downlights MR16 to GU10

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Hi

I have 25 MR16 Aurora fire-rated downlights like these in a few downstairs rooms, installed by an electrician during building work 5 years ago. All wired via small black JBs and Aurora transformers.

I'm converting them all from 50W halogens to 5W LEDs. I've had some false starts with MR16 LEDs (existing transformers causing LEDs to fail) so I've decided to remove the transformers and convert them all to GU10 - new flex from JB to fitting, then new GU10 bulb holder.

The current fittings aren't earthed and aren't marked as double insulated as far as I can see). Should they be earthed now that they will be mains voltage? If so, how - is there some kind of mini earth clamp I could use? The fitting wiring is in a standard small black plastic box completely isolated from the metal fitting. I know I could replace the fitting entirely, but that would make the job more expensive than it's worth.

Cheers
 
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You must read the installation instructions.
http://assets1.auroralighting.com/web/sku/1636/general/instructions.pdf

Look at the words in the GENERAL section

That will tell you that Aurora says that these Class III fittings :
1. Must be used with a SELV transformer only and
2. Must not be connected toi a mains supply.


If you want to go ahead and go against the MIs then its up to you.


PS Fig 2 shows what to do with the earth connection,……….
 
OK thanks.

But there doesn't seem to be any physical difference between my existing LV fittings and the 240V equivalents e.g. here - except for an earth connection.

So I think that answers my question, unless anyone can tell me that the earth isn't required?
 
The fitting itself does not need to be earthed.

However, the earth connection must be made from the source (switch?) through every light fitting to the last one. That is what the "earth loop" connection is for.
 
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PS Fig 2 shows what to do with the earth connection,……….
The fitting itself does not need to be earthed. ... However, the earth connection must be made from the source (switch?) through every light fitting to the last one. That is what the "earth loop" connection is for.
Is there not some potential confusion here? The required 'earth looping', as illustrated in Fig 2 of the MIs, is on the mains side of the transformer. There is no earth connection even to the primary side of the transformer, let alone to the light fitting, so the above statement about looping the earth "through every light fitting to the last" is not really true - or (if you count the {separate} transformer as being part of the 'light fitting'), at least potentially confusing/misleading.

Kind Regards, John
 
Ah apologies. The Aurota diagram does show what is necessary on the mains side of the transformer. This same wiring would be needed at some point(s) should the downlights be "converted" to use GU10/LED lamps.

I doubt that the downlight will have any provision for an earth loop, having been designed for just two connectors (ie the 12v output from a transformer)/.

Just another challenge for our OP should he decide to convert his 25 downlights.
 
Ah apologies. The Aurota diagram does show what is necessary on the mains side of the transformer. This same wiring would be needed at some point(s) should the downlights be "converted" to use GU10/LED lamps.
Exactly.
I doubt that the downlight will have any provision for an earth loop, having been designed for just two connectors (ie the 12v output from a transformer)/.
Indeed. In fact, not only would one not expect any provision for an earth loop at the (SELV) fitting, but could it not be argued that it was actually undesirable (or even 'not allowed'?) to introduce the installation's earth into a SELV environment?

Kind Regards, John
 
It would seem even if not used at the lamp since 1960 we have to provide an earth to every lamp.

The rules pre 1960 did allow no earths to lamps but then it was realised class II could be easy changed to class I and the regulations changed.

It seems strange in the 54 years people could not get there head around the change.

We still have people posting stickers on consumer units warning of the problems of no earth but to start a new set of systems without that earth is unforgivable.
 
It would seem even if not used at the lamp since 1960 we have to provide an earth to every lamp. The rules pre 1960 did allow no earths to lamps but then it was realised class II could be easy changed to class I and the regulations changed.
Has that ever applied to ELV lamps?

Kind Regards, John
 
I read GU10 and yes I agree this is a connection and does not mean the lamp is 230 volt you can get 12 volt GU10 but I has assumed 230 volt. Sorry this is clearly wrong there is nothing to stop swapping MR16 to GU10 and still have a 12 volt supply sorry.
 
Is that not what was meant?
so I've decided to remove the transformers and convert them all to GU10 - new flex from JB to fitting, then new GU10 bulb holder.
Indeed. I think this discussion is getting a bit confused. Yes, I think that the OP currently has 12V GU10s (with transformers) but wishes to remove the transformers and use 230V GU10s instead. This is why the issue about earthing has arisen - the fittings intended for 12V had no provision for earthing, but probably need it if they are to be used for 230V lamps. ... or maybe it is I who is confused or who is misunderstanding!

Kind Regards, John
 
Although I will agree it is wrong as MR16 is the size of reflector and GU10 is the way it connects I think most think of MR16 being GX 5.3 and 12 volt and a GU10 as being 230 volt.

With the introduction of LED the main reason for 12 volt has gone and to convert to 230 volt makes a lot of sense.

However the lack of an earth conductor is really a problem as on one hand most GU10 fittings do not have any connection for an earth but BS7671 says the earth should be available even if not used.

In the 1960's when the rules were made there were no GU10 fittings but also a GU10 could be used in a class I unit as well as class II so really earth needs to be there even if not used.

It is unlikely with RCD protection there would ever be a problem with the lack of an earth but no one would dare to suggest not providing one.
 
Thanks all

Just to confirm, the conversion is from 12v MR16 halogen 50W to 240v GU10 LED 6W

After a lot of trial and error, this bulb from LEDHut is the closest match I can find for a 50W halogen - at 6W that's an 88% electricity saving for the same amount of light. I got these for about £7 each with a discount code - should pay for themselves in max 12 months, depending on usage.

On closer inspection, the Aurora fittings are clearly universal 12v/240v:
- the black cable box is big enough for a 3-terminal block
- there are 3 cutouts on the lamp side of the cable box
- there's a pre-drilled hole on the vertical arm, to fit an M4 earth terminal screw
Every picture I can find online of these and similar fittings with wiring shows an earth cable connected to the vertical arm.

So, here's a before-and-after picture of what I'm proposing to do.
(No heat sleeve on new GU10 bulb holder wire - teflon insulation rated to 180 degrees C.)
Am I doing this right? Would appreciate any advice before I crack on with the other 24 fittings this weekend!



Cheers
 

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