How to Replace a Ballast Transformer

A ballast transformer is usually found in older fixtures. They tend to be magnetic and they are the single most important component that is responsible for the 'light' that is produced in your fluorescent tube. When you open the fluorescent fixture and pull out the tubing, you will see the transformer. It is usually pretty large and clunky looking. Cheap transformers or transformers that no longer work will make noise. The fixture will hum or buzz. At that point, you know that you will need to replace the ballast transformer.

Step 1 - Take Down the Lamp

Turn off the light and turn off the circuit, for extra safety precautions. Pull down the fluorescent tube and lay it down on the table. Lightly clean the exterior with a dusting rag.

Step 2 - Open and Remove Transformers

Open up the fluorescent tubing and remove the ballast transformer. Some fluorescent lighting will have 1 transformer and others will have 2.  If your light has 2 transformers, they will be at opposite ends of the tubing, connected by either 2 or 4 wires each. Using a wire cutter, remove the 2 old transformers.

Step 3 - Purchase the Right Ballast Transformer

Once you have the transformers removed from the fluorescent light, make a note of the type, size and voltage of the transformer. Take a trip to an electrical supply store and purchase a new ballast transformer. You need to purchase a replacement that is the same type and has the same ratings as the old transformer, otherwise it either will not work with your fixture or it will cause even more damage.

Step 4 - Pull out the Manufacturer's Directions

Each ballast transformer will come with a set of manufacturer directions. Take out the directions and read through it thoroughly. The directions will walk you through how to put the new ballast transformer into place.

Step 5 - Reassemble Fluorescent Tubing

Reassemble the tubing. Crimp any wires and secure all of the connections. You can test that you have done this correctly by using a volt meter. Test the voltage between the connections.

Step 6 - Put Lamp Back in Place

Put the fluorescent lamp back into the lighting fixture. Turn the circuit back onto the on position and test the light by turning on the switch. It may take a couple seconds for the light to warm up and to produce a nice bright light. Your ballast transformer should la