I have done all these things, and yet I still have my bulb not fire. But it's very inconsistent. It will fire one day, and not the next, or fire a few days in a row then fail. I've tried everything mentioned here so far. I have a 400 Watt electronic Lumatek ballast, plugged into (the first time) a mechanical timer, which worked for a time, then failed, then into an electronic timer, which worked for a time, then failed. I'm starting to think it's the ballast just burning the timers. Where can I find a strong enough timer? both of them were not cheap, and recommended by my local hydroponics store.
Like mentioned here on previous threads, it' cuts off just fine, but it's the firing that is not consistent. The first time around, the mechanical timer had outlets that were timed, and outlets that were not. It was the only thing plugged into the wall directly. My fan, ballast and filter, all went on the timer. Cooling fan and Light/ballast on timer, filter on constant. The filter is always on, and the cooling fan would turn on, but not the bulb. The hydroponics guy thought the blue spectrum bulb I had was conflicting with the ballast, so he swapped it out for a new bulb in the white spectrum. Still not fires....
Any OTHER ideas? I'm kinda just ready to give up. The first batch was a monstrous genetic mess because the lighting was always fluctuating.