LED Christmas lights issue?

It is hard to work out from your description what a "supply lead" is or indeed whether these LED light strings comply with UK safety rules.

The whole idea of LED Xmas lights is that the strings are powered by relatively low currents and voltages and as such are intrinsically safe. They usually have a wall wart to provide their power and entirely passive cabling perhaps with an effects controller somewhere along it.

That sounds more than a little worrying. A string of LEDs across the mains is possible (possibly two strings back to back). The first LED to fail and the entire thing stops working. I have seen dodgy Chinese LED lightbulbs like that - some with exposed LED dies at mains potential.

I'd hazard a guess the bulge contained a bridge rectifier and current limiting resistor but it should never have been running hot like that.

If you must continue to use these potential death traps then you are probably going to have to sacrifice one working lead to see what was in there before they self immolated. Blackened mess isn't adequate info.

I think you need to cut open one of the working ones to see what is actually in there. With only the above description there's no way anyone is going to be able to tell you.

According to BigClive.com commercial lights as used for street decorations are 240V so it would be feasible that an LED string would have current limiting resistors in circuit.

Richard

Follow up to the last post

Or current limiting inductors or capacitors

That won't get hot...

According to Big Clive the bulge is a rectifier and designed to be the point of failure. Watch the you-tube video I linked too in a previous post.

Richard

Ive just purchased very similar IP65 rated 240 volt LED lights from Festive UK. They are fully UK safety compliant and consist of six 5m strings of LEDs (which link together) and one power lead with a 13a plug one end, a waterproof two pin socket the other which the first string plugs into and again a square box on the middle where the old ones have the barrel.

Mike

You've not posted the link!

Mike

Second post

The real info we need though is, is there a wall wart as well, or does the bulgy lead contain a mains plug and nothing else? No mention of an effects controller here, which is odd as I thought they all had such things to do strobing, running lights etc. If not and they are all permanently on and are just in series across the mains with a rudimentary voltage dropper of some sort. I'd not touch them with a barge pole. That was basically how the old filament ones worked but you needed to really check for lead, lampholder and their interface damage since all the string would be at mains voltage. There was one naff set of Leeds quite some time ago that were featured on TV since they seemed to use a capacitor so called lossless dropper design, but some of them when they died emitted acrid smoke or burned. You would think that even a cheap brand would have some kind of quality control. Brian

No wall wart, no multi function controller, 13a plug one end, unique 2 pin weatherproof connector the other, barrel containing just two burned out resistors in the middle. Definitely not cheap sold as commercial quality. Replacement 30m string from Premier Ltd £99!

Mike