How To Replace Ballasts

Light fixtures from the factory are wired with the ballast wires connected directly to the lampholders. When changing a ballast, it is not feasible to disconnect and reconnect the wires from each lampholder. When done this way, the lampholders need to be removed from the fixture. It is simpler and faster to do the following:

Shut off power to the light fixture at the circuit breaker.
Cut the wires close to the old ballast and remove the ballast.
The wires from the new ballast are trimmed of excess length.
The new ballast and lampholder wire ends are stripped.
The new ballast wires are connected to the lampholder wires with wire connectors.

Ballast wire (top) is 18 AWG. Line voltage wire (bottom) is 12 AWG.

Strip wires about 3/8 to ½ inch in length.

Use orange, yellow, or tan wire connector.

Wire connector for ballast to lamp holder connections

Ballast wires are 18 AWG. Use a blue wire connector for up to four 18 AWG wire connections.

Use orange wire connector for more than four 18 AWG wire connections.

Ballast Wire Colors

If a ballast is replaced with the exact same type of ballast, the wire colors usually match.

When a 2 lamp magnetic ballast is replaced with a 2 lamp electronic, or if a 3 lamp electronic ballast is replaced with a 4 lamp electronic ballast, wire colors will not match.

When replacing a ballast where the wires colors don’t match, it is important to understand the ballast wiring concept. Just matching colors could cause a problem.

Wire connector for line voltage wires

Wire connector for ballast to lamp holder connections

How to Replace a Fluorescent Ballast Video

Ballast Wire Nuts

Twist-on wire connectors are also known as wire nuts. Wire-Nut® is a registered trademark of Ideal Industries and is the name of their commonly used twist-on wire connectors. Wire nuts come in different sizes depending on wire gauges and number of wires that are to be connected together. See Wire Connector page for more information.