How to Install a Fluorescent Lighting Fixture

Consider swapping out your old incandescent fixtures for fluorescent lamps. Fluorescent lighting offers consistent, shadow-free illumination, and the best part is that fluorescent bulbs are more energy-efficient than incandescent bulbs. Incandescent bulbs lose a lot of energy as heat, while fluorescent bulbs stay cool and save energy.

How does a fluorescent lamp function? In a fluorescent circuit, starting from the left prong of the plug, the current flows through the ballast, passes through one filament of the lamp, travels through the closed switch in the starter, continues through the other filament, and exits from the right prong of the plug. The current heats the small elements at both ends of the tube, after which the starter opens, allowing current to flow through the lamp.

The ballast is a magnetic coil that regulates the current flowing through the tube. It initially creates a surge of current that arcs through the tube when the starter opens, then ensures the current flows steadily at the correct level once the lamp is lit. In most fluorescent fixtures, the starter functions as an automatic switch. It remains open once the lamp is glowing, and closes when the fixture is turned off.

Many fluorescent fixtures include multiple tubes to provide more lighting. Each tube requires its own starter and ballast. Although it may seem like two tubes share one ballast, in reality, there are two separate ballasts within the same fixture. Similarly, fixtures with four tubes contain four starters and four ballasts. In certain fixtures, the starters are integrated and cannot be replaced individually. Since a fluorescent lamp consists of only three main components, most repairs can be handled by the user. Over time, fluorescent lamps naturally lose brightness, and they may flicker or turn on and off intermittently. These are signs that repairs are needed. A dim lamp generally needs replacing to prevent strain on other parts of the fixture. Likewise, continuous flickering or flashing can damage the starter, causing its insulation to wear out.

Fluorescent fixtures are easy to maintain by replacing faulty parts. If you think a part is defective, simply replace it with a new one. Start by checking the fluorescent tube or bulb. You can install a new one, or if you're unsure whether the tube is burned out, test it in another fixture. To remove the old tube, twist it out of its sockets. To install a new one, insert the prongs into the sockets and twist to lock it securely.

If the issue isn't with the tube, try replacing the starter. Fluorescent starters are rated by wattage, so make sure to choose the correct one for your fixture's tube. To remove the old starter, twist it out of its socket. To install a new starter, insert it into the socket and twist it to lock it into place.

The ballast is also rated by wattage, and like the starter, a replacement ballast must match both the wattage of the tube and the type of fixture. The ballast is the least likely component to fail and is the most challenging to replace, so it should be addressed last when replacing parts. If neither the tube nor the starter is at fault, the ballast is likely the issue. To replace a faulty ballast, first disconnect the power, disassemble the fixture, transfer the wires from the old ballast to the new one—doing so one at a time to avoid incorrect connections—and then reassemble the fixture.

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If the tube, starter, and ballast are functioning correctly but the lamp still isn't lighting, the issue may be with the switch. If the lamp is controlled by a wall switch, replace the switch as explained in the next section. If the lamp uses a push-button switch, simply replace it with another of the same type. Before working on the switch, be sure to deenergize the circuit by removing the fuse or turning off the circuit breaker.

In most cases, the switch is screwed into a threaded mounting nut inside the lamp. The two wires from the switch are usually connected to four wires from the fluorescent tube, often using wirenuts. Disassemble the fixture as needed to access the back of the switch, then install the new switch, transferring the wires from the old switch to the new one, one at a time to ensure proper connection. Reassemble the fixture and restore power to the circuit.

On the following page, we will outline the necessary steps to install a new fluorescent fixture.

Installing a New Fluorescent Fixture

If you're planning to replace a ballast or switch, consider installing a completely new fixture instead. An old fluorescent fixture undergoes similar aging effects as an incandescent one. You can also swap an old incandescent bulb for a newer fluorescent model. Both of these replacements are easy for DIY enthusiasts to handle.

Follow these steps when installing a fluorescent fixture:

Step 4: Mount the fixture against the ceiling and secure it using the screws included with the new lamp. Depending on the style of the fixture, you may need to reassemble it before or after installation. Once it's in place, restore power. Fluorescent lighting is an excellent choice for your home, allowing you to fully benefit from this efficient light source. Publications International, Ltd.