Mains 'problem' with flashing light globes when switched off.

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Just a quick query, as I imagine somebody here will know what's going
on here:

I have a hallway with two light fittings and two switches at both ends
of the hallway. I had a 4w LED globe in one fitting and none in the
other fitting. Before that, a single CFL globe. Worked fine.

Today I replaced the 4w LED globe with a 2w LED globe. This 2w globe
flashes every few seconds, even though it is turned off at the switch.
If I put another globe in the other empty light fitting, the flashing
stops.

What is exactly going on here and is there any way I can stop it  
(aside from not using this globe or using two of them)?
I have a friend with the same 'problem', only his does it with a CFL.

Cheers

Re: Mains 'problem' with flashing light globes when switched off.


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Looks like your switch allows a small leakage current going to the LED  
lamp, is rectified, slowly charges the capacitor of the LED driver until  
the voltage is high enough to switch on the LED lamp.

As this leakage current is very low, there is only very little current  
available, so the driver's capacitor will immediately discharge,  
switching the LED off very quickly.

This repeats continuously and causes the flashing of the LED.

Putting a load in parallel of the LED (when you put another globe in the  
other empty light fitting) prevents the voltage to build up, because from  
a certain, quite low, level of voltage all the leakage current is going  
through that secondary parallel load.

Maybe some ants took residence inside the switch' enclosure?

If not, maybe replacing the switch will solve the 'problem', or putting a  
quite large resistor parallel to the LED lamp. Think MOhms...

Re: Mains 'problem' with flashing light globes when switched off.


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Many thanks Joe, will keep that in mind, might be easier if I change
to another globe for the time being :)

Re: Mains 'problem' with flashing light globes when switched off.

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it's current flowing through the caqpacitance in the wiring to, and between  
the switches.  

connect a 100nF (or larger) "X2" rated capacitor in parallel with the
lamp sockets.  The best location to install it is somewhere other than
at one of the sockets, as,  if someone installs an old-fashoned bulb
it will get really hot at the lamp socket.

Jaycar electronics  CAT. NO. RG5236




OTOH this instructable used a 12OK resustor

http://www.instructables.com/id/Stop-CFL-lights-from-flashing/

but you'd want ones that are ok with 250V AC, and flameproof  
and jaycar doesn't promise that on their resistors..

--  
umop apisdn



Re: Mains 'problem' with flashing light globes when switched off.


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Thanks Jasen, I'll keep the above in mind but am a bit concerned about
the heat you mention (and potential insurance issues), I might simply
change globes again for the time being.  

I'm assuming that, since it is only some but not all globes that do
this, that some globes are built more cheaply than others and lack the
circuitry to avoid the flashing problem? I've done a bit of a search
just before, and most people point to dimmer or illuminated switches,
which I have neither of. The capacitance you mention makes more sense
in my case.

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