Halogen downlights

norm · #1 28-02-2006, 09:41 PM

Hi,

Just wondering if anyone has any tips for my dilemma. Our house uses 12v 50w 60 degree halogen downlights in various rooms. They've been installed for just on 3yrs and ocassionally one needs replacing. However 3 particular ones have just given me grief over the last 6 months. What happens is that the bulb goes out, after a few tweaks they'll come back on, only to later go out again. Even with a new bulb it may last a few days or weeks before the same thing happens. The bulbs seem ok, except their black/sooty on the contact pins.

With one set, I've successfully replaced the transformer, lead and bulb and its been fine, but the other 2, even after replacing the whole lot, they still give me grief.

I'm borderline going nuts

getting the ladder each time to fix it. Does anyone have any ideas? Do you think getting high quality transformers will do the trick (it will mean a visit to the roof).

btw: I spoke to a Sparkie once and he just strugged his head and said its one of the downfalls with halogens.

Thoughts appreciated!

acropolite (Phil) · #2 28-02-2006, 09:58 PM

You can get downlights (in exactly the same size) that run from 240V and require no transformer, both in Halogen and compact flouro, maybe with those you'll get a better run.

RAJAH235 · #3 28-02-2006, 10:17 PM

Norm, sounds to me like the base assembly, (pins/contacts), are of an inferior quality. The halogen globes run extremely hot & if the hardware ain't up to it.....
The 'black/sooty' appearance means that the globe connections are not tight, eg; loose pins in the ceramic base, which causes a high resistance connection & generates more heat........which in turn will de-temper the metal base pins even more......
Replace the bases & globes, with better quality ones n prob should disappear.
HTH.

L.

chunkylad (David) · #4 01-03-2006, 02:29 PM

Quote:

Originally Posted by RAJAH235

Norm, sounds to me like the base assembly, (pins/contacts), are of an inferior quality. The halogen globes run extremely hot & if the hardware ain't up to it.....
The 'black/sooty' appearance means that the globe connections are not tight, eg; loose pins in the ceramic base, which causes a high resistance connection & generates more heat........which in turn will de-temper the metal base pins even more......
Replace the bases & globes, with better quality ones n prob should disappear.
HTH.

L.

As Rajah says, with any loose connection, especially applications with high current and/or (as in this case) are subject to heat, thermal runout occurs. this is where resistance causes more heat, more heat creates higher resistance, and so on until something burns out.

We have just finished a major reno at our place and have installed around 2 dozen downlights. Originally I wanted the 12V type, but my sparkie talked me out of it,

saying that the 12V transformers have only a short-ish life expectancy. I didn't fancy scrabbling around in my cramped cieling space in a tropical summer to replace them, so we went 240V with great success.

Good luck on the repairs to your system. Hope you get them all working again

Cheers

Jonathan · #5 01-03-2006, 03:21 PM

A mate of mine had a pub for a while with a few dozen halogen lights in it. He was changing a few globes every week. Judging by what I've seen, I'd do what RAJAH235 said and replace the globes and bases with high quality ones.

acropolite (Phil) · #6 01-03-2006, 07:33 PM

An added advantage of the 240V type is that they are a slightly warmer colour and are more easily dimmed.

cjmarsh81 · #7 01-03-2006, 09:16 PM

I think it would be the sockets, rather then the globes themselves. They run a fair amount of current and the terminals will get hot and go black if they are not connecting properly.

Another idea. Jaycar Electronics have LED replacements for halogen downlights. They have taken high-brightness LEDS and put them into a down-light housing. Should be fairly bright and use less current. They are expensive, but you should only have to put them in once. LED's should last virtually forever.

ving (David) · #8 02-03-2006, 01:38 PM

seeing that you say you are ging thru globes maybe its something to do with the socket in which they are being placed... or wiring... i dont know...

norm · #9 03-03-2006, 11:39 AM

Hi All,

Thanks for the feedback. At the moment they haven't decided to switch off, so with the old saying 'if it aint broke......' However WHEN they do I'll try some of the recommendations. Probably the socket is the 1st thing I'll try as it will be the cheapest. I like the LED idea, but they're not cheap at around $40 bucks a pop. Also, the white light will make it look a tad sterile - maybe they come in that warmer incandescent color ?

One thing is for sure the heat generated is is huge. Found out the nasty way when I had a momentary lapse of concentration - ouch!

Certainly anyone contemplating getting them, do some research there are pro's (looks nice) but just also some cons.

RAJAH235 · #10 03-03-2006, 06:25 PM

FWIW. These fittings may appear to be "the best thing" etc etc, but the amount of heat they generate in the ceiling space & in the rooms, is not taken into acct when buying.... not too efficient either... IMHO.

L.
ps. better off with 'normal' 240 volt incandescent globes/downlights & a dimmer, or change to the compact fluro's.

cjmarsh81 · #11 03-03-2006, 06:28 PM

Fluoros, way to go. I can't stand yellow lights. That is why my bedroom is lit up with white Leds.

RAJAH I agree. There is too much heat generated in the globe itself, and also in the transformer sitting in the roof. I used to work for an OptusWorld store that had downlights running 24x7. The transformer kept going into thermal shutdown every 3-4 hours and then would turn back on when it had cooled a little. I think they are a fire hazard and should not be allowed in homes with insulation in the roof (insulation I think is a legal requirement in all new homes).