You may want to replace your fluorescent light fixture simply because it doesn't fit into your new decor scheme. But if you're doing it because you think it's broken, you may only have to replace the ballast. The basic procedure is the same in both cases. If you don't have to remove the fixture, you can save yourself the trouble of unscrewing it from the ceiling and fixing the ceiling discoloration it will inevitably leave behind.
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Diagnosing a Bad Ballast
The ballast is a magnetic or electronic control box that converts the incoming electricity to a signal that energizes the inert gas inside the fluorescent tubes and makes it glow. It's usually located on one end of the fixture, and it's the point of connection between the fixture and the household circuitry. If it goes bad, you can't service it but you can replace it.
Most ballasts last at least 20 years, but they wear out as humidity and usage take their toll. When a ballast wears out, it sends an inconsistent or weak signal to the bulbs, which can result in one or more of four symptoms, according to Regency Lighting:
- Weak output
- Delayed start
- Dark areas on the ends of the bulbs
In addition, the ballast often starts to buzz when it wears out, and the buzzing continues as long as the power is on.
Disconnecting and Removing the Ballast
When you're doing a fluorescent light fixture repair, whether or not you're removing the entire fixture or just the ballast, you have to disconnect the ballast from power. If it's plugged in, you can simply unplug it, but if it's hardwired, follow this procedure:
- Turn off the breaker controlling the light circuit. Don't rely on just turning off the switch, because someone could turn it back on while you're working and give you a shock.
- Remove the cover from the fixture and remove the bulbs. Handle these carefully because they are fragile. Whatever you do, don't drop them.
- Locate the ballast cover on one end of the fixture, unscrew it and remove it.
- Note the black and white wires coming from the house circuit connected to the power wires on the ballast. Test these with a voltage tester to make sure they're dead, which may require first unscrewing the wire caps, so wear rubber gloves to protect against shock. After verifying the wires are dead, disconnect them.
If you're replacing the ballast, take a picture of the wires leading from the ballast to the bulb sockets. Cut them as close to the ballast as possible using wire snippers. Unscrew the ballast and replace it with one with identical wiring. Use the picture as a reference when splicing the ballast wires to the socket wires with wire caps.
You can leave these wires intact if you're replacing the entire fixture. In that case, locate the screws holding the fixture to the ceiling, unscrew them and take down the fixture.
Ideas for Replacing Fluorescent Lighting Boxes
If you decide to replace the entire fixture, and it's hardwired, you'll see the wires sticking out of an electrical box in the ceiling. The box is usually offset from the center of the ceiling, which isn't ideal for a dome light, but it works well for track lighting. Track lights provide more directional, focused illumination than fluorescent lighting. LED bulbs consume less energy.
If you decide you don't need any lighting at all, don't leave the wires hanging. With the power off, screw a wire cap onto each wire except the bare ground, push the wires into the box and screw on a cover. If you want to patch the hole with drywall, you must disconnect the wires from the circuit and remove them.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker and Family Handyman.