Switch timer does not work with flourescent bulb?

 Is there a problem using a switch timer with a flourescent long-life
bulb? I have had 2 timers do strange things when I replaced an
incandescent bulb with a flourescent. The timer seems to turn on the
light during the day instead of at night. It works fine for a couple
of days, then gets confused with the timer settings.
Thanks
Mark Sabatini

  msabatini2001@yahoo.com wrote:

I've used a bunch of Intermatic timers with fluorescent lighting, including
both CFLs and 4' tubes, without any problems.

I have had flaky results with low-end motion-sensitive wall switches and 4'
tubes, my guess is that the low-end ones are built around resistive
lighting and the motion sensor power source or control is screwed up by the
inductive load of the transformers.  Buying a better "commercial" switch
solved this problem.

 On Mon, 14 Jan 2008 10:08:03 -0800 (PST), msabatini2001@yahoo.com
wrote:


If the timer is digital, it is possible the RF emited by flourescent
is interfering with the timer particularly if they are fairly close
to each other.

 
Such timers ought to have a sticker or notice "incadescent use only"
because they rely on a trickle of current
thru the "off" lamp to run the timer circuit
(rather than using a third wire to supply its own power).

 msabatini2001@yahoo.com wrote:

Yes, the cheaper models say "for incandescent lamps only" or words to
that effect.  I found a more expensive timer that clearly uses a relay
internally and has a battery to power it and I guess the clock circuitry
as well.  The timer I replaced started losing track of time when I
switched to CFLs for my outdoor porch lights.  I think the CFLs put
some high frequency noise on the circuit which confuses a clock chip
that uses the 60Hz line frequency as a reference.  The better model
says it can be used with electric motors as well.

Bill Ranck
Blacksburg, Va.