Step 3. Sometimes bulbs "unscrew" themselves or become rotated enough for the electricity not to flow correctly over the end pins. All tip submissions are carefully reviewed before being published. By creating an account you agree to the Hunker, The Natural Handyman: Repairing and Troubleshooting Fluorescent Fixtures and Tubes, United Nations Environment Programme: Reducintg RIsk From Mercury. Look at the end of the bulb for a dark area; if you see one, the bulb is either bad or going bad. Hunker may earn compensation through affiliate links in this story. To test fluorescent bulbs, start by checking your electrical panel box to confirm the circuit isn't broken. How to Tell If a Fluorescent Tube Is Bad? Check for power first then the starter (if applicable) and then the bulbs. So, if you see a darker tone on the ends of the bulb or the tube, that means the bulb has been burned off. When working with electronics, make sure the power source is off to avoid electric shock. Knowing the type of fluorescent light you will use with your ballast is a good start to your search. Last Updated: March 29, 2019 References. What we call a "good burn" for a fluorescent lamp, is one that has lived it's normal life, based on published hours of operation, and is that BOTH ends of the lamp are blackened, or grayed with burn rings. You can also use a multimeter to determine if the electrodes still hold conductivity. Note the wattage of the bulb to ensure the correct starter is purchased. If it illuminates, the suspect ballast, starter, or fixture may need to be replaced. Tubes can fall out of a fixture if not properly installed. You must test the fluorescent bulb before considering a replacement. Up next Old starters look no different than new starters, so throw away any starters that have gone bad. Fluorescent light bulbs typically last many years, but when one flickers on and off, or the end turns light gray to black in color, you'll just need replacement light bulbs. And they're supposed to last 22 years or somesuch. Check for power first then the starter (if applicable) and then the bulbs. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. Inspect the bulb and replace it if you see burned or blackened spots. Change out the fluorescent bulb with a new one. When light bulbs shatter as the failure mode then there has probably been a power surge. In some cases, it is possible to "blow" a new bulb/lamp when an older bulb that requires much less energy to fire, does not "blow". When a fluorescent tube burns out, a black spot appears on the inside of the bulb over one of its electrodes near one end of the tube. They’re fragile and have potential to break into shards. 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). Replace it with a fresh one. If that happens, the Environment Protection Agency recommends airing out the location of the breakage, then picking up the pieces with a damp paper cloth. Let’s show you how to tell if a fluorescent bulb is bad. If there are black rings in the glass nearest the plastic body then the bulb has blown. If your fluorescent tubes have recently fizzled out – don’t panic. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/8\/83\/Test-Fluorescent-Bulbs-Step-1.jpg\/v4-460px-Test-Fluorescent-Bulbs-Step-1.jpg","bigUrl":"\/images\/thumb\/8\/83\/Test-Fluorescent-Bulbs-Step-1.jpg\/aid9822564-v4-728px-Test-Fluorescent-Bulbs-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"