Flickering Energy Bulb When Switched Off

[keithmdw]

I noticed last night that the energy bulb at the top of the stairs in my house flickers (or rather flashes) every few seconds. Not a bright flash - it was very very faint and didn't light the whole bulb, and unless I had been stood right under it in the dark looking in that general direction I wouldn't have noticed.

Any way, the fitting is one of those triple-headed types where you can put 3 bulbs in - it was in the house when we moved in. However, 3 is a bit too much for the landing, so I have only put 1 bulb in and left the other 2 sockets empty.

I swapped the bulb with another identical one from another room, and couldn't get either to flicker. However, the same (flickering) bulb in another socket on the same triple-headed fitting did flicker.

Interesting though was if I put 2 bulbs into the fitting - the one which has been flickering, and another identical one from another room, then it stops flickering. Remove the second bulb and the flickering returns.

I have now removed the bulb and put a different one in and the flicker is not evident.

Should I be concerned? Have I got something wrong with the fitting or electrics, or is this normal for energy bulbs (I have had energy bulbs for years and never noticed it before though).

I should add that the house is 5 years old (new estate) and we have had no problems with the electrics in the house in the 3 years we have lived there. As the light is on the landing, it is dual switched - one switch upstairs and one down.

 

[JohnD]

not a problem

this is one of the things that can happen with Compact Fluorescent Lamps (Energy-Saving Bulbs) on a lighting circuit with 2-way switching.

There is a very faint induced voltage in the wires, which the CFL stores up until there is enough to flicker.


Sometimes changing the brand of lamp will help.

Much more on
//www.diynot.com/search/forum....t=0&author=&search=Search+Forum&mode=advanced

 

[Adam_151]

Capacitive coupleing, happens on two way switching arrangements, it need not indicate a fault (but some can exgerate the effect; open cpcs, reverse polarity)

Sometimes, depending on how the two way arrangement has been wired, flipping both switches (so the light is still off, but the switches are both in the other position) will make the effect go away and reappear!

Different brands of CFLs will make a difference sometimes, adding another CFL in another lampsocket on the same fixture will either slow down the flashing, or in you case, its managed to make it disappear altogether, adding a filament lamp will make the effect disappear

Basically, the idea that no power can get through when the switch is off is not totally correct, the conductors that are connected to the switch are layed side by side for many metres (particualy in 2 way arrangements), with just the conductor insulation to separate them, this forms a small capacitor, and in AC systems electricity can flow across a capacitor* in a filament lamp this does not matter, a very small current flows through the filament and has no effect, with a CFL it trickle charges teh capacitor in the lamp intil teh voltage is high enough to strike through the gas, which it does (the flicker), its then discharged and it starts over


*Actually, its not flowing across it, but rather charging it one way and then the other, but current is flowing

 

[toasty]

I had this with my utility room light. You can stop the flicker by connecting a mains rated capacitor over the light terminals (i.e connect the capacitor in parallel with the bulb.

I have a bulkhead fitting in the utility room , so just put the capacitor in there connected to the lamp holder connections (with a bit of heatshrink over the bare wire leads)

That stopped the problem for a total cost of some 40p!
A suitable capacitor is this one from Maplin:

http://www.maplin.co.uk/Module.aspx?ModuleNo=98169&C=30869

Another 'solution' is to replace the low energy bulb with a filament bulb

 

[Steve]

Its not a problem. Ours has always done it. Its only a problem if you dont like it.