I have two different outdoor floodlights that stay on for awhile and, for some unexplainable reason, turn off. Then, out of the blue, they'll turn back on again. This all happens when it's pitch black outside, so I'm figuring it isn't related to the photosensor. Any idea why this is happening? Could it be mis-wired? Thanks.

Does it happen when the furnace motor is on? Random? Is furnace Carrier?

Some flood and spot lights can detect when they are overheated and they trip themselves to off for a few minutes. Can air freely circulate around these bulbs?

I haven't noticed any relation to the furnace being off or on. I think it happens during the summer, too, when I'm sure the furnace isn't being used. I believe I have Carrier units, though. What have you heard about the Carrier?

I'm thinking the problem might be due more to overheating, mainly because it's so random and it's the same problem on a few outdoor floodlights, which are of the same variety. If that's the case, will a lower wattage bulb possibly take care of the problem?

The AC would be on in the summer, which means the fan. I had problems with an X-10 system and a Carrier which did get solved.

KISS bring in an interesting direction, is there any remote control switch in this system?

Triacs, the solid state switching devices can turn-on by themselves if dv/dt is too high. Harmonics from poorly designed variable frequency drives (ECM motors or Electronically Commutated motors) in HVAC systems. Employing a high cost filter at the HVAC system fixes it.