I've had a certified electrician install 5 outdoor pier column CFL (13W) bulb fixtures with "magic eye" on a fence. With the switch off, at dusk, flickering begins in low wattage for a short period (15-20 min.) then die down, but when I turn-on the power and after 5-10 min. turn it off, the flickering starts at a high intensity and lasts a little longer (20 min.) and then also die down.
I also have 4 other fixtures (18W) installed at the same time (same manufacturer) but on a different switch (circuit) on the entrance piers. These neither flicker at dusk, nor do they flicker after turning them on and off.
I'm concerned about the premature burn-out of these expensive bulbs.
What should I do?

Call your electrician back and ask him to test and recheck his work. He is obligated to provide you with a functioning light.