How to determine which part of the florescent light is at fault.


In my previous post, I showed the way to hook up a simple fluorescent light. That’s good for a new light. What if you have an existing fluorescent light that refuse to light up? It’s very easy to detect the faulty part.

Is the florescent tube blinking or flickering?

If it is, there is a 90% chance that you have a faulty florescent tube. Just twist out the tube and replace it with a new one.

Both ends of the tube are glowing red.

Then the fault is with the starter. The starter acts like a booster to kick start the light. It will weaken over a certain period. Change the starter.

Nothing happens when I switch the light on.

Now this will take some fault finding. If you know how to use a AVO meter, you can remove the light’s cover and locate the ballast. On the two terminals of the ballast, check for continuity with your meter, but I think most household don’t keep this kind of meter at home, as it is an electrician’s tool. So the next best way is to use a test pen.

Using a test pen to determine the state of the ballast is easy, but you have to be careful as it can only be done with the lights switched on. First of all before you do anything, use your test pen to determine if the lights casing can light up the test pen. Make sure you DON’T touch the light with your bare hands. A lot of half past six electricians don’t “earth” the fluorescent lights, so even though there is a leakage, the lights still works but the casing of the lights will be “alive” as well. If the casing is properly earthed, you won’t have to to that because whenever there is a leakage, your Circuit Breaker located at your Main Panel will trip off automatically.

Like I said in the previous post, the live wires should be terminated at the ballast. So at least one terminal of the ballast should light up the test pen. Put you test pen on any one of the terminals to check if electrical supply is present. If there is supply to one terminal, and there is NO supply to the one beside it, then the ballast is faulty. If this is the case, then you switch off the current and replace the ballast. But, if there is no electricity supply to both the terminals, then the reason might be something else.

For the time being, 80% of all faulty florescent lights are due to these 3 faults. The starter, the Tube and the Ballast.

In my following post, I will show how to use the simple test pen to check for the presence of electricity and what to do if all these 3 faults have been taken care of