3 OF 7 LV DOWNLIGHTS MELTED

Had an electrical company fit 7 low voltage downlighters. Two started melting the cable/fitting at the junction between the fitting and the transformer - noticed before it was too late due to burning smell. The boss said it must be faulty transformers. They replaced the two problem ones and checked all the others. 9 months later and the same has happened to a third downlighter. An electrician they sent said one of the wires must have been loose, causing arcing. He replaced the melted one and checked the others again and said no reason to be worried or change the fittings or transformers.

Another (self employed) sparky I mentioned this to said it could be faulty transformers or a loose connection.

Is it safe to leave them now? This is nearly a 50% failure rate, including one failing after they checked them all. Should I insist they change them all? Or change them myself if they refuse?

Any sparkies who've come across failures like this able to advise?

Many thanks

Whats above the downlighters? Are they covered with insulation?

Nasty cheap connector blocks supplied with the fittings where the transformer lead forms a junction with the fitting can melt.

This is because when the terminals are tightened the tube of the connector can split, and if unnoticed will cause a poor connection and melting.

Not uncommon, i would say 80% of my calls for failed downlights are caused by the terminal lego block melting, can be loose connection sometimes a faulty transformer but to be honest the transformers are more likely to shut down before that level of damage is caused at the block if its a faulty transformers , biggest culprit i believe, is that the blocks arent left far enough away from the light and get damaged from heat. Those metal stands theyre attached to (if present) need to be bent away from the light. Sometimes if fitted incorrectly they bend over the light or remain straight up holding the block over the light.

There are hoods above, no insulation. Not sure it is the block hanging over the lamp as only one wire's block had melted. Can't check now as electrician took away the evidence despite being asked to leave it here... Yeeeha!

Think what I'll do is replace the lego blocks, making sure they're tight without splitting them. I'll replace the transformers as well and make sure the stand is keeping the block away from the lamp. That should cover all bases and allow me to sleep at night without wondering when the 4th is about to melt.

Brilliant advice, thanks everyone.