Bulbs with black ends can run for a long time and they won't damage your ballast at all. But you should have replacement bulbs on hand for the day when they begin flickering, take a long time to fire up or finally give up completely. That's because running a fluorescent fixture with a burned-out bulb will damage the ballast.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.
- Replacement bulbs