Manufacturers of CF bulbs warn consumers not to use these bulbs in fixtures with dusk-to-dawn photocells, saying it could shorten their life.
If these photocells are reliable, what’s the problem?
*“Be sure to check the lamp package, which will indicate if the lamp is not intended for use with electronic timers or photocells. Some electronic timers and photocells contain parts that are incompatible with compact fluorescent light bulbs; using these bulbs in incompatible products will result in a shorter light bulb life. To find out if an electronic timer or photocell is compatible with compact fluorescent bulbs, check with the manufacturer of the timer or photocell.”
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From here.
I’d wager that there’s some type of line voltage switching (photocell, motion sensor) that the bulb won’t like.
…As I found here;
*"Motion sensors are not generally used with CF bulbs because the frequent on/off switching will shorten the lamp life, and because in cold weather, outdoor CF bulbs will not provide full light levels until they warm up. Inexpensive magnetic-ballast PL-tube CF bulbs can be used for these on/off outdoor applications but they may need an enclosed fixture to provide enough light in sub-freezing weather. (The lumen output of CF bulbs is quite temperature dependent.)
CF bulbs and photocontrols are an excellent combination if the proper photocontrol is used. You have to use a photocontrol that is rated for use with CF bulbs or inductive loads. A cheap photocontrol is basically a light-controlled dimmer and can cause the same fire hazard as a household dimmer connected to a CF bulb."*
Many thanks for the fine research!