In article , Way Back Jack wrote:

Been 20 years since the tubes in the laundry room were replaced, and
these new tubes flicker for about 30 seconds before becoming bright.
Is this just a slow warm-up process due to their supposed
energy-saving features, or did I get a pair of lemons? Thanks.

Are these tubes 1 inch wide 4-footers or 2-footers and replacing ones
hthat were 1.5 inches wide? If so, no wonder they flickered - these take
different ballasts. These 2 different sizes are not electrically
interchangeable.

Are both the new and old tubes 1.5 inch wide 4-footers? If so, are the
new ones energy-saving types said to consume 34 watts instead of 40? If
so, I am not surprised they flickered for a bit. In my experience, 34
watt 4-footers have a higher rate of being cranky than "true 40 watt"
ones, especially in fixtures with "residential grade" ballasts.

- Don Klipstein )