We have a fixture that consists of 4 standard bulb sockets, each socket rated up to 60 Watts - no dimmer. I have no desire to burn 240W while eating, so I switched the bulbs to compact fluorescent (much like we have in the rest of the house).
Now here’s the odd thing. If put in 4 CF bulbs, they will all flicker, enough to drive you mad, but if I replace any one of the 4 with a standard incandescent bulb, the flickering stops. (I’ve rotated the CF bulbs; I’ve swapped out each one individually with an incandescent one and get the same behavior).
Any idea what could be happening here?
For clarity, here is a list of all combos tried:
CF-CF-CF-CF = flicker
I-CF-CF-CF = no flicker
CF-I-CF-CF = no flicker
CF-CF-I-CF = no flicker
CF-CF-CF-I = no flicker
Forgot to mention that I also had swapped out each individual CF (from the original 4) with a fifth bulb to make sure I didn’t have a bum bulb; but I guess I could have had multiple bad CFs, but I didn’t think that likely.
One thing they all have in common is the phase of the power being applied. That’s very likely to be link to the observed flicker.
4 CFs is probably reaching some threshold of mutual effect (e.g. transient current draws from the instant of ionization damping ionization in other CFs in the fixture; enough UV leaking past the phosphor of three neighbors to influence each bulb in close proximity; etc.)
To test this general mechanism, try using only 3 CFs (maybe rotating the empty socket).