To replace a fluorescent light ballast, take off the cover of the old ballast, cut out the wiring, unscrew the old ballast and attach the new ballast. Ballast replacement is a common solution to flickering or humming fluorescent lights.
Turn off the circuit that powers the light to ensure safe removal and installation. Take the compartment cover off to reveal the ballast and wiring inside. Clips or nuts may hold the ballast cover in place, or it may just snap in and out. Wire snips or side-cutting pliers work for cutting the old wiring out a few inches away from the ballast.
Removing the mounting nut for the ballast is easiest with a nut driver. Whether the ballast has one or two mounting nuts, it is helpful to hold the ballast in place with the free hand to keep it in place while removing the nuts. Mounting the new ballast into place begins with inserting the nuts into the spaces provided. Strip the electrical wiring back 1/2 inch, and join the wires with matching colors from the power supply to those of the ballast with twist-wire connectors to complete the installation. Turn the power back on to the ballast, and test it with bulbs in place to ensure proper installation.