Back in the early 1990s, when a power disruption would occur (lightning switched the photocell off for a moment) or power went out, It would obviously take about 5 minutes for the mercury lamps in my neighborhood to come back on.  However, some of them, when coming back on, would flicker (flash) repeatedly before coming on to a solid state and warming up.  I don't see this in Mercs today.  Is there a reason for this?

The town I currently live in is still predominantly lit with 400w mercury GE cobraheads from the 60's and 70's. The fixtures with the oldest lamps ive noticed do this too, some will flicker violently for nearly a whole minute before stabilizing. Im not sure what causes this either, but it only seems to occur on the hot restrike. I wish I knew somebody who worked for the department of public works here (municipal service techs) as theres a cobrahead with a missing drop lens that has a BT shaped yellow coated mercury lamp in it that I just noticed when doing a job on the outskirts of town. I will have to drive by some night and see it operating. Sadly one by one, the town is slowly replacing all these old 400w cobraheads with LED ones. Ide love to get my hands on some of the removed fixtures and lamps, as many are very old.

My 175W Philips Lifeguard does it. It was NOS installed 2 years ago.