cabling for ceiling downlighters

Still struggling with deciding how to update the ceiling lighting.

If I go for low volt downlighters, is it normal for each downlight unit to have its own separate transformer?

If so I presume normal 1.0 or 1.5 mm2 cable can be daisy chained to each outlet? & that then gives the flexibility to allow switching between LV & HV units later?

Or am I misunderstanding something?

Any experiences of fitting & cabling downlighters would be much appreciated.

TIA

Reply to
jim
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You can get both sorts - either with built-in individual transformers, or with a separate one serving several lamps.

The ones which I installed about 8 years ago had separate transformers (I'm not sure that the other sort were available at the time) and the ones which an electrician installed in our refurbished kitchen last year had individual built-in transformers.

That's precisely right - you just feed mains to each lamp's transformer, so you can mix and match. Having experienced both sorts, I would certainly go the individual transformer route in future. With the other route you need fairly hefty cables between transformer and lamps because they are carrying much more current and you can't afford any appreciable voltage drop. You also need to be able to access the transformers via a lamp hole in case they need replacing - but with the other sort, the transformer comes out with the lamp.

Reply to
Roger Mills

Not compulsory but usually easier nowadays.

Look for trafos with loop through, set of mains terminals in and out, makes daisy chaining easier.

It keeps cable size under control and no cost adavantages any longer to single large transformer.

Sounds like your understanding is good, you`ve already made right choice with LV arther than GU10 ;-)

Cheers Adam

Reply to
Adam Aglionby

Not compulsory but usually easier nowadays.

Look for trafos with loop through, set of mains terminals in and out, makes daisy chaining easier.

It keeps cable size under control and no cost adavantages any longer to single large transformer.

Sounds like your understanding is good, you`ve already made right choice with LV arther than GU10 ;-)

Cheers Adam

I would go for mains units then you can change the bulbs for led ones when the prices come down. Good ones are around £15.00 each at the moment. Saves the cost of the transformer etc. Just need to do your sums !

Reply to
John Smith

4x the number of transformers means 4x the failure rate

NT

Reply to
NT

Not a satistician , but sure there someat wrong with that.

Besides good trafos, Mode and IBL are good, will last many years.

Cheap trafos are 1.99 so odsd failure few years perfectly acceptable.

Cheers Adam

Reply to
Adam Aglionby

Its simple statistics. Same failure rate for each one, 4 times the failures per given time, equals 4x the failure rate.

NT

Reply to
NT

Thanks for the explanation, see where your getting at, but MBTF I think would be to 50% fail which would leave half working with 4.

At least a single failure won`t leave you in the dark with multiple trafos ;-)

Cheers Adam

Reply to
Adam Aglionby

I reckon 2 or sometimes 3 transformers is about ideal

FWIW, the comparison I'm making is one failure per MTBF compared to 4 failures per MTBF.

NT

Reply to
NT

On 26 July, 22:59, Adam Aglionby wrote: ///////

Many thanks for most informative replies,,however

What is a 'trafo'? please 'scuse my ignorance but I read it at first as 'transformer' but not sure....

Also any (web) pointers to suitable units. The only one found so far with fittings & bulbs which appears in keeping with the various B. Reg rules is the TCL

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> Cheap trafos are 1.99 so odsd failure few years perfectly acceptable. web pointer to 1.99 units would help & also perhaps throw light on meaning of 'trafo'

TIA

Reply to
jim

transformer

Reply to
NT

Is this on..

Reply to
Adam Aglionby

Sorry about other post google groups was having an off day

Yup, you read it right, its just my lazy typing.

Usual suspects , Screwstation, Toolfix, TLC, local electrical wholesalers.

Recession converts wholesalers view from `who`s calling.....?` to ` We welcome cash sales` :-)

Local independent wholesaler had a box of 10 for 19.99 + VAT.

Screwfix have a box of 10 for 28.90 or so.

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cheap trafos are for hit and run developers, its worth spending extra couple quid a point of you live with it.

Cheers Adam

Reply to
Adam Aglionby

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