Checking an electronic ballast can provide insight into florescent lighting problems. Testing the ballast will tell you whether it has malfunctioned instead of the lamp or fixture. An electronic ballast is a resistor that limits the amount of electrical current that the florescent lamp may draw. Without a working ballast a florescent lamp will draw too much power resulting in a blown bulb. The ballast resistor consists of a piece of ceramic with two terminals; positive and negative.
Turn off power to the light fixture. Remove the florescent lamp, then unplug the ballast from the side of the fixture.
Switch on the digital multimeter. Change the measurement setting to resistance denoted by the capital Greek letter omega. Capital omega stands for ohms which is the unit of resistance measurement.
Clip the red (positive) lead of the multimeter to the positive terminal of the electronic ballast.
Clip the black (negative) lead of the multimeter to the negative terminal of the electronic ballast. Compare the resistance reading to that written on the ballast itself. If a difference is found or if you get a reading of zero, replace the ballast.
Things you need
- Digital multimeter