Postby witsend » Wed Jun 18, 2008 11:58 pm

As a newbie, I read with interest the often negative remarks about LV fittings. It was helpful [though I'm committed in my property to over 40 of them!] Anyway my question concerns a very attractive contemporary design lighting track that is fixed to the kitchen ceiling above an island unit.

The track comprises [i] a track with two strips of metal about 2 metres long separated by plastic [this track carries the 12v supply]; [ii] ceiling fittings into which the track clips and allow it to be installed as an attractive elongated S-shape over the island unit; [iii] 4 fasten-on downlighter fittings which are rated to take standard 35w LV halogen lamps; [iv] a metal finished cylindrical casing screwing to a ceiling plate; two metal fittings emerge at the bottom of the casing to deliver 12v across the rails; inside the casing is heavy fused square transformer rated at max 150 VA which has 4 screws which offer up through the transformer and hold it to the ceiling plate.

This has been an attractive design idea that has worked well for 7 years [couple of fuses went, that's all]. Now however the transformer appears to have gone kaput and a plastic thread fitting has failed [possibly due to heat]. The product by Eglo is obsolete, no spares [isn't this always the case?] and we have searched extensively without finding a similar product with good design.

Sorry for all the detail. My query: As the fitting carries a load of 4 x 35w = 140w, is there any way in which I can dispense with the Orientronic transformer that weighs in at 2kg [!] and simply use one or more lightweight transformers to deliver the power that could sit above near the joist to which the ceiling plate is attached. I'm not sure how to do he necessary calculations but it seems as if I'm dealing with a fitting equivalent to < 2.5 standard downlighters and maybe it can be dealth with similarly and without the heavy transformer. I've looked for its replacement but that has been a blind alley.

I hope no bright spark will suggest a 240v pendant as the style fanatic to whom I am married [currently, high voltage!] won't tolerate anything she considers naff. It's not the £200 we spent on the original fitting, we simply can't find anything comparable.

Hope you guys can help technically and make sure I don't burn down the house trying to save this fitting.
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Joined: Wed Jun 18, 2008 11:17 pm


Simply Build It

Postby ericmark » Thu Jun 19, 2008 8:58 am

Unless your using a dimmer switch the power supplies for 12 volt lighting are interchangeable. There are basically two types.
1) The transformer heavy and does not correct voltage output tied to input and can work with no lights connected.
2) The inverter much lighter and will in some cases auto correct voltage so bulbs last longer has a range rather than maximum and often can not be run with no bulbs.
Both types will have maximum voltage. Second will be cheaper to run. Often both are referred to as transformers the second does contain a transformer but it works by turning AC to DC then back to AC at very high Hz then transforms to low voltage it then samples the low volts and alters the parameters of electronics to keep the correct voltage.

Postby witsend » Fri Jun 20, 2008 12:31 am

Thanks ericmark. The light fitting I described was not supplied for dimming so I'll exclude that complication.

I didn't know about inverters. Googled these and found that nearly all sites only offer products sold to caravanners, boat people so 3-pin plug appliances can be run from a 12v battery- they usually show the 3-pin socket in the pics.

I did find a unit on ebay that delivers 150w at 12v from 240v source. This is quite a large box 230mm long by 110mm wide so I'd have to lift a floor board and install it above the ceiling plate - not like the usual 12v LED transformer that will slip into a quite small hole in the plasterboard.

Can anyone confirm that the only suitable units are this large or do any miniatured types exist? Also are they fuse-free? I wouldn't want to have to lift the boards every time a fuse pops.
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Joined: Wed Jun 18, 2008 11:17 pm

Postby ericmark » Fri Jun 20, 2008 9:03 am

Ups! That must have caused confusion. Transformers listed as Electronic are inverters. An example Technical - Electrical Data from Osram
For a “HTI DALI 150/220-240 DIM UNVIâ€

Postby witsend » Fri Jun 20, 2008 12:54 pm

Thanks for that clarification Eric, it made A BIG DIFFERENCE!

May I just ask you to look at TLC - Premium Transformer ( 0w - 250w ) because this product is small and appears to handle 250w i.e. I assume I could hang up to 5 x 50w LEDs rather than be limited to 4 x 35w as in the original configuration. Am I right?

It begs the question why on earth was the original unit designed with a 2kg transformer, though I bought the design 7 years ago and it might have been designed 10 years ago. Not sure how long these ETs have been about.

I have never touched the exposed track when the lights are on but presumably with say 12v x 20 amps it would be quite a kick. It sits 6" from the 7ft 6" ceiling and presumably one would need to apply finger and thumb across the two track section that are separated by plastic.

Thanks, I'm learning and hope not to be at my wits end for much longer.
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Joined: Wed Jun 18, 2008 11:17 pm

Postby witsend » Fri Jun 20, 2008 10:16 pm

Thanks for the clarification in your e-mail. I have used tlc-direct before.

Am I right in thinking that this will support 4 or 5 50w LEDs on the track I described [currently 4 x 35w used]?. Will easily slip into a hole above the light fitting.

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Joined: Wed Jun 18, 2008 11:17 pm

Postby ericmark » Fri Jun 20, 2008 11:21 pm

I did find that advert seems OK to me for as you say 5 x 50 watt lamps although I think you will find LED versions are more like 5 watt max the 50 watt type are quartz Halogen type. As to the rails you will not get a shock as although high amps the volts are so low. There is a point with 20 amps flowing you need at least 2.5mm cable and if originally designed for 4 x 35 watts the cable may not be thick enough.

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