DC power supplies to power 12 volt MR16 replacements, but since often marked 50 Hz really should use a transformer.
There are two reasons for using 12 volt quartz lamps rather than 230 volt, one is because where they are used requires extra low voltage as in bathrooms, the other was the filament was thicker so lasted longer, moving to LED they latter reason has gone, so in a kitchen I would consider moving over to 230 volt versions the GU10 lamp.
However 2 inches is not very big, and with cooling fins they are not even 2 inches, so to light a room the spot light needs to shine onto a white surface which will reflect and spread the light, small wattage LED GU10 works well, 2 to 4 watt as a reading lamp next to bed is great, but 7 watt will only light the room if reflected off white wall or ceiling.
LED lights can be made quite thin, so there is no need for them to be let into the ceiling, so a 2 inch light can be replaced with a 4 inch light without need to either fill in hole or make hole bigger, and 4 inches will light the area with 7 or 10 watt without needing to reflect the light. There are also those which do let into ceiling.
I would consider using larger diameter lights with LED. My kitchen has 28W of lighting, my sons half the size has 42W of lighting but when I went to set his boiler I needed a torch, lumen counting only works if you get a good spread of light.
