How to check if spotlights are AC or DC?

[mameha]

I have several GU5.3 halogen spotlights in the bathroom.

I think they are relatively modern, maybe installed 5-10 years ago.

I want to replace them with LED, but it seems that you cant replace halogen with LED unless they are on DC circuit.

Is there any easy way to test for AC DC before buying the LED bulbs?

I have a multimeter. I can also get to the bulbs from the loft however it is a pain lifting the floorboards etc.

 

[securespark]

If there are any, you should be able to access the transformers from below, unless it is a central multi-lamp unit.

On them, it will state the output, usually around 11.5V AC

If they don't have transformers, they will be fed direct with 230V AC.

The lamps will say what voltage they are rated to.

 

[winston1]

GU5.3 halogen spotlights invariably run off AC either via a 12 volt transformer or more likely these days a PWM switch mode power supply.

Looking at the supply feeding the lamps should be able to tell which.

To replace with LEDs much better to use 240 volt types and dispense with the supplies altogether. You would also need to change the bases from GU5.3 to GU10.

GU5.3 LEDs will usually run on AC but you should use a dedicated LED supply. Ones designed for halogen lamps often won't work properly.

 

[stem]

The GU5.3 (aka MR16) refers to the 5.3mm distance between the pins. I believe 230v versions are around but I would expect them to be 12v but the power supply could be AC or DC. It is possible to test with a multimeter at the light to see which it is without lifting floor boards.

If they are 12v, you can get LED's to replace them Some LED's are suitable for both AC and DC there's an example here.

 

[mameha]

I'm tempted just to get these and see if they work, take them back if not:
http://www.screwfix.com/p/lap-mr16-led-lamps-gu5-3-345lm-4-5w-5-pack/8794p

At the bottom it says they dont need a transformer.

 

[winston1]

The GU5.3 (aka MR16) refers to the 5.3mm distance between the pins. I believe 230v versions are around but I would expect them to be 12v but the power supply could be AC or DC. It is possible to test with a multimeter at the light to see which it is without lifting floor boards.
[ /QUOTE]

The bit in brackets is misleading and confusing. MR 16 refers to the size of the reflector in eights of an inch and is nothing to do with the base. Many 240 volt GU 10 base lamps are MR 16.

A multimeter is not a reliable method of testing for AC or DC. If the supply is a PWM switch mode type (most likely) it will be operating at tens of KHz and most DIY multimeters won't respond.

Also such supplies are not suitable for LEDs AC or not.

 

[winston1]

I'm tempted just to get these and see if they work, take them back if not:
http://www.screwfix.com/p/lap-mr16-led-lamps-gu5-3-345lm-4-5w-5-pack/8794p

At the bottom it says they dont need a transformer.

Indeed it does. It also says on the base 12 V, 50 Hz. If your mains supply is 240 V you will clearly need a transformer and NOT a PWM switch mode supply.

 

[mameha]

Can i test whether the socket is 12v or 240v with a multimeter?

 

[winston1]

Can i test whether the socket is 12v or 240v with a multimeter?

Not if the 12 volts is at tens of KHz from a PWM switch mode supply.

 

[endecotp]

Is there any easy way to test for AC DC before buying the LED bulbs?

I have a multimeter..

Yes. What does the multimeter say on DC volts, and what does it say on AC volts?

 

[EFLImpudence]

Is there any easy way to test for AC DC before buying the LED bulbs?

Won't it be written on the present ones?

 

[ericmark]

I'm tempted just to get these and see if they work, take them back if not:
http://www.screwfix.com/p/lap-mr16-led-lamps-gu5-3-345lm-4-5w-5-pack/8794p

At the bottom it says they dont need a transformer.

I note on the picture of the lamp it states:-

4.6W 345lm 410mA 12V 50Hz 2700K 36° 2016-3-9

as well as

Dia x L: 50 x 46mm. 4000K. Transformer not required. Beam angle: 36°.

I do wonder how you would get 12V 50Hz without a transformer? Some sort of rotary converter or vibrator

to get the 50 Hz. I suppose "An Electronic Transformer" is not a transformer but unlikely to supply at 50 Hz. I would say Screwfix have screwed up on that advertisement. Also it us G5.3 not GU5.3 as clearly no a bayonet connection. And neither is it MR16 as there is not multifaceted reflector and the light area is not 16/8 of an inch across it has a package which means most of the 16/8 of an inch is non light emitting plastic.

This is of course the problem, the lighting industry in general don't seem to have a clue what they are selling, with have ballasts with no ballast in them just a load of electronics, electronic transformers which are pulse width modulated high frequency 12 volt power supplies, and the list goes on and on.

So as already said easy way is convert to GU10 and use 230 Vac direct as to get 50 Hz at 12 Volt you need a toroidal core transformer like these

which I have powering the four G5.3 lamps I have, however when I replaced the lamps with LED they did not last long, so even when it is the right power supply they still seem to fail.

 

[mameha]

OK so I went into the loft and took some photos from above.

 

[333rocky333]

That transfomer needs a minimum of 20 watt to run properly, so likely your leds will be unstable

Unable to read what it says regarding leds

 

[EFLImpudence]

http://gb.auroralighting.com/Lighti...A-Self-Monitoring-Electronic-Transformer.aspx