Check your circuit breaker box and confirm that the corresponding breaker is firmly in the "on" position. She holds a Bachelor of Arts from Luther College and a Master of Fine Arts from the University of Idaho, both in stage design and painting. Regardless of whether you're looking to use retrofit or ballast compatible LED tubes in your existing fluorescent fixtures, you'll need to know what kind of ballast your fixture has. Remove one of the working tubes from another fixture and replace it with the suspect tube. Check the light bulb first to see if it has burned out. You can also use a multimeter to determine if the electrodes still hold conductivity. And just to be thorough, you've also checked the main service panel for a tripped breaker or a blown fuse. Step 1. Another possible code in this position is 'FC' which would mean that the bulb is a fluorescent circular bulb. Bulbs are the most common problem with a bad fluorescent fixture. Before removing a broken bulb from a socket, power to the bulb needs to be turned off. Using a digital multimeter to test the bulb; 1. By checking for surface-level issues, cleaning the parts, and looking at the electronics, you can determine whether you have an easy fix or a trip to the hardware store. You can buy 4-lamp electronic ballasts, and you should be paying well over $15 for a ballast unless you're getting the $2-3 new-stock pulls off ebay, which is my preference. References. If the bulb still does not light, the gas may have leaked out and the bulb will need to be replaced. How can I check the starter of a tube light? Check the main power source for the house and see if the circuit breaker has been tripped or a fuse has blown. With a CFL, is there any way to tell if a bulb is bad without plugging it into a socket and trying it out? If darkness forms on one side of the tube, rotate the tube by 180 degrees from how it used to sit. In that case it would be more appropriate to say the bulb has blown. How to Remove a Broken Light Bulb. How To Measure Fluorescent Tubes. When researching your fluorescent bulbs, pay attention to attributes that will help you narrow your options down. Lamp Type. When bulbs age and have been used for a long time, brown spots will appear. Remove the bulb from the fixture if the bulb is still not illuminating. If they appear darkened this indicates the bulb is burned out. For tips on replacing the starter bulb, read on! If there is significant yellowed staining of the plastic at the vent where the two glass tubes enter the base then the bulb has blown. Or in other words, the lifespan of the fluorescent bulb is over. On this site, we will refer to the fluorescent lights as lamps. Checking a common light bulb using a multimeter on the ohm scale. 'FB' or 'FU' indicate that the bulb is 'bent' or 'U-shaped,' depending on the bulb manufacturer. What do you do next? Her theatrical designs, puppet design and construction have been featured in "Theatre Design & Technology" magazine and she has written numerous articles for various websites. If the fluorescent bulb fails to come on, turn the switch off. wikiHow's. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. Check the ends of the tube. If the bulb is the source of the problem, it will not light at all. If you’re armed with a tape measure, here’s a table to show you how to interoperate the length and diameter of your … CFLs come in a number of shapes, the most common being twin tubes, quads, triples, spirals, F type lamps, 2D lamps and circular lamps. By signing up you are agreeing to receive emails according to our privacy policy. Fluorescent tubes are filled with mercury gas and can shatter into very small pieces. wikiHow is where trusted research and expert knowledge come together. Photo 1 shows how to tell if a fluorescent bulb is bad and how to replace it. Install … Look for dark areas at the base of the bulb. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. If there are black rings in the glass nearest the plastic body then the bulb has blown. Include your email address to get a message when this question is answered. Many of us don’t pay attention to our light bulbs until they burn out and when they do, it can be difficult to know exactly which size, shape or style you need to replace the bulb in your fitting exactly. Hunker may earn compensation through affiliate links in this story. Check for power first then the starter (if applicable) and then the bulbs. Simply look at the filament to see if it is broken, or give the bulb a gentle shake to listen for the familiar "tinkle tinkle" of the broken filament in the bulb. How to tell what color a fluorescent light bulb is. 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). We use cookies to make wikiHow great. 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. If you’re still unsure your ballast has bit the dust, then you need to get your hands on a brand new bulb. 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". {"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":"