New low energy lights fitted recently, lower power demand etc., good. But my daughter discovered that even when switched off they emit light. Spooky to have glowing lights on the bedroom wall at 3 am. Anyone know the cause and a solution other than reverting to tungsten filament bulbs?
All fluorescents do this, to greater or lesser degrees.
The reason is that fluorescent lamps aren't strictly fluorescent, they're actually phosporescent too. A gas discharge produces an invisble UV light and phosphor powders coated inside the tube turn this into visible light. To get white light, a mixture of phosphors is used. The red-producers are mainly fluorescent (they produce light from higher energy light instantly), the green producers are coincidentally (not deliberately) also phosphorescent -- the light they produce is delayed slightly from when they absorb it.
When you switch off the light you switch off the discharge instantly. You also stop any fluorescent processes and most of the visible light output. However any phosphorescent chemicals in there too will still be storing enerby and releasing it more slowly. They decay over time, but they may be visible to a dark-adapted eye for an hour or two. You'll notice that this residual glow is distinctly greenish too.
a solution to a non problem?
NT
Perhaps he is in his photographic darkroom.
tim
it's been covered hundreds of times before in this and other groups. It is caused by cheap nasty starter circuits in Philips light bulbs. The tube is triggered by tiny currents between neutral and earth which is why it happens when the switch is off. Philips told me this and changed the bulbs I bought for ones that don't do it. They were the 18w variety. It is not a fault with the wiring or anything else, it is the bulbs that should have had a safety recall as they are dangerous in my opinion. Try a different make, don't bother with Philips as faulty bulbs are still being sold.
Exactly, he replied to a question he wanted asking rather than the one that was!
Ron wrote: . Phosphorescence eh? . Reminds me of the time in Cheltenham, myself aged around four, sometime pre WWII, when some bought 'fresh' but apparently about to putrefy, fish sitting on a marble cutting block in the pantry of our house on Hewlett Rd. was observed, in the dark, to be glowing slightly!
Come to think of it that's how those 'light sticks' that you shake to activate, work? No fridges in those days.
BTW the next house we lived in, in Liverpool was 'gas only' and that was in the 1950s!
Off topic I know; but nostalgia!
Try pulling apart the gummed flap of a Jiffy bag in total darkness.
Wasn't the KGB, was it?
Try pulling it apart in broad daylight. Just as difficult.
What about a set of 'glow in the dark' stars and moons on the bedroom walls? Or a night-light?
'Poppycock'
-- Adrian C
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