Spot lights intermittently coming on and off

ey143

I had a loft extension done over 10 years ago. We put 6 spot lights into the ceiling (I think each have their own individual transformer). We also have one dimmer to control the brightness.

Since that time, one by one, they started going wrong such that one would hardly come on and we would have to turn the lights on and off many times to get it to come on. Now the others have started doing this so we only have 2 spot lights properly working and we have to keep switching it on and off hoping that some of the others might come on.

Even when they bad ones are working, the bad ones would now and again switch off. The bulbs all seem fine. Is it the transformer that has gone for each of them - is it expensive to sort out and do I need to call an electrician or can I do it myself?

Thanks.

almillar

I assume we're talking about halogen spotlights - MR16 or something?
I've had one transformer fail in my house and it went the same way - bulb just randomly going or flickering every so often, which got more and more often. Sounds like you may have more transformers to buy, or maybe convert to GU10, which would mean the transformer is built into the bulb unit.

zax47

almillar wrote: »

I assume we're talking about halogen spotlights - MR16 or something?
I've had one transformer fail in my house and it went the same way - bulb just randomly going or flickering every so often, which got more and more often. Sounds like you may have more transformers to buy, or maybe convert to GU10, which would mean the transformer is built into the bulb unit.

GU10s are mains bulbs, not 12V, no transformer "built in" as none is needed!

Myself I'd also be suspecting the dimmer. Swap it for a normal switch and see if the problem goes away - 1st thing I'd do if I was diagnosing this. I'd also be checking all the connections if the issue is intermittent.

Trannies are dirt cheap now (around a fiver for a 20-60 VA {Watt} "electronic" transformer), but are you sure it's wired with one per bulb? When they were much dearer we used to fit 1 larger capacity tranny to drive 4 or 6 bulbs.

ey143

I remember being advised to buy one transformer per bulb even though it would cost me more - I think it was for this precise reason it was recommended.

Thx.

zax47

ey143 wrote: »

I remember being advised to buy one transformer per bulb even though it would cost me more - I think it was for this precise reason it was recommended.

Thx.

That's certainly the "best" way to do it, and more cost-effective nowadays. It's easy and cheap enough to check the dimmer though, just swap it for a normal on/off switch.

Another common issue with 12V MR16s relates to the fact that they fit just by pins and get quite hot. This loosens the connection to the pin through constant heating/cooling hardening the sprung fitting inside. I went to a kitchen with 8 MR16 spots with the same problem as yours, some lights off, some on, always changing. Had been in about 12 years. Trannies were fine so swopped out all the connections to the bulbs. Voila - problem solved. :j

You can buy them at an electrical wholesalers or even the ubiquitous eBay;

http://www.ebay.co.uk/sch/i.html?_trksid=p2050601.m570.l1311.R1.TR1.TRC0.A0.Xmr16+connec&_nkw=mr16+connector&_sacat=0&_from=R40

almillar

Sorry zax, I think I'm getting confused with LEDs and CFLs, which I believe do have need transformers, either outside or inside, whereas halogens don't. Is that right?!

ey143

Hi

Thanks for the reply and sorry for the delay. Yes, the link you posted, I remember the fittings look like the two holes in the ebay photo. I remember having broken some of the halogens in the past trying to fit them into the socket as it was difficult to fit or remove - probably because of the heat/contraction that you mention. Two questions though:

Is it relatively easy to replace a dimmer switch with a light switch?
Is it easy replacing the transformers for those lights playing up?

I'm very comfortable repairing electronic stuff and doing plugs but have always left light sockets (I dont mean changing the bulb) and wall socks stuff in case I get things wrong. The whole circuit is on the RCD though.

Thanks.

zax47

ey143 wrote: »

Hi

Thanks for the reply and sorry for the delay. Yes, the link you posted, I remember the fittings look like the two holes in the ebay photo. I remember having broken some of the halogens in the past trying to fit them into the socket as it was difficult to fit or remove - probably because of the heat/contraction that you mention. Two questions though:

Is it relatively easy to replace a dimmer switch with a light switch?

Yes, it's fairly straightforward. Is it just that switch controlling the lights, or is there a second one (2-way lighting)? Either way just be sure to take note of what wire is where BEFORE you disconnect the old switch.

If it's the only switch then there will probably just be two wires, if it's 2-way then there will be 3 or even 5;

Loads of good info here to help you;

http://www.ultimatehandyman.co.uk/diy/electrics/light_fitting/index.htm

Is it easy replacing the transformers for those lights playing up?

Yes, just mains in and 12V out. If it's 1 per lamp then the usual rating is 20-60 VA (or Watts) to cover single 20W, 35W or 50W bulbs. Should fit through the hole for the lamp but you'll have to pull the fitting down, not just the bulb. They aren't expensive now;

http://www.discount-electrical.co.uk/section.php/109012/1/aurora-lighting-dias-transformers

I'm very comfortable repairing electronic stuff and doing plugs but have always left light sockets (I dont mean changing the bulb) and wall socks stuff in case I get things wrong. The whole circuit is on the RCD though.

Thanks.

Just read the info in the link. You'll be fine.

TURN OFF THE POWER BEFORE YOU DO ANYTHING AND CHECK IT IS DEAD - THEN CHECK AGAIN!