Another CFL Question

 Another question about CFLs:

Everywhere I read that one should use them in lights where they will be
on for at least 15 minutes.  However, assuming one wants to install them
elsewhere, or one happens to want to turn on that light for less than 15
minutes in some instance, is it better to:

1) Leave it on for 15 minutes?  This would be the case if the problem is
that quick cycling of the bulb does not allow the interior to stabilize
and hence stresses it more, or

2) Turn it off when done, even if only a minute later, assuming you're
not returning in less than 15 minutes?  This would be the case if it has
a "quota" of cycles and you've used one up just by turning it on.

(For scenario #1, I guess I'm comparing it to the "memory" problem in
rechargeable batteries.)

--
Evelyn C. Leeper
Nobody believes the official spokesman ... but everybody
trusts an unidentified source.  -Ron Nesen, 1977

 
The "15 minutes" rule of thumb includes startup current, cycle life,
warmup, and maybe a few other things.  Once you pay for the CFL, though,
just use it as you would an incandescent bulb.

One disadvantage (maybe) of some of the new, efficient CFLs is that they
take 5 minutes or so to get to full brightness.  I like that in the
bathroom at night, but you may not want it in the kitchen.  Solution for
multiple-light arrangements (like the floods in my kitchen) is to keep 1
halogen light for "instant-on" purposes, and replace the rest with CFL.

 
  Most CFLs warm up in anywhere from less than a minute to 2-3 minutes.
Ones with outer bulbs tend to start dimmer and take more time to warm up.
Ones with bare tubing tend to be less bad at starting dim, and they take
less time to warm up.

 - Don Klipstein (don@misty.com)

 Evelyn Leeper wrote:

According to the Wikipedia, "In the case of a 5-minute on/off cycle
the lifespan of a CFL can be up to 85% shorter, reducing its lifespan
to the level of an incandescent lamp. The US Energy Star program says
to leave them on at least 15 minutes at a time to mitigate this problem."

But if what you're asking is, "is there a benefit to leaving it on
even if I won't need it again for hours", the answer is no, most of
the wear to the CFL happened at that instant you turned it on, leaving
it running doesn't undo that.

The amount of electricity saved by shutting it off for brief periods
doesn't compensate for the wear and tear caused by turning it on.  The
exact tradeoff point is of course affected by your cost of
electricity, the cost of the CFL, and (information you probably don't
have on) the expected lifetime of the CFL.

Personally, I use incandescents for those short-duty locations like
stairs.

Dave

 On Fri, 20 Feb 2009 10:00:43 -0600, Dave Garland


i have a CFL in the basement that comes on for a minute or two every
day, i've had it since 1991.