led Lighting Problem/Fault

[dangie]

Last night my LED landing light bulb turned on even though the wall switch was switched off. It didn’t light at full brightness, but a dull glow. Turning the light switch on resulted in normal brightness. Turning it off it went back to dull glow, not off. After a few minutes the glow subsided and light went off. This happened quite a few times in the next hour, before I decided to remove the bulb.

I’ve Googled it and it appears this can frequently happen with LED bulbs. They can emit a glow even when off. Has anyone else had the same or similar happen? The bulb is quite a few years old, and if I remember correctly it was an inexpensive bulb from Home Bargains.

Bayonet fit 8.6 watt (60 watt equivalent) bulb
Single pole light switch (not a dimmer switch)

 

[TheSmiths82]

It is normal for a lot of cheaper LED bulbs, even with the circuit off there is always a bit of current flowing and this tiny amount of current is enough to make a dim glow. Also the capacitor may still have some charge left in it. I've bought lots of LED bulbs but I tend to buy decent good quality ones from brands like Philips now, they keep their full brightness for much longer, last longer in general and don't suffer from the glow issue even when it is switched off.

 

[dosxuk]

even with the circuit off there is always a bit of current flowing

If it's connected to a normal light switch, then no, there is no current flowing - there's a whacking great air gap in the middle designed specifically to stop current flowing.

If there is actually current flowing, that would indicate a serious electrical fault, such as loose wires arcing.

 

[TheSmiths82]

If it's connected to a normal light switch, then no, there is no current flowing - there's a whacking great air gap in the middle designed specifically to stop current flowing.

If there is actually current flowing, that would indicate a serious electrical fault, such as loose wires arcing.

I believe it is due to electromagnetic induction from near by cables. Although the power to the bulb may be turned off by the switch, the loop in circuit just above is still very much live and is providing power to the next light in the chain. This very small current leak is enough to make some cheaper bulbs glow very dimly. I had an issue with one doing it, it was a very cheap bulb and swapping it for a decent one fixed the issue. The wiring has also been checked, and a new consumer unit has been fitted fairly recently.

There is a lot of videos on YouTube that explains the problem. I am not saying the issue with the original poster is not due to a wiring fault, but it is a known issue with LED lights.

 

[dangie]

Thanks for your replies.
Do LED lamps need a supply & return to work like ‘conventional’ lamps?
My string solar LED lights in the garden are just one long length of wire with LED’s attached to it. There appears to be no circuit?

Note: All of my house room light bulbs are LED. This is the only one which has exhibited this phenomenon. As I said in my original post, it is quite a few years old and was a fairly budget buy from Home Bargains. I’ll replace it with something better once I can find somewhere local.

 

[TheSmiths82]

Thanks for your replies.
Do LED lamps need a supply & return to work like ‘conventional’ lamps?
My string solar LED lights in the garden are just one long length of wire with LED’s attached to it. There appears to be no circuit?

Note: All of my house room light bulbs are LED. This is the only one which has exhibited this phenomenon. As I said in my original post, it is quite a few years old and was a fairly budget buy from Home Bargains. I’ll replace it with something better once I can find somewhere local.

Incidentally the one I had an issue with was from Quality Save, and their supplier was Home Bargains, the importer of that bulb was TJ Morris, the parent company of Home Bargains. The other issue with cheap LED bulbs is they have very poor quality power supplies which means they are not well smoothed. This can cause flicker, even if the human eyes can't detect it. If you're interested check out Big Clive on YouTube, he has made several videos about how modern LED bulbs work, specially in regard to their power supplies.

 

[Snow1964]

Thanks for your replies.
Do LED lamps need a supply & return to work like ‘conventional’ lamps?
My string solar LED lights in the garden are just one long length of wire with LED’s attached to it. There appears to be no circuit?

Yes the need a positive and neutral, but LED bulbs are low voltage, so will be electronics to give correctly supply too. The D stands for diode which only passes current in one direction (but mains supply is alternating current)

Are you sure garden lights are single wire, not twin cables within one outer sheath

 

[dangie]

I tend to buy decent good quality ones from brands like Philips now, they keep their full brightness for much longer, last longer in general and don't suffer from the glow issue even when it is switched off.

I’m off down to Screwfix tomorrow to buy a Philips bulb (or two).

Are you sure garden lights are single wire, not twin cables within one outer sheath

Whoops….. just looked. So long since I put them up. Two very thin wires.

 

[edwin_m]

I've had this flashing with CFL lights too, including one night in a budget hotel when I had to remove the bulb to get any sleep. When several wires follow the same route and one is carrying AC current, it can induce a small voltage in the other conductors. I guess this is enough to light a CFL or LED lamp, or at least to make it flash.

 

[dangie]

Update:
Have fitted a Philips bulb from Screwfix. So far all ok.
After doing quite a bit of Googling, it appears lighting circuits tend to suffer with ‘Ghost or Phantom Voltage’ when the light switch is off. Before I fitted the new bulb I put the multimeter across the lamp terminals. With the switch off there was still 20-22 volts present. I tried it on other lights in the house and the result was the same. For completeness I did the same across the terminals of a bedside lamp which is plugged into a power socket. With the power socket switched off the voltage across the terminals was zero.

 

[dgl]

Note that a power socket might have dual pole switching unlike lighting which generally just breaks the live conductor.

 

[Nym]

If it’s on the upstairs landing and pre 1995 wiring check for faults on other circuits.
Borrowed Neutrals can can issues with voltages floating around.