How to Convert a T12 Fluorescent Fixture to a T8

Updated July 20, 2017

Updating light fixtures can save energy and money. Many companies offer upgrading services, but converting fluorescent fixtures containing T12 lamps to T8 is relatively easy once you understand the basics. The ballast and lamps inside the fixture can be upgraded without having to replace the entire fixture. Here we'll walk through the process of converting a T12 fluorescent lighting fixture to a T8 by replacing the ballast and bulbs.

Make sure the power coming into the light fixture is turned off.

Open the lens cover and remove the bulbs. Remove the reflector if your fixture has one, then remove the wire housing.

Use your wire cutters to cut the power and neutral wires coming into the fixture that connect to the ballast. Cap these with wire nuts.

Use your wire cutters to cut the wires connecting from the sockets to the ballast. Now remove your T12 ballast.

Install your electronic T8 ballast inside the fixture. It helps to screw it into the same place as the ballast you just removed.

Using wire nuts, connect the socket wires to the ballast wires by following the diagram provided on the electronic ballast. This will vary with the number of bulbs in the fixture.

Using wire nuts, connect the power and neutral wires running into the fixture to the corresponding power and neutral wires of the ballast.

Replace the wire housing and reflector, and install T8 fluorescent light bulbs. Replace the lens cover.


Make sure wire nuts are fastened correctly by checking that they are tightly secured with no loose wires.


Always turn off the power that runs to the electrical device you are working on to eliminate the risk of shock. Ballasts with polychlorinated biphenyls (PCBs) contain hazardous chemicals and cannot be thrown away in household dustbins, and fluorescent bulbs contain small amounts of mercury. Recycle ballasts and fluorescent bulbs at recycling centres in your area.

Things You'll Need

  • Wire cutters
  • Wire nuts
  • T8 electronic ballast
  • T8 fluorescent light bulbs
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About the Author

Kathleen Michelau is a professional writer who received the President's Scholarship for Journalism in 2002 and holds a Bachelor of Arts in journalism and philosophy from the University of Dayton. She is a Chicagoan who enjoys writing about home repair, hobbies and electronics.