How to test a fluorescent light bulb with a multimeter
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Fluorescent lights are one of the cheapest ways to light up a home. They use electricity and gas to produce light. When it comes to conventional lamps, these lamps use heat to generate light, which can be expensive.
A fluorescent lamp can fail due to a lack of current, a faulty starter, a broken ballast, or a burnt out light bulb. If you are dealing with a faulty starter or no current, you can fix these issues without too much trouble. But to deal with a broken ballast or a burned out light bulb, you will need to follow a few test steps.
Below is a complete guide on how to test a fluorescent light bulb with a multimeter.
In general, to test a fluorescent lamp, set your multimeter to resistance mode. Then place the black wire on the pin of the fluorescent lamp. Finally, place the red wire on the other pin and check the resistance value.
We will discuss these steps in more detail below.
How to identify a burned out fluorescent lamp?
If the fluorescent lamp is burnt out, its end will be darker. A burned out fluorescent lamp cannot generate any light. Thus, you may have to replace it with a new fluorescent lamp.
What is a ballast in a fluorescent lamp?
The ballast is a vital component of a fluorescent lamp. It simply helps to regulate the electricity inside the light bulb. For example, if a fluorescent lamp does not have a ballast, the lamp will quickly overheat due to uncontrolled electricity. Here are some common signs of bad ballasts. (1)
- flickering light
- low output
- chewing sound
- Unusual delayed start
- Fading color and changing light
What to do before testing
Before jumping into the testing process, there are a few more things you can try. Proper inspection of these can save a lot of time. In some cases, you do not need to test with a multimeter. So, do the following before testing.
Step 1. Check the condition of the circuit breaker.
Your fluorescent lamp may be malfunctioning due to a tripped circuit breaker. Be sure to properly check the circuit breaker.
Step 2: Check for Dark Edges
Secondly, take out the fluorescent lamp and check the two edges. If you can detect any dark edges, this is a sign of reduced lamp life. Unlike other lamps, fluorescent lamps hold the filament to one side of the lamp fixture. (2)
Thus, the side on which the thread is located depreciates faster than the other side. This may cause dark spots on the thread side.
Step 3 - Inspect the connecting pins
Typically, a fluorescent light fixture has two connecting pins on each side. This means that there are four connecting pins in total. If any of these connecting pins are bent or broken, current may not pass through the fluorescent lamp properly. Therefore, it is always best to carefully inspect them to detect any damage.
In addition, with bent connecting pins, it will be difficult for you to fix the lamp again. So, use pliers to straighten out any bent connecting pins.
Step 4 – Test the light bulb with another bulb
The problem may not be the bulbs. It could be fluorescent lamps. It is always a good idea to test a failed fluorescent lamp with another lamp. If the bulb works, the problem is with the bulb. So, replace the fluorescent lamps.
Step 5 - Clean the Holder Properly
Rust can form quickly due to moisture. It can be connecting pins or a holder, rust can significantly disrupt the flow of electricity. Therefore, be sure to clean the holder and connecting pins. Use a cleaning wire to remove rust. Or rotate the light bulb while it is inside the holder. With these methods, rust deposits in the holder can be easily destroyed.
4 steps to test a fluorescent lamp
If, after following the above five steps, the fluorescent lamp is still not producing positive results, it may be time for testing.
Step 1 Set the DMM to resistance mode.
To put the DMM in resistance mode, turn the dial on the DMM to the Ω symbol. With some multimeters, you will need to set the range to the highest level. Some multimeters do this automatically. Then connect the black lead to the COM port and the red lead to the V/Ω port.
Now test the multimeter by connecting the other two ends of the probes together. The reading should be 0.5 ohms or more. If you do not get readings in this range, it means that the multimeter is not working properly.
Step 2 - Check the fluorescent lamp
After setting the multimeter correctly, place the black probe on one lamp post and the red probe on the other.
Step 3 - Write down the reading
Then write down the multimeter readings. The reading should be above 0.5 ohms (could be 2 ohms).
If you are getting an OL reading on the multimeter, it means the bulb is operating as an open circuit and has a burnt filament.
Step 4 - Confirm the above results with a voltage test
With a simple voltage test, you can confirm the results obtained from a resistance test. First, set the multimeter to voltage mode by turning the dial to the variable voltage (V~) symbol.
Then connect the terminals of the fluorescent lamp to the fluorescent lamp with wires. Now connect the two leads of the multimeter to the flexible wires. Then write down the voltage. If the fluorescent lamp is good, the multimeter will show you a voltage similar to the voltage of the lamp transformer. If the multimeter does not give any readings, this means that the light bulb is not working.
Keep in mind: During the fourth step, the main power must be turned on.
Summing up
You don't need to be an electrical expert to test a fluorescent lamp. You can get the job done with a multimeter and some wires. You now have the necessary knowledge to turn this into a DIY project. Go ahead and try the fluorescent lamp testing process at home.
Take a look at some of our articles below.
- How to check Christmas garlands with a multimeter
- How to test a circuit breaker with a multimeter
- How to use a multimeter to check the voltage of live wires
Recommendations
(1) regulate electricity - https://uk.practicallaw.thomsonreuters.com/8-525-5799?transitionType=Default&contextData=(sc.Default)
(2) life span - https://www.britannica.com/science/life-span
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