Low voltage halogen lights problem

[Adrian]

Hi I seem to have continual problems with some of my LV halogens. I have them all over the flat but a set of eight seeming to be continually blowing. I have replaced the transformers and the lights but five have just blown again, and its usually the transformer that goes. The ceiling void should be large enough as its about a foot. I dont have any problems with any lights on the same circuit just these ones. Is it possible that there is an earth leak, and if so how would I test? The ceiling is plaster board without any access panels so I can only gain access through the light fittings.

Any help or suggestions would be appreciated

Adrian

[Set Square]

What wattage are the lamps? What wattage are the transformers? What type of transformer are they - electronic or wire wound? How many lamps per transformer? What gauge of cable connects the lamps to the transformers? Are any of the lamps very close to joists or other structural members?

It sounds as if the transformer is overloaded. Your answers to the questions above may help to determine whether that is the case. If you have a large number of low wattage lamps connected to a single electronic transformer, you need to down-rate the transformer by quite a lot. Maybe this hasn't been done? [e.g. a 210 watt transformer is fine for 4 x 50 watt lamps - but not for 10 x 20 watt lamps]

[Adrian]

Each halogen bulb is 50watts. Each bulb has its own electronic transformer which is fully dimmable, min load 20w max load 60w. None of the lamps if close to a structural beam. I'm not sure of the guage, standard lighting flex, easily capable of carrying a decent ampage.

[Set Square]

Are you using identical lamp/transformer combinations in other rooms without this level of failure? If so, you need to try to work out what is different about this particular room and its ceiling space. It's unlikely to be an earth problem - the LV side is invariably not earthed.

[Grunff]

Excuse my ignorance, but how does it sound that way? How and why would an overloaded transformer blow bulbs??

[Grunff]

I don't see how an 'earth leak' could possibly be the cause. It sounds very much like that set of bulbs is overheating. Is the void above them insulated?

[Set Square]

Because the OP wrote, and I quote "its usually the transformer that goes"!

It wouldn't - but it's not (usually) the bulbs which are failing.

[John Rumm]

What type of switching do you have? (i.e. conventional switch or dimmer). Is this different from the other rooms?

[Grunff]

Hmm. You make a good argument. D'oh!!

[Adrian]

Conventional switch. In the same room there is another set of lights on dimmers.

[Adrian]

No its a suspended plaster ceiling with a good foot of space. On some of the lights it is definitely the transformer that has gone, on others the bulbs. It could be overheating but in every other room there is the same setup and they all seem to be OK.?

[dave]

Hi I also have a problem of blowing transformers and/or bulbs. I have got as far as seeing that certain brands of electronic transformers can only operate upto a configuration of four when connected to a dimmer. I have yet to install the range of transformers and dimmer that I reckon will do the job so can't give a reccomendation yet. You might want to check with the manufacturer of your transformers that they are suitable for the number of lights you have installed and wattage ( or VA as it seems to be known ) and make sure that the dimmer is the correct type for your transformers. HTH.

[John Rumm]

Had a feeling you were going to say that ;-)

I think you may find the answer in this thread... be warned it does degenerate when small man guarding the bridge makes an appearance! ;-)