Replacing downlighters

[GB]

MIL had about a dozen of those 12v halogen mini downlighters set into the living room ceiling. (Oh, and another dozen elsewhere!) We are going to have to replace them all, because she smoked heavily, and they are crusted in nicotine. AFAIK, they all have individual transformers, several of which are faulty. Others hum.

My preference would be to rip the lot out and replace them with GU10 (?) mains powered bulbs/fittings that will fit in the same size holes. The only thing that stops me is a worry that the cables may not be long enough, particularly if it turns out that one transformer served several of the 12v lamps.

Is it going to be far, far simpler just to replace like with like?

We are going to rent her place out, so I won't be paying the electricity bill. :)

[ARW]

Yes, and even cheaper to wash the downlights with a bit of "flash with bleach".

I suspect that you are going to have to replace a couple of transformers or maybe a couple of MR16 lamp holders (another common cause of 12V lights not working) before you rent. Take the time to see if it is possible to swap the lights for 230V GU10s before swapping these.

The humming ones:-) I wonder if it is a toroidal transformer feeding several lights. Any dimmers in the house?

[GB]

We are throwing out all the carpets, painting all the walls with 3 coats of paint, throwing out all the furniture, and washing down all other surfaces. All in the hope of ridding the place of the tobacco smell. The downlights are a minor expense, in comparison, and I doubt that we could clean them well enough.

So, check that there is a mains cable to each lamp, and it's long enough. Presumably, I should expect two cables to each transformer at the moment, assuming it's daisy-chained?

No, I don't think so.

[Johny B Good]

I've got four 35W 12v downlighters (not my choice!) in our downstairs shower/toilet as a result of a refurbishment some 3 or 4 years ago. I've yet to experience "The Joy" of changing a lamp.

Most likely on account of them each being fed via their own individual electronic 'transformer' (12v 60W max smpsus which limit the inrush current to 5A max on switch on - direct connection to a 12v fully charged car battery would most likely result in an inrush current of circa 30 amps! - for a 240v lamp, an inrush current equivilent of 1.5A versus 150mA running current).

What I'm trying to stress to you is the importance of _NOT_ using

240v GU10 lamps if you want to avoid the grind of replacing a lamp or two every month or so after the initial 'Honeymoon' period has expired, some 6 months or so down the line.

Even using the old 50Hz mains transformers is better than using 240v GU10 lamps. If you must update the system, I'd recommend a modern 12v lighting system using smpsu technology in place of 50Hz 12v mains transformers. Only a fool would use 240v lamps in this application.

[meow2222]

Chuck them in the dishwasher.

NT

[ARW]

That is a possibility. Or there could be a junction box somewhere splitting the 230V into multiple transformer feeds. If the cable is reachable but not quite long enough to fit to a GU10 lamp then use a small junction box to extend the cable.

Have fun

[Roger Mills]

On a more or less related subject, I have 12 50W downlighters in my lounge - which I installed about 12 years ago. These are in 3 groups of

4, with each group running off an individually switched transformer. The output from each transformer is a short 2.5mm cable to a junction box, and then individual 1.5mm cables from the junction box to each lamp. the lamp fittings themselves have little 2 gang choccy blocks to join the incoming cable to the short heat-resistant cable which terminates in a bulb holder.

I've had several failures fairly recently, after none at all for the best part of 12 years. In each case, the bulbs have still - amazingly - been ok, and the failure has been that one gang of the the choccy block has 'caramalised' due to overheating. I assume that the screws have become slightly loose - despite being fully tightened at installation.

I have replaced the offending choccy blocks and re-made the connections, and the lamps are working ok again. But the thought occurred to me to wonder whether I would be better off doing away with the choccy blocks and using crimps instead. The feeder 1.5mm cables are solid core whereas the short heat resistant cables are stranded.

Any comments?

[robgraham]

GU10's are the spawn of the devil and are notorious for bulb failure. Just do not go down that route.

And having suffered the same problems as Roger - the 12v halogen MR16 ones will be taking a fair number of amps which on the basis of I^2 x R generate s heat in quantity if there is the slightest resistance - I changed over to LED bulbs. If you get the COB ones they have a good spread angle and are the way to go IMO - low failure rate (wouldn't be difficult comparing with GU10's), low power consumption and certainly cheaper than GU10's over a yea r or so.

Rob

[Kostas Kavoussanakis]

Just to state my experience: I have lots of 240V GU10s and they do not fail. I have a box of replacements which I bought 7.5 years ago when these were installed, and after an initial replacement of 2 or 3, it just won't run out. I have a dual dimmer switch on them (one with 4, one with 8 bulbs), which may help.

Re LEDs, I recently got Philips Masters with a claimed 35 deg spread (never seen wider); they create nice cones of light and plenty of darkness around them, compared to the previous 20W 240 Halogens. I am too stingy to put them back on since I paid for the 4 LEDs, but I am leaving the remaining 8 on Halogen; I generally run them less often, but when I need them they do the job, unlike the LEDs.

YMMV.

Cheers,

Kostas