Why does it take 20-30 seconds for a fluorescent tube to start?

Question

One of the fluorescent lights in my apartment does nothing for long seconds or sometimes even minutes when turned on (then it surprises me when it suddenly comes on). It behaves as if there were some kind of timeout or something before it turns on. Eventually the glow switch comes on and fluorescent tube starts normally then.

I recorded a video about the problem where you can see it takes roughly 20 seconds for the glow switch to come on: https://youtu.be/Bw2DfIFjn8k

What causes this? Is it the problem of the starter or the ballast? The tube seems to be ok.

Answer 1

If you have a starter, that is definately bad. Starters are cheap and easy to install, I can't remember the last time I have seen one. (Electronic ballast don't use starters). Since the lamp appears to be bright the ballast should be good. If there is no starter I would look at the ends of the lamp, the other thing that kills fliorescents is the electrodes have been eaten away inside the tube (the lamp ends are usually very dark when this is the problem) but it looked very bright so go for the starter - they do wear out, I used to keep a box of them handy.

Answer 2

Does the tube have ends that are getting dark? Fluorescent tubes fail by taking more and more voltage to start, until the ballast can't anymore. The difficulty is because the conductive material that should be helping the tube start is now darkening the tube ends.

Obviously if there is a swappable starter, it's the starter.

Otherwise, it's the ballast.