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How to
Test a Light Bulb

You've flicked your light switch on and nothing happens - what now? Testing your light bulbs is a useful way to tell whether you're dealing with a problem in your lighting fixture or simply with a burnt-out bulb. Follow this simple guide from Batteries Plus Bulbs to learn how to test a light bulb and how to safely dispose of your used light bulbs.

Tools You May Need

When you're testing a light bulb at home, there are two simple methods - using a fixture that you know works and using a multimeter. While the first method is straightforward in practice, it can be a little more time consuming and may not always be an option if you're using a specific fixture light bulb. In this guide, we'll be examining the second method, which requires the following:

  • The light bulb you want to test.
  • A multimeter: This is a small, portable device that measures voltage, electric current, and resistance. Visit your local Batteries Plus Bulbs to pick up everything you need to test your bulbs.

Keep in mind your project may require different tools. Be sure to always consult the instruction manual to determine if you will need any tools in addition to the ones listed above.

Steps for Testing the Bulb

Now that you're all set with your multimeter, it's time to begin testing your light bulbs.

  1. Set your multimeter: Begin by turning the dial on your multimeter to the "ohms" setting.
  2. Test your multimeter: Touch the two probes of your multimeter together. If this gives you a reading of zero or close to zero, it means your multimeter is working and ready to test your bulbs.
  3. Connect the pins: The multimeter will have two small test probes, which you can touch to the light bulb to get a reading. On a standard incandescent bulb, touch one probe to the button on the bottom, and the other to the side of the casing. If you're testing a fluorescent tube, touch the probes to the pins on the end of the bulb.
  4. Check the reading: The multimeter reading in ohms gives you an indication of whether your light bulb is good or bad. This can vary for halogen and fluorescent bulbs, as we'll see in the next section.

How to Tell if a Light Bulb is Bad

The reading on your multimeter is the easiest way to tell if your light bulb is working well. The multimeter tests the continuity of your circuit, which is necessary for a bulb to function.

  • How to tell if an incandescent bulb is bad: Readings above zero show that your bulb is working, while readings at zero mean the bulb is burned out and it's time for a new one.
  • How to tell if a fluorescent bulb is bad: For fluorescent bulbs, a reading between 0.5 and 1.2 ohms means that your bulb has continuity and should be working well.

While the measurements of a multimeter address the most common problems associated with bulbs, a successful reading doesn't always guarantee that your bulb will work. If your multimeter reading shows a good bulb but it still doesn't function, visit your local Batteries Plus Bulbs location and one of our experts will be happy to take a look.

Light Bulb Disposal

Even the best light bulbs burn out eventually. When it's time to replace your old bulbs, drop by your local Batteries Plus Bulbs to do your shopping and disposal all in one place. We pride ourselves on environmental responsibility, and offer easy battery and light bulb recycling services to help both you and the environment.

If you've tested your bulbs and discovered it's time to purchase replacements, Batteries Plus Bulbs offers a wide selection of options to help you choose the right light bulb. Browse halogens, CFLs, LEDs and more to find the perfect fit for your home or office.