Fluorescent bulb flicks when switched OFF.

[pike_by_nature]

Hi;

I've got a three-bulb light in my bedroom. It's one of those which is attached to the ceiling; and takes three small 40watt bulbs (bayonet fit). About a year ago, one of them blew, and I replaced it with a fluorescent bulb of equivalent strength. Then a few months agoa second bulb went - again, replaced it with a fluorescent. A couple of weeks ago the third bulb went, and I haven't replaced it yet; but I have noticed that for about half an hour after we switch the light out, one of the blulbs flickers, every 5-10 seconds. Not enough that it comes on; it just looks like a dim flash - one flash each time. A few times I've woken up at three or four in the morning, and noticed it's stopped.

No dimmer switches; nothing fancy. Just two light switches, either of which will turn the light on or off. It seems perfectly normal when it's switched on. The wiring is quite old, and there's no earth wire; but I wasn't blowing bulbs every few weeks or anything, I've no reason to suspect the wiring, other than I can't really imagine what else can be causing this.

Can anyone offer advice?

Thanks;

Tim

[John Rumm]

It is a well known problem. You probably have a reasonably long run of cable to the light that is in close proximity to other live wires. This will lead to a small amount of coupling between them (inductive or capacitive); in effect inducing a voltage in the floating switched live. Every so often a capacitor in the lamp will charge enough to start the bulb conducting and you get a brief pulse of light which discharges it.

The presence of the filament lamp would prevent this since it would simply conduct any charge away. As soon as the last one blew you started seeing the problem.

[Graham.]

This has been discussed here several times. Are they Philips CFLs? Basically they are not too well designed and the capacitance of the live and switch-wire is enough to make them flicker.

[pike_by_nature]

Blow! I searched with google, but obviously not specifically enough. Sorry!

Yes, they are. I bought Philips rather than the el-cheapo option becaus I thought they'd be better designed. That'll learn me!

Do I get the impression I might as well just live with it, then? It's not bothering me, except to make me vaguely worried that I had a loose connection somewhere, for example.

Tim

[meow2222]

If it doesnt bother you its ok as is. If it does, 2 resistors in series picked to dissipate a quarter watt fitted in the base of the fitting would get rid of it.

Philips is one brand I would avoid, the few I've had have been very poor

NT

[pike_by_nature]

Thanks all - I'll fit the new bulb and probably leave it as is.

Tim