Mains LED lights glowing when off - current induced in cable?

[David Robinson]

I've swapped the GU10 halogens in the centre of our kitchen for LEDs.

Strange thing: the LEDs sometimes glow slightly, even when switched off.

Four different sets of lights are all switched from three locations (2*4-gang 2-way switches, and 1*4-gang intermediate switches), and the brightness of the glow varies depending on what other lights are switched on in the kitchen.

I'm assuming that, because of the length over which all cables are run in parallel, that somehow sufficient current is being induced to illuminate the LEDs, dimly. It probably helps that the cables run along a structural girder for 3 metres.

Do you think this is anything to worry about? I wonder if it's possible to get a dangerous "nip" when changing a bulb? (Not that I'm likely to put my fingers into a bayonet fitting, never mind a GU10).

I know you shouldn't bunch cables together unless suitably de-rated (which these are), but never thought about one cable inducing a current in another cable. Anyone ever take steps to avoid this?

Cheers, David.

[Martin Brown]

The present generation of high brightness white LEDs are just visibly lit when there is a current of around 2uA flowing through them. As long as they are not glowing brightly I wouldn't worry too much.

As they improve the lower current limit keeps on going down. Some are more sensitive than others in any given batch. You can make an LED torch that is always slightly on by bridging the switch with a suitable high value resistor. This is useful in the dark during unexpected powercuts.

[NT]

Cables have capacitance. Its not a problem in any way,

NT

[Mike Tomlinson]

In article , Mark writes

What's the failure mode?

[Mark]

I had 3-4 and all but one just stopped lighting up. The other one would flash on and off.

[Andrew Gabriel]

Unless you spend a lot of money, the LED products you find in the shops are pretty universally crap.

Flashing on and off sounds like PSU failure. The others could be PSU failure, or a single LED or single series chain of multiple LEDs which have gone open circuit.

Stayed in a hotel a few months back which had fitted GU10 leds everywhere. They each had perhaps 15-20 LEDs. The two in the bathroom had about 4 LEDs still working. I swapped them with a couple in the corridor which had about 10 still working, which was the most I could see still working in any of the lamps.

[David Robinson]

The ones in the kitchen (?8? SMD LEDs in each) have a slightly greenish light, and a usually imperceptible flicker which gives rise to strobing when anything moves quickly (e.g. chopping veg).

The one in the hallway (different sort - ALPHA brand - 3 LEDs in it) died after 6 months. Just sat there flickering/flashing wildly. Guess the 25 years predicted electricity savings won't be coming to fruition. Still looking for the receipt to take the thing back. Shame. As a spot light (pointing at a picture), it had a pleasant clean white light and I really liked it. That one was useless for general lighting though.

Cheers, David.

[ARWadsworth]

So you have stopped at the hotel I rewired:-)

Going on my recent work related GU10 LED fittings I guess around 1 in 10 fail within one month (whit around half of those failing within one week).

[Andrew Gabriel]

I'm struggling to remember which hotel stay it was. I can picture the room, but can't recall where it was or why I was there. (That sounds rather sad...) Could even have been Luxemburg or Munich. The more I think about it, it was probably Munich.

[ARWadsworth]

Not Sheffield then:-)?

[Mark]

These were *very* expensive and were bought from a specialist electrical retailer.

[Mark]

IIRC they were Deltech (5W).

I was quite happy with the light output of the bulbs. I had a mix of halogens and LEDs in my kitchen/dining room (9 x 50W). Now all back to halogens :-(