How to Test Light Bulbs

Light bulbs are a vital part of life, yet most people don’t think about them very much: light bulbs are always there, and they are always on (most of the time) when they are needed. The time comes, however, when light bulbs need require replacement or when new lighting is required.

It is during these times that knowing how to test light bulbs becomes important. The two basic tests for light bulbs are (1) to see if they are appropriate for the area where they are installed and (2) to see if they are operational.

Testing a light bulb for performance

Sometimes a light bulb requires evaluation to see how it compares to a different kind of bulb. This happens a lot when evaluating the effectiveness of compact florescent bulbs compared to incandescent light bulbs. Regardless of what two bulbs are being compared, a few pieces of equipment are required:

  • A Watts up? Pro (or similar) ammeter. This device is needed to measure power consumption of a light.
  • A Konica Minolta CL-200 (or equivalent) chroma meter. This device is used to measure the color temperature of the light, referring to the way colors look in the light. Related to this is a quality of light measurement called the Spectral Power Distribution of a light bulb. This refers to how well the light from the bulb emits the colors of the light spectrum.

With these two pieces of equipment users can compare the quality of light emitted by a light bulb as well as the electric power that is consumed by it. Some people might not need both of these devices because of where their interests lie. For example, an interior decorator is more concerned about the effects of the light on the colors in the room, than about the power consumption of the light bulb. Some homeowners will want to save money on the electric bill more than they care about how colors appear under a certain light fixture. Either way, testing a light bulb for performance is going to require some things that aren’t available in every household.

Testing to see if a light bulb works

How to Test Light BulbsAnyone who has ever come across a large stash of light bulbs knows how valuable the knowledge is of how to test them. The traditional method of testing a light bulb is to unscrew a working light bulb of the same type and screw in the light bulb in question. This approach works at times, but the process has a few problems associated with it:

  • Fingers and hands get burned unscrewing the working light bulb from the fixture. This is a particular problem with incandescent light bulbs that are small heaters that give off light. Serious burns can result from touching a light bulb that has not had ample time to cool off.
  • If one light is all there is in the room, testing a light bulb at night could become problematic due to the impaired vision occurring while the light bulb is removed.
  • Antique light bulbs require special handling: even if they look like a standard bulb, it may require a different voltage than the 120 volts in use now. This means that testing it in a modern fixture could burn it out, lowering its value.
  • Testing light bulbs becomes difficult if they don’t fit any available operational fixtures. Taping wires to a light bulb to try to test is a dangerous thing to do.
  • The required voltage of a light bulb is not known in some cases.
  • The time it takes to screw in and remove a large number of bulbs makes the process impractical.

The best way to test a light bulb without putting it in a socket and attempting to turn it on is with a multimeter. A lot of people who like to work around the house have a multimeter already. If necessary, these devices are found in the electrical section of home improvement shops or other stores like Radio Shack. Once the meter is available, the test is very simple and is performed in just a few steps as follows:

  1. Connect the test probes to the multimeter.
  2. Rotate the switch to select the Ω setting of the meter. If more than one option is available, select the lowest number.
  3. Test the meter by touching the two probes together. This should give a readout of 0.
  4. Hold one probe to the side of the light bulb’s base and hold the other to the contact on the bottom. The test probes must touch the two contacts on the light bulb without touching each other to avoid an erroneous reading.
  5. Check the display. If the multimeter display shows very low, then the light bulb filament is intact and the bulb works. If the meter doesn’t change, the filament is open and the light bulb is bad.

Light bulbs affect lives more than most people realize. For some, the quality of the light bulb might strain eyes or make graphics designers make mistakes in color selections. Others may have a higher electricity bill because of failure to test the performance of alternative light bulbs. Then there’s the far more basic need to test whether a light bulb is operational or not. A familiarity with these ways of testing light bulbs will help consumers get the most from their light bulbs.

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