How to Change a Magnetic T12 Ballast

Replacing T12 Fluorescent Ballast

• 1

  Disconnect power to the T12 light fixture at the circuit breaker panel, plug or other electric disconnection point. Use the ladder to reach the fixture. Remove the fixture cover, if one is present, and remove the bulbs. Remove the ballast compartment cover. These covers may be held in place by screws, nuts or spring clips, or they may just snap into place.

• 2

  Use the side-cutting pliers to snip the old ballast’s wires a few inches away from the unit. Use the screwdriver or nut driver to undo the screws or nuts holding the old ballast in place, and allow the ballast to drop from the fixture into your hand. Check the old ballast for size, attachment points, voltage and current and note the wiring diagram. Obtain the electronic ballast that matches the old magnetic ballast. Electric supply manufacturers, distributors or retailers can match your old T12 magnetic balance with an exact-replacement electronic ballast.

• 3

  Install the new electronic ballast in the place formerly occupied by the magnetic ballast. If you have bought the correct unit, it should be an exact fit. Mount the new ballast in the fixture with the same type of screws or nuts that held the old ballast. Use the wire stripper to remove about ½ inch of insulation from the ends of the fixture wires and the ballast wires. Use the twist-type wire nuts to connect the matching colored wires together. Replace the ballast compartment cover, bulbs and fixture cover. Reconnect the power.