Recommended 12v transformer for halogen lights

[James_H]

I will be putting in 6 x 50mm individual halogen downlighters, each with 35w bulbs and switched by a single MK 'LV' dimmer.

The general consensus on this forum is to have more than one transformer in case of failure of one. I plan to have two as I cannot see the benefit of having one for each. Greater reliability from one for each is only of benefit if life is three times as long.

Torodials are pricier so an electronic 'transformer' will do that can be fed through the light holes if replacement is needed.

The general view is to avoid the sheds as always . At least for the value packs with a few fittings and a cheapie transformer. But is there any particular brand of transformer to go for?

TLC do a premium transformer rated 0-250w. They also supply an Intram Barwell 20-105w, but being at the top of the rating and considering a bulb could be upped to 50w, it might be worth having three of these. Any preference between the two?

Thanks.

 

[Lectrician]

I would go with JCC

I can pick up JCC 50VA trannies for around £3 plus vat. A 150VA is almost 3 times the cost!

If you do have 1 tranny feeding more than one light, DONT daisy chain the lights, put the tranny in the middle, and feed out to the other two with some decent sized cable. How far from the tranny are the lights to be??

I would strongly urge you to consider using individual trannies, wiring is easier, easier to change to different fittings further down the line etc etc.

 

[ban-all-sheds]

I believe that IBL are also pretty good.

 

[ebee]

1 TX per lamp for me every time

 

[Adam_151]

With one transformer per light, is there an issue that if the lamp fails, and you neglect to replace it for a few days, that the transformer won't like zero load on it and fail?

I notice the OP quotes two transformers, one rated at 0-250w, and one at 20-105w, I guess with one per light, you should make sure the ones you use are zero and up?

 

[Lectrician]

The transformers shut down on no load, or too much load, and when they get too hot.

 

[baldelectrician]

I only use JCC, never have any failures and install ont tranny per light.

No revisits and no hassle.

 

[James_H]

A belated thanks. I just need a find a public-friendly wholesaler or retailer for JCC.

There was one other issue I forgot at the time. The MK 4501 LV dimmer (single module grid dimmer) recommends a maximum of three transformers so I may stick to that limit.

If I can't find JCC, IBL have a max 0.5m from transformer to lamp that could be impactical for me with multiple lamps. Aurora have been mentioned positively in the past with Screwfix and Alert selling some of their range and they have a longer 12v length limit.

Other than have a status LED, what does a self-monitoring transformer do over a more basic one?

James

 

[ban-all-sheds]

I could just about conceive of a power supply which monitored the starting surge of the load, and by comparing it to the steady-state load, determined how long the cable was and adjusted its output accordingly to compensate for volt-drop.

But I don't think it would work in practice.

So I don't see how any power supply can support a longer cable than any other. They put out 12V - the rest is just Ohm's Law.....

 

[baldelectrician]

I buy JCC trannys at local wholesaler, phone JCC and ask for a local stockist.