LED downlighters - 12V or 240V?

Think I've finally convinced myself that I'm going to swap over from halogen downlighters to LED ones.
Forgetting for a moment whether downlighters a fundamentally a good idea
or not (for various reasons these are staying, end of!) my question is whether to go for 12V or 240V ones?
My current halogens are 12V, but AFAICS I'll still still need to replace the PSUs for some LED-compatible ones. On the plus side, I can re-use the existing downlighters; they are quite a bit larger than modern ones (12V or 240V) so replacing them would be something of a ball-ache in that I'd have to *reduce* the size of the holes in the ceiling.
So, is there any compelling reason to swap to 240V?
Thanks
--
David

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Lobster wrote:

The need not to use a transformer/LED driver is a bonus for the 230V LED lamps.
All you need is some GU10 lampholders, some GU10 LEDs and to remove the 12V transformers.
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Adam



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On 04/05/2013 17:17, ARW wrote:

Sure, I get that - but the need to fill in and recreate the holes in the ceiling really stacks against the need to buy new transformers... what I was getting at was the pros and cons of the two systems *in practice*, ie once they are fitted, and up and running...
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David

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The 12V ones will be slightly more efficient. LED lights are driven from a constant current source, so some type of voltage stepdown system will be needed in the 240V version before the constant current regulator - or else it will dissipate huge amounts of power (Power = volts * amps etc ....). Any type of voltage reducer (transformer or capacitive series element) will dissipate a small amount of extra power compared with the 'straight in' low voltage type.
Andy
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Andy Bartlett wrote:

Or a constant voltage source.
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Adam



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LEDs *should* be driven by current, not voltage.
MBQ
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Man at B&Q wrote:

So why do they sell constant voltage drivers?
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I don't know, but LEDs are current driven devices.
MBQ
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Probably talking at cros purposes.
The LED lamps will have extra circuitry, since no LEDs actualy run on 12V.
MBQ
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Not if it's a switch mode "stepdown system".

ow

And where do you think the 12V comes from?
MBQ
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Lobster wrote:

I thought you were keeping the existing downlights and just changing the lamps.
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On 05/05/2013 08:58, ARW wrote:

Sorry maybe I waasn't clear then. I'm definitely keeping *downlighters* as such, ie as a form of lighting (SWMBO has told me so); it's a case of whether to go to 12V LED (ie which would mean keeping existing downlighters and just swapping lamps and transformers) or to 240V LED (meaning swapping lamps and downlighters, plus the ball-ache aspect of having to form smaller holes in the ceiling). From what I'm reading there doesn't seem to be any justification for going 240V?
--
David

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Lobster wrote:

Why does swapping to 230V mean you have to buy new downlighters?
You just replace the transformer with
http://www.wholesaleledlights.co.uk/5-pack-gu10-wire-holder.html
and fit 230V lamps.
Or am I missing something?
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On 05/05/2013 09:58, ARW wrote:

No you're not - I am!
Hadn't realised that you could convert 12V ones to 240V ones so easily - pretty obvious with hindsight I suppose! So that's good - either option is equally on the table. Still not sure which to go for TBH!
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Lobster wrote:

As I only fit the 230V LEDs (unless it's under cupboard/specialist stuff) then I can offer no opinion as to which is your best way forward. I just gave you the option to fit either lamp in your downlights.
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On 06/05/2013 16:01, ARW wrote:

OK, reckon I'm going for 240V LEDs...
However, I note that almost all these 240V connectors/adapters (including those in the above link) make no provision for a CPC; although there are a few around which do so - eg: http://www.ebay.co.uk/itm/261212463223
What's the regs and/or best practice on this issue, given that these are always exposed metal downlighters? Most of the downlighters sold for 240V use that I can see online don't appear to be earthed.
In my own case, I have particularly low ceilings and can easily change the downlighter lamps while standing on the floor (ie including the potentially wet, tiled kitchen floor) - is that what would make a difference?
Thanks
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David

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Lobster wrote:

It depends on your existing downlights.
Any chance of a couple of photos of your existing lights? And preferably one that has been removed so I can see the back of it. It may not need an earth.
BTW did you notice that it's 230V not 240V in my replies?:-)
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On 11/05/2013 19:37, ARW wrote:

Here you go:
http://imageshack.us/a/img259/1884/img0071dd.jpg
Must admit I thought mine had that little metal strip connecting a terminal block to the downlighter (like in the above ebay link), but evidently not; must be in other ones I've wired up elsewhere. Is that what makes the difference earth-wise?

<Visits http://en.wikipedia.org/wiki/Mains_electricity> - Ah OK, 230V it is, then!
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Lobster wrote:

A tricky one to call. The leads for the 230V GU10s are not double insulated BUT they are not passing through the metal fitting.
I would fit the 230V LEDs without worry if they were my lights.
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On 12/05/2013 16:42, ARW wrote:

Thanks Adam - am going shopping!
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