GU5.3 12v or 240v - how to identfy

[utterlydiy]

Been looking online for MR16 GU5.3 LED lamps to replace my 12v-50w halogen lamps.

When searching 'Screwfix' they have a large number of LED lamps, but they don't mention whether they are 12v or 240v in their specs. except in the occasional description of being 12v.

How would I identify which is which.

 

[JohnW2]

When searching 'Screwfix' they have a large number of LED lamps, but they don't mention whether they are 12v or 240v in their specs. except in the occasional description of being 12v. ... How would I identify which is which.

I may be wrong, but I think that most GU5.3s are 12V, so that's probably what most/all of them are. However, to make nothing more than a statement of the obvious, if their listing/catalogue doesn't indicate the voltage of items they are selling, probably the only way to find out would be to ask them!

Kind Regards, John

 

[winston1]

I don't think GU5.3s are ever 240 volt. They are normally 12 volt or occasionally 24 volt.

 

[ericmark]

You can get G5.3 in 120 volt and 230 volt, but only from internet, from screwfix they will be 12 volt, and GU10 will be 230 volt.

The LED G5.3 are often marked 50Hz so in theory are AC only, however in practice they are AC/DC I will guess the 50 Hz is to stop you using a switched mode power supply often called "an electronic transformer" although they are much more than a transformer, because they often have a minimum output, you are unlikely to have problems if the electronic transformer is rated 0 ~ 100 VA even if it is in the GHz ranger rather than 50 Hz.

It seems the lighting industry are very poor for names and description, they tend to retain old names even when they no longer apply, you will find LED GU10 lamps called MR16 they may be compatible with MR16 but they often have a lens less than 16 x 1/8th across and no multifaceted reflector so technically are not MR16. Same with electronic ballast and driver, but in UK shops not really a problem, only when buying from internet do you need to look carefully at what you are buying.

 

[JohnW2]

I don't think GU5.3s are ever 240 volt. They are normally 12 volt or occasionally 24 volt.

I also thought that, but Googling indicates that there are actually quite a lot of 220V-240V ones out there. However, as I said to the OP, I suspect that most/all of those being sold by mainstream UK suppliers are probably 12V.

Kind Regards, John

 

[utterlydiy]

It seems the lighting industry are very poor for names and description, they tend to retain old names even when they no longer apply, you will find LED GU10 lamps called MR16 they may be compatible with MR16 but they often have a lens less than 16 x 1/8th across and no multifaceted reflector so technically are not MR16. .

Sorry, how can GU10 lamps be called MR16 where the power pins are totally different.

 

[ericmark]

Sorry, how can GU10 lamps be called MR16 where the power pins are totally different.

GU10 and G5.3 refer to connection, MR16 refers to the size and type of lens, MR = multi-faceted and the 16 goes back to days of cathode ray tubes and refers to a used area with a diameter of 16 x 1/8" or 2 inches across, so you can get MR16 bulbs with E27, E14, GU10 and G5.3 bases.

 

[JohnW2]

Sorry, how can GU10 lamps be called MR16 where the power pins are totally different.

MR16 is nothing to do with pins. It refers to a Multi-Faceted reflector with a diameter 16 of eights of an inch (i.e. 2 inches). Although often referred to (often incorrectly) as "MR16", many GU5.3 LEDs will not actually be MR16 (per above definition).

Kind Regards, John

 

[winston1]

Sorry, how can GU10 lamps be called MR16 where the power pins are totally different.

GU10 is a type of base.

MR16 is the size of the multifacited reflector 16/8 of an inch, nothing to do with the base. Many GU10 lamps are in fact MR16.

Many distributers describe GU5.3 lamps as MR16. They may be but often are smaller.

 

[utterlydiy]

thanks, fully explained

 

[EFLImpudence]

Some of the choices on the Screwfix website:

Even the graphic is not accurate.
Never assume those in charge know what they are doing.

How long before GU5.3 actually becomes MR16 because of democratic inaccuracy.

 

[JohnW2]

How long before GU5.3 actually becomes MR16 because of democratic inaccuracy.

GU10 becoming MR16 would probably be more likely However, given that GUxx and MRxx have specific, well-defined and totally different meanings, I don't think that 'democracy' will ever alter that - i.e. the attributions which are currently incorrect will probably always be incorrect!

Kind Regards, John

 

[ericmark]

I think it should be G5.3 not GU however many adds do call them GU. Only the bayonet pins should be GU.

 

[JohnW2]

I think it should be G5.3 not GU however many adds do call them GU. Only the bayonet pins should be GU.

If I recall correctly, it's a bit more complicated than that - I have a feeling that the "U" refers to there being some means of 'mechanical retention', not necessarily a bayonet (i.e. it could be provision for a spring clip). I don't know what "X2 and "Y" mean (as in "GXxx and GYxx).

For what it's worth, although one sees lamps/bulbs with, for example, G4 and G9 basis, I don't think I've personally ever seen one described as G3.5 (although there are obviously countless GU3.5 ones).That tends to suggest that GU3.5 may well be correct.

Kind Regards, John

 

[EFLImpudence]

Indeed.

I cannot find a definitive description of all the types - perhaps no one knows.

Wikipedia says the G stands originally for glass.
No second letter or U, X, Y or Z is the base shape - but doesn't say what shapes.

So, it would seem there could be G, GU, GX, GY or GZ in all sizes.
They may not, of course, all be manufactured.

To differentiate between push-in pins and twist-lock pins it is also really necessary to include such in the description.
That is GU10 which we think of is actually GU10 twist-lock as there could be a GU10 push-in.