What causes a fluorescent light to stop working?

A dead fluorescent can be caused by lack of electrical power (tripped breaker or blown fuse), a dead or dying ballast, a dead starter or a dead bulb(s). Check for power first… then the starter (if applicable) and then the bulbs. When all else fails, the ballast should be replaced.

How can you tell if a fluorescent light bulb is bad?

How to Tell If a Fluorescent Tube Is Bad?

  1. Check the ends of the tube. If they appear darkened this indicates the bulb is burned out.
  2. Rotate the tube in the fixture if the bulb is not darkened on either end.
  3. Remove the bulb from the fixture if the bulb is still not illuminating.





How do you know if a ballast is not working?

If your fluorescent lighting is displaying any of the signs below, it could be a symptom of a bad ballast:

  1. Flickering. …
  2. Buzzing. …
  3. Delayed start. …
  4. Low output. …
  5. Inconsistent lighting levels. …
  6. Switch to an electronic ballast, keep lamp. …
  7. Switch to an electronic ballast, switch to a T8 fluorescent.

How do you tell if your fluorescent fixture needs a new bulb or just a starter?

The older the fluorescent tube is and the older the fluorescent starter is, the less efficient they are at igniting. A tube that takes more than a few seconds to start-up is a clear indicator that the tube and starter may need replacing.

How do you check a ballast?


Quote from Youtube video: Your other test lead to the wires. And see if your meter still reads open line it should read open line open line if you have an analog meter it should not move.

What happens when a ballast goes bad?





The ballast itself can go bad, which causes lights to flicker or even appear to be burnt out, when in fact they aren’t. They require maintenance and energy to power, on top of the power used to light the fluorescent bulb. They are a large part of the equation when using fluorescent lamps.

Is it the ballast or the bulb?

The ballast provides enough voltage to start the fluorescent bulbs, and once they are started, it quickly lowers the current to produce just enough electricity to produce a steady light source. Without the ballast, a fluorescent bulb would attach directly to 120-volt current and quickly burn out the bulb.

How do you test a fluorescent tube starter?

A fluorescent starter can be tested by a multimeter very easily. For this, you need to turn the power off and then attach the multimeter at the one end of the starter. This will show the reading of the electric flow in the starter. If the flow shows normal, then you have a completely working starter.

How do you test a fluorescent light with a multimeter?

Turn the setting on the multimeter to “Ohms.” Touch one probe to the white wire and the other to a colored wire. The meter will display a direct short or continuity. If no reading is displayed, there is a problem with the ballast. Replace it as soon as possible.

How do you check if a ballast is good or bad?



One probe of the multimeter should touch the hot wire connections, while the other touches the neutral wire connections. If the ballast is good, an analog multimeter has a needle that will sweep to the right across the measuring scale. If the ballast is bad, then the needle won’t move.

How do you troubleshoot an electronic ballast?

To measure it, set your digital multimeter to around a thousand ohms resistance setting. Connect the black leads to the white ground wire on your ballast. Afterward, test every other wire with the red lead. When you do this test, a good ballast will return an “open-loop” or max resistance.

How do I test a light fixture with a multimeter?

How to Check a Light Socket With a Voltmeter

  1. Hold either lead on the metal socket casing.
  2. Touch the bulb at the bottom of the socket with the other lead.
  3. Record the reading. If it’s somewhere close to 120 volts, the fixture is good.



How do you check the voltage on a fluorescent light fixture?

Set a multimeter to the ohm (Omega symbol) setting, then touch one tester probe to each of the pins at the end of the bulb. If the tester shows a reading between 0.5 and 1.2 ohms, the bulb has continuity. Repeat the test at the other end of the bulb.

How do you troubleshoot a light fixture?

If the light bulb does not light up at all, follow this troubleshooting procedure:

  1. Check the light bulb first to see if it has burned out. …
  2. Check to see if the bulb is tight in the socket. …
  3. Check the metal socket tab in the bottom center of the socket. …
  4. Check the connections at the switch and make sure that they are tight.

How do you test for a short circuit in a lighting circuit?

The first step in finding a short circuit is to look for physical signs. This may include visible burns or melted metal on wires, burning smells, or flickering lights. Once you’ve identified a potential short, use your multimeter to confirm the voltage by placing it on its resistance or continuity setting.

What are the signs of a short circuit?



There are certain signs that indicate your outlet may be at risk of a short circuit:

  • Outlet has burn marks or burning smell.
  • Buzzing or popping sound coming from outlet.
  • Sparks emitting from outlet.
  • Outlet is over 15-25 years old.


How can you tell if a wire is shorted?

If you suspect a short, look for physical signs of one. This includes burning smells, visible burns or melted metal on wires, hot spots in the wall or cover of an electrical component, sizzling or popping sounds, flickering lights or other signs of inconsistent voltage.