DIYbanter - View Single Post - Switch timer does not work with flourescent bulb?

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wrote:
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.

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.