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Ceiling light replacement - transformer question

Posted: Sun May 13, 2007 9:55 pm
by chrisquy
Advice needed please...!

Am currently in the middle of replacing a ceiling light. Have read through the topics in the forums but nothing seems to quite match. Apologies if a repost.

Currently have a conventional ceiling rose in a looped circuit without a separate junction box. Am looking to replace this exisiting rose with a lighting system that involves a transformer being secured to the underside of the ceiling as part of the feature. (Suspended halogen bulbs as part of a insulated plastic cable system stretched across the room, secured into opposing walls, transformer wired into the insulted cable through use of special fixings.)

The fixing instructions included with the product, only give guidance for a system with a separate junction box. The transformer itself has an earth, a live and a negative wired into a block, the idea being that you would then wire in the appropriate wires from the ceiling side (a process that involves passing them through a hole in the middle of the transformer before mounting to the ceiling.

The problem I have with my circuit is that all of the wires coming through the hole in the ceiling to the existing rose will not fit through the hole in the transformer - even if they could, I'm not sure how I would wire into the block from the light.

My question is; would it be possible to instead, keep the existing ceiling rose block wired as is, take the brown and the blue from the exisitng light flex, remove the bayonet holder and wire these (passing through the transformer) into the block provided with the new fitting? As for the earth, would some additional earthing cable routed from the existing rose (via the same hole through the transformer) to the earth in the new block suffice?

If so, I could then insulate the old rose with electrical tape, push back through into the ceiling, leaving the area smooth to flush fit my new transfomer, fully wired up.

Any thoughts? Would appreciate any responses - apologies for the length of the post or if my descriptions are not quite clear! Thanks in advance.

Posted: Mon May 14, 2007 9:01 pm
by sparx
If you can keep entire rose complete with cover, then flex +earth through would be ideal answer.
If rose requires too large a hole to make good after then try to get a thing called 'chock box' which would go around the connecters and still give enclosure reqd. by regs,
Regards SPARX

Posted: Mon May 14, 2007 9:27 pm
by chrisquy
Sparx - thank you.

Just to clarify - If I re-assemble the rose as-is back up in the loft above the ceiling, put the old rose cover back on - this will be enough to insulate correctly, and there will be no problems with wiring a new earth wire from the existing earth block in the old rose, down through the transformer, wired into the new block within the new fitting?

Posted: Wed May 16, 2007 10:57 pm
by sparx
Yes I think that would be satisfactory, especially if you use 3 core flex from rose to tranny, regards SPARX

Posted: Thu May 17, 2007 11:51 am
by chrisquy
Brilliant.

Thanks very much for the help - great service.

Chris