How to Test a Lamp Ballast

Fluorescent lights are tubes filled with gas. For the gas inside to glow, an electrical current needs to run through it. A filament running through the bulb glows white hot when the ballast it is attached to sends an electrical current through it. For the ballast to work properly, it needs to provide a consistent level of electrical current. Faulty ballasts may flicker or make a humming noise. Testing the ballast will help you determine whether it is faulty.

Screwdriver
Multimeter

Instructions

- 1
  Turn the bulb in the ballast counterclockwise and slide it out of the ballast. Inspect the bulb for signs of damage and burnt areas. Replace the bulb if it is damaged, and turn on the light to test it.
- 2
  Check the bulb to ensure it is the current for the ballast you are using. Look for the H-number marked on the ballast. Use this number at the electrical supply shop to find the correct bulb for your ballast.
- 3
  Remove the cover at the end of the ballast with a screwdriver. Inspect the ballast for signs of leaking oil. The ballast needs to be replaced if there is an oil leak.
- 4
  Set a multimeter to the continuity function. Touch the probes of the multimeter to each of the wires leading from the inside of the ballast out to the bulb filament. Make sure the wires have a constant continuity by reading the multimeter. Replace the ballast if there isn't a constant voltage.

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