My bedroom ceiling light ,which is controlled by three wall
switches,is a Philips 100 Watt Low Energy type .The box calls it
"Genie" .It's the kind that has a bulky part just above the bayonet
fitting and looks like four flourescent tubes in "U" shapes .
After I went to bed last night I knocked over a cup of tea and ,using
the wall switch above my bed switched on the light .After cleaning up
the spillage I switched the light off and then saw what I thought was
a lash of lightning but when I looked up I realised it was the ceiling
light flashing .....about once every three seconds or so .I then
switched the light on again but put it off using one of the other wall
switches .Again the light flashed but at a lower intensity. It stopped
after about a half minute or so.

Anyone else experienced this .Do thses lamps hold energy after
switchoff that needs to be dissapated ?. I'm very curious as to why
this happened .

Stuart

"Stuart B" wrote in message
...
My bedroom ceiling light ,which is controlled by three wall
switches,is a Philips 100 Watt Low Energy type .The box calls it
"Genie" .It's the kind that has a bulky part just above the
bayonet
fitting and looks like four flourescent tubes in "U" shapes .
After I went to bed last night I knocked over a cup of tea and
,using
the wall switch above my bed switched on the light .After cleaning
up
the spillage I switched the light off and then saw what I thought
was
a lash of lightning but when I looked up I realised it was the
ceiling
light flashing .....about once every three seconds or so .I then
switched the light on again but put it off using one of the other
wall
switches .Again the light flashed but at a lower intensity. It
stopped
after about a half minute or so.

Anyone else experienced this .Do thses lamps hold energy after
switchoff that needs to be dissapated ?. I'm very curious as to
why
this happened .

Stuart

Its the same process that makes a neon flash with a high enough
value series resistor - the strike voltage is higher than the run
voltage, so as the voltage builds it strikes, runs for a few
milliseconds as the voltage decays then extinguishes, then start all
over again..

Just a guess

Nick

On Sat, 24 Nov 2007 11:35:49 +0000,it is alleged that Stuart B
spake thusly in uk.d-i-y:

My bedroom ceiling light ,which is controlled by three wall
switches,is a Philips 100 Watt Low Energy type .The box calls it
"Genie" .It's the kind that has a bulky part just above the bayonet
fitting and looks like four flourescent tubes in "U" shapes .
After I went to bed last night I knocked over a cup of tea and ,using
the wall switch above my bed switched on the light .After cleaning up
the spillage I switched the light off and then saw what I thought was
a lash of lightning but when I looked up I realised it was the ceiling
light flashing .....about once every three seconds or so .I then
switched the light on again but put it off using one of the other wall
switches .Again the light flashed but at a lower intensity. It stopped
after about a half minute or so.

Nick's answer upthread is mostly correct, but it's not entirely
resistance (although a slightly 'leaky' switch would cause it for
sure), it's most likely cable capacitance. AC can pass through a
capacitor, the 2 (or more) wires in the switch cable act as a low
value capacitor.

The fact it's switched from 3 positions adds greatly to the effect, as
you have more length of parallel cable. This is also supported by the
flash rate being different/intensity being different depending on
which switch is used, as it alters the configuration of live/not-live
wires.

It's interesting that it's a Philips lamp, my better half's flat had
the same issue with one. After much poking around with a meter, I
found that simply switching to a "cheap given away by the electricity
company" CFL solved the issue. Other alternatives are available,
including low wattage normal lamps in parallel, just putting up with
it, etc.



--
The follies which a man regrets most in his life are those
which he didn't commit when he had the opportunity.
- Helen Rowland