Fluorescent lighting is one of the most cost effective lighting technologies available. It has been in use for decades and is, once you understand its basic concept, very reliable and easy to trouble shoot. With a fluorescent light, a ballast, or power supply, supplies current to glowing plasma inside the fluorescent tube.
If a fluorescent tube starts to go bad, it will begin to flicker as the plasma has trouble maintaining the reaction that generates the light. Often, the two ends of the tube will ignite, but the centre of the tube will be dark. The tube may buzz or crackle. If your tube is lighting up on the ends, but not in the middle, try replacing the fluorescent tube first. To replace a fluorescent tube, twist the tube with gentle downward pressure until one or both sides drops down from the fixture.
If replacing the tube doesn't do the trick, try replacing the igniter. Sometimes an igniter will not provide adequate power. Igniters are small, round canister looking devices. By rotating the device, two small prongs will be released from the base. Although most modern igniters use plastic canisters, there may still be a number of older igniters in use that use a canister made from aluminium or another metal.
If your light isn't coming on at all, it may be an igniter problem. Try replacing the igniter before replacing the ballast.
The ballast is the main power source for the light fixture. If replacing the igniter and tube don't solve the problem, the fixture's ballast may have failed. Some fixtures, especially less expensive modern fixtures, don't have a ballast that can be replaced. With these fixtures, the entire fixture will need to be replaced. If your fixture has a replaceable ballast, remove the ballast and take it to a lighting supply company for a replacement. The ballast is easy to identify. Although they are a variety of shapes, sizes and colours, follow the wires from the light's A/C power supply to where they enter the lighting fixture. This will be the ballast.