In article , Dan_Musicant wrote:
On Sat, 18 Aug 2007 22:56:48 +0100, Derek Geldard
wrote:

:Nowadays domestic users of fluorescent tubes need not concern
:themselves too much, but "Best Practice" is "Best Practice". If you
:have a fitting that requires a lot of effort to get at (above the
:stairs say) it makes sense to get the most out of the tube.
:
G

Yes, DG has it right. The issue is NOT energy usage here but the life of
the bulb. Turning a CF on and off a lot DOES shorten the life. It may
have 10,000 hours MTBF, say, but if you turn it on and off 10,000 times
the life isn't apt to be 10,000 hours! I don't know if the bulbs have
gotten better that way, but what HAS been getting better is the cost of
the bulbs. They still aren't nearly as cheap as incandescents, but the
economy of the situation has incandescents out of the picture. I haven't
bought one in quite a few years.

If I only need a CF on for a few seconds, in my workroom, say, I
generally use a flashlight rather than turn on the overhead light for
10-15 seconds in order to find what I need. At the ceiling are two CF's,
and I don't want to wear them out. I've heard that nowadays the life is
only shortened maybe 5 minutes, but I suspect that's quite inaccurate. I
have had several CF's fail way before they were supposed to. There's a
circular one in my kitchen that would probably cost me over $10 to
place, and the one it replaced lasted maybe 10-15% of the supposed life
expectancy.

My suspicions:

1. Heat - see if it gets unduly warm where that light is. Rated life is
with ambient temperature 25 degrees C (77 degrees F).
Better ones should have only slight incidence of early failures if it
gets a fair amount warmer. But if you have an enclodure around it, try
removing the enclosure.

2. Was it a brand other than GE, Sylvania or Philips? Most "circline"
lamps that I have seen to go into screw sockets have been by Lights of
America so far, and I have had a disproportionate share of LOAs die young.
(However, I have only bought one LOA since 2001 so they may have
improved.) I have also generally experienced LOAs (as well as Maxlites)
to be a little dimmer than others of same claimed light output.

- Don Klipstein )