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Having installed a commercial LED ballast and found that the 'off' setting leaves the LEDs glowing faintly, I have heard of a second case of this phenomenon.
The glorious editor (blessed be the ground he walks upon) stayed in a French hotel room that had LED bedside lights, which also continued to glow when 'off'.
Now we are curious. Has anyone else had such an experience?
I have not fully investigated mine yet, but through some quick comparisons would say that my LEDs have around 100µA passing through them, and it may be 50Hz leakage.
Much as I realise there may be as many causes as instances, including me messing up the installation, but does any one know what is going on here?
Bleed through the primary to secondary EMC capacitor maybe? - but where would the return path be?
'Alice'
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I have not fully investigated mine yet, but through some quick comparisons would say that my LEDs have around 100µA passing through them, and it may be 50Hz leakage.
Much as I realise there may be as many causes as instances, including me messing up the installation, but does any one know what is going on here?
Bleed through the primary to secondary EMC capacitor maybe? - but where would the return path be?
'Alice'
Should you feel the need, respond below. No email addresses are collected for marketing purposes from responses to this blog. I will keep it that way for as long as possible.
Comments (5)
I had a similar problem on an LED 'mains' light. The light unit was of the GU11 capsule type fitted with about 20 individual led's. Some but not all are very slightly illuminated when the main switch is off. In my cas, I am pretty sure that it is due to leakeage in the switch wires. We had a flood about 2 years ago and although The switch has been renewed, the glow only started after the flood and more led's seem to glow during very damp weather.
Posted by Tim | January 26, 2011 11:33 AM
Posted on January 26, 2011 11:33
My LED GU10 bulbs provide enough light to safely navigate the kitchen when, ostensibly, off.
I quite like this 'feature' so haven't investigated further so far.
Being 2-pin GU10 my lamps are internally ballasted and EMC filter leakage to Earth can be ruled out as a cause.
For some reason the Neutral is switched to my light fitting. This seems quite dangerous, and I wonder if this is how the electrician was supposed to have done it! But, as the Live is always connected I suspect leakage to the earthed fitting is the culpit in my case.
I may grab a stepladder and a meter this evening and see if I can get some actual data on what is going on in there.
Posted by Jon | January 26, 2011 11:42 AM
Posted on January 26, 2011 11:42
Thanks Tim and Jon.
Well, we all agree it looks like leakage!
My back of an envelope calculation is that 100uA from 240V would take about 1nF
C = 100uA/(250Vx2Pix50Hz)
If this is right (fingers crossed :-), it is much more than just stray capacitance causing the problem.
When I fed mine from a lab PSU (linear), the leds went off completely.
So in my set-up it is almost certainly something to do with the ballast
- which is going back for replace or refund depending on what the supplier finds out about his other units.
I should get a scope on it before it goes back, to see if it is 50Hz.
I am also tempted to try a parallel resistor to bleed 100uA down to a few volts - although these things seem to emit with nearly nothing across them.
'Alice'
Posted by 'Alice' | January 27, 2011 2:56 PM
Posted on January 27, 2011 14:56
It affects CFLs too. I have one in my house which flashes briefly every 30 seconds or so, even when the switch is most definitely off. Some kind of mains leakage, or inductance, being stored then discharged into the circuit.
Posted by Kenny Millar | March 17, 2011 11:48 AM
Posted on March 17, 2011 11:48
Hello, I've experienced this problem also with 20x LED GU10 fittings. All reliably providing enough light when off to walk down the hall way at night. The wiring to the fittings is normal switched live installation and have tried disconnected the earth to the fitting to discount earth leakage. I have purchased some different LED GU10 fittings recently that do not have this 'feature' so i've installed the new ones in the bedrooms and kept the others for the toilet and hallways.
Posted by Graham | March 17, 2011 2:45 PM
Posted on March 17, 2011 14:45