Troubleshooting 8ft Fluorescent Light That is Buzzing

Written by dave donovan
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Troubleshooting 8ft Fluorescent Light That is Buzzing
Eight-foot fluorescent tubes lighting up a subway car. (tube perspective emptiness image by Pali A from

When an eight-foot fluorescent tube fixture is buzzing, the sound it makes can have you thinking you're being invaded by a swarm of bees. What makes things worse is that sometimes, the buzzing goes in and out. The cause of this irritating buzzing can actually stem from a few different problems, including a poor ground, a bad socket, a bad fluorescent tube or a bad ballast, each of which is not that difficult to remedy.

Skill level:

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Things you need

  • Screwdrivers
  • Voltage tester (touch-type)
  • Ladder

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  1. 1

    Turn off the circuit breaker that powers the eight-foot fluorescent light fixture. The buzzing noise should immediately stop when you find the right breaker. Use the touch-type voltage tester to make sure the line is off by pressing and holding the tester's on button and holding the tester's tip up against each of the sockets. If the tester beeps or lights up, then voltage is still travelling through the wires.

    In many cases, you can find the right breaker by reading the chart included in the electrical panel. However, in the majority of cases, the chart is never filled out properly. Therefore, it's important to test the wires before touching any of them.

  2. 2

    Remove the cover lens if the fluorescent fixture has one. Most eight-foot fluorescent fixtures do not have cover lenses, but in the event that yours does, it is the white plastic cover that protects the fluorescent tube.

    The cover may be held in place by an end-cap on each side. Remove the screw that secures the end-cap in place and the cover can slide right out. Be careful to keep a hand on the cover as you're removing the end-cap or the cover can fall and shatter.

  3. 3

    Remove the eight-foot tube by pushing the tube toward one socket or the other. The sockets are spring-loaded, so when you push one side in, the other side will release, allowing the other side of the tube to be pulled out.

    Set the tube somewhere safe as they are extremely brittle and can break very easily.

  4. 4

    Turn the breaker back on. If the buzzing sound doesn't return, then the tube may have been going bad. Try installing a new tube to see if the fixture remains quiet.

    If the buzzing returns without the tube installed, turn the breaker back off and continue to the next step.

  5. 5

    Remove the ballast cover from the light fixture. With the ballast cover removed, you can see the ballast, the wires and all of the connections.

    The ballast cover is located directly behind the tube. It is usually held in place with two screws.

  6. 6

    Test the wires inside with a touch-type voltage tester before you touch any of the wires. Press the button on the tester and touch the tip of it to each wire to make sure the circuit is dead. If the tester beeps or lights up, then the circuit is still live. Try additional breakers until you are sure you have the correct one.

    Check the ballast for any signs of leakage. If the ballast is going bad, it will often be extremely hot and leaking a black, tar-like substance. If this is the case, the ballast is bad and will need to be replaced.

  7. 7

    Tighten the ground screw connection. In most cases, a buzzing fluorescent is due to a loose ground connection. If the ground wire isn't connected to the ground screw, connect it now by loosening the screw, wrapping the ground wire underneath the screw head and tightening the screw down.

    The ground screw is located near the ballast and it will be green in colour. In most cases, it has the word "Ground" imprinted next to it, but not always.

  8. 8

    Check the connections at the sockets to make sure they are tight and secure. If a connection is loose or a socket is broken, replace it. The wires are connected to the sockets via a compression-type clip (usually in the top of the socket). Give the wires a light tug to make sure they are held securely in place.

  9. 9

    Tighten all of the wire connectors and make sure all of the wires and their connections are in good shape and none are corroded. The wire connectors are found where one length of wire is connected with another piece of wire. They resemble little flowerpots and will usually be blue, yellow, orange or red in colour depending on the size of the connector.

  10. 10

    Replace the ballast cover and reinstall the fluorescent tube and lens cover.

  11. 11

    Turn the breaker back on and listen for buzzing. If the problem was a bad ground or a poor connection at a socket, then the problem should be gone. If the problem persists, then the ballast will need to be replaced.

Tips and warnings

  • Always test your tester on a circuit that you know is working before you test the circuit you are going to be working on. This is to ensure the tester is functioning properly.
  • Troubleshooting a circuit often means that you will have to be testing live wires. If you are afraid or unsure of your ability to work with live electricity, please call an electrician to perform this job.
  • Only work on an electric circuit only if you are comfortable in your abilities. If you have any fears, please hire a qualified electrician to perform this job.

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