230v ac to 12v ac halogen transformers melted

[Thys LOW Elektries]

Good day, a client phoned me about 15 or so downlights not working on his premises.
On inspection, I found that the downlights were 12v ac halogen bulbs. The transformers were in a floor/ceiling cavity with green isolation material. Most of the transformers were melted in the exact same spot, the coil output side of the transformer.
My question now is it wise to install these transformers with the halogen globes in a non-ventilated area? Or could there maybe be another reason why the transformers melted, other than heat?





I find this rather interesting. Oh yeah, I forgot to mention that the installation is more than ten years old!

[Dylboy]

Very interesting! My first thought is a surge, second to that is just component failure over time.

I personally would push for a full change to GU10, then it's easier to change bulbs and much more energy efficient.

I have taken quite a number of those out for GU10 as well as those big transformers that did a number of downlights

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[GCE]

There is a section in SANS10142-1 on LV Lighting

I would be more nervous on the heat from the lamps especially if you saying it is a ceiling /floor void .

They guys installing insulation material are meant to leave the areas around transformers and lamps open so as to avoid heat build up.It is possible that the insulation went in afterwards and was never done correctly

As Dylboy stated - Get the client to change to GU10 LED lamps which will more than likely be cheaper than changing all the transformers

[Thys LOW Elektries]

Busy upgrading 15 plus lights to gui10 led's, also there is a bunch of 12v lights that look like bananas popping out of the ceiling.
I will be changing them to adjustable gui10 fittings, a lot of time will go into very little work

[Andrew_van_Zyl]

I insist on changing to LED. The heat from these things is incredible, nevermind the power consumption. I've tested halogens to 70W. Times this by 5 or 6 in a kitchen...

[Isetech]

A note, dimmers feeding old downlights are generally not compatible with new LED lamps.

[Thys LOW Elektries]

Thanks for that bid of advice. Will have to upgrade dimmers also, had not thought about that

[Dylboy]

Also didn't know but makes sense, had a client DIY change to LED GU10 but used the same dimmers and it was flickering, I just said it's the dimmer used so lucky guess but good to know for fact now

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[Derlyn]

Thanks for that bid of advice. Will have to upgrade dimmers also, had not thought about that

Or just leave one halogen in the circuit. The dimmer then sees that halogen and works perfectly.

Whenever I have a problem with a dimmer and LED lamps, I just replace one of the lamps with a halogen and problem solved.

[Isetech]

Leading and lagging/trailing edge, do some research and it will help you understand why you need to replace the dimmer.

[AndyD]

..........The transformers were in a floor/ceiling cavity with green isolation material......

I think that's the answer to the problem right there. ELV lighting transformers and electronic power supplies are designed to work in free air with natural ventilation, if they were laying on roof insulation it would cause them to run much hotter than normal. Any components in the roof space should be mounted above the insulation on a baton or truss.

[Isetech]

In reality, not going to happen, the lamp holder attached to the transformer is too short

I think that's the answer to the problem right there. ELV lighting transformers and electronic power supplies are designed to work in free air with natural ventilation, if they were laying on roof insulation it would cause them to run much hotter than normal. Any components in the roof space should be mounted above the insulation on a baton or truss.

[Tang]

Hi, back in 2002 we had to mount wire wound transformers on fireproof surface and not in contact with roof insulation.

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[Isetech]

Yip, SANS 10142-1:2003 edition 1.1 (amended 2003) page 248 7.8.7 Heat generation ............... shall be suitably guarded and installed and located well away from combustible material to prevent contact.""

I do recall this, because at the time we were experience a number of challenges with low voltage lighting, especially when the 50 Watt halogen light was being connected to those huge 230/12 transformers and people were using speaker wire to connect 6 of them together.

I had a customers with 90 x 50 watt lamps = 4500 watts ... eeeeish, they could leave the lights on in winter and keep the house warm.

Hi, back in 2002 we had to mount wire wound transformers on fireproof surface and not in contact with roof insulation.

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