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How To Convert T12 to T8 Lighting Ballasts

By Dave Rongey - Summary:

How to Convert a T12 Fluorescent Light Fixture: Wiring a T12 Fluorescent Fixture for a T8 Energy Efficient Ballast, How do I convert T12 light fixtures to T8 electronic ballasts?

Wiring Fluorescent Lighting Fixtures

Electrical Question: How do I convert T12 light fixtures to T8 electronic ballasts?

  • I have about 200 2 ballast T12 lights.
  • I want to start changing them over to T8 single ballast.
  • I would like to know how to wire the lights for the single ballast.

This electrical wiring question came from: Jerry, a Property Manager from Carlinville, Illinois.

Dave’s Reply:
Thanks for your electrical wiring question Jerry.

How to Convert a T12 Fluorescent Light Fixture

fluorescent lighting fixtures

Application: Fluorescent Light Fixture Wiring.
Skill Level: Beginner to Intermediate.
Tools Required: Basic Hand Tools and Safe Ladder.
Estimated Time: Depends on personal experience, the light fixture and access to the light fixture.
Precaution: Identify the light fixture circuit, turn it OFF and Tag it with a Note before working with the wiring.
Notice: Replacement parts for the light fixture should be compatible with the type of fluorescent lamps that have been installed.

Wiring a T12 Fluorescent Fixture for a T8 Energy Efficient Ballast

T12 fluorescent light fixtures have a few different configurations of the actual type and length of lamps, and the number of lamps for each light fixture, so be sure to get the correct T8 Energy Efficient ballast for each light fixture. Refer to the following example which describes the basic conversion process.


  • Each electronic ballast has a complete wiring diagram that describes all of the wiring connections.
  • The wiring is very straight forward and the conversion is very easy.
  • You will be able to use the existing wiring and just replace the old ballast with the new electronic ballast.
  • The lamp sockets work for both T12 and T8 lamps as the pin configuration is the same.
  • Check with your local electric utility company who may have a energy efficiency upgrade program that may offer a rebate that could apply to this project.

Be sure to attach the ground wire to the metal frame of the light fixture.

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Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all projects.

FAQs Frequently Asked Questions and Comments

2 Responses to “How To Convert T12 to T8 Lighting Ballasts”
  1. Bill Zechman says:

    The LED replacement four-foot tube has the familiar bi-pins on each end. Where do I feed the 120 VAC after I eliminate the ballast? Do we apply 120 VAC to each pair of pins on opposite ends? Or do we connect either pin on one end, and either pin on the other end? The LED tube I purchased did not include a wiring diagram, and given the price I paid I don’t want to run the risk of damaging the device.
    Thanks for your help!

    • Dave Rongey says:

      In order to provide accurate information I would need to know more about the exact 4-foot LED lamp that you have purchased, such as the Make and Model Number would be helpful. Many lamps are made to install without and other wiring modifications of the light fixture, but lets make sure we identify which lamp you have first.


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How To Convert T12 to T8 Lighting Ballasts

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