LED Lightbulbs: The How and Why
When people think of LEDs, they often think of those tiny blinking lights on computer monitors and the ones inside alarm clocks. LEDs are indeed used for these types of applications, but they are increasingly being utilized for other uses as well. Amidst concerns about the energy consumption of traditional incandescent bulbs, LEDs are championed as a potential replacement for everyday household use. You can get LED bulbs for table lamps, ceiling fixtures, flood lights, and car headlights.
How the LED Works
“LED” stands for “light emitting diode.” It is a semiconductor device that illuminates when an electrical current passes through it. LED bulbs are incredibly efficient. They use less energy to give off as much light as traditional bulbs, and they last much longer (most are rated to last 23 years with three hours of use per day). When they do go out, it is not in one fell swoop, like an incandescent bulb. An LED will gradually give off less light, and the light may change color when it is nearing the end of its life.
LEDs come in colors, including red and green. Many traffic lights, in fact, are made with LED lighting. However, there are no white LEDs. To attain the white light used in homes and offices, manufacturers mix LED colors at different wavelengths, or apply a phosphor material as a filter.
An LED will only cast light in a single direction. On its own, it can’t fill a room with light like a traditional bulb can. For this reason manufacturers engineer reflectors and lenses in LED bulbs and fixtures to distribute light more evenly. The government’s ENERGY STAR program tests LED bulbs for light distribution (among other qualifiers) and awards its seal to brands that closely replicate the lighting experience of a traditional incandescent.
Comparing LEDs to Other Bulbs
One of the main selling points of the LED is its energy efficiency compared to other bulb types. Bulbs are measured in terms of watts and lumens. Watts refer to the amount of energy a bulb consumes, and lumens refer to the amount of light it gives out. An incandescent bulb uses 60 watts to produce 800 lumens. An LED bulb uses only 9 or 10 watts to produce the same amount of lumens.
Compact fluorescent light bulbs (CFLs), characterized by their swirly glass tubes, are another energy-efficient, traditional bulb alternative. They use 14 or 15 watts to produce 800 lumens. However, many people have found them to be an unsatisfactory replacement for incandescents because they give off an unflattering light, sometimes flicker, and can take up to three minutes to become fully lit. In addition, their lifetime shortens when they are turned on and off frequently, or lit for only short periods.
LED bulbs, however, fully illuminate immediately. They do not contain mercury like CFLs do. The quality of light differs across brands. Some household LED bulbs give off a harsh, almost blue or green light, while others are more successful in replicating the warm light of an incandescent. The best way to test LED options without spending a lot of money is to visit a lighting store that has different brands on display.
LEDs are more expensive than other types of bulbs (about $10 is the industry standard for a single, general household bulb). However, they are up to 80 percent more efficient than traditional bulbs, so the upfront cost is offset by utility savings. Replacement costs are reduced as well due to their longevity.
How to Test a Light Ballast
If you’re having problems with a fluorescent light turning on, and you have tried the simple solutions, the problem could originate with a bad ballast. After all, without a working ballast, you can’t have a working light. However, an electrical ballast can be checked quickly and easily with the right tools. Here are the steps you need to take to find out whether this part should be replaced.
Step 1 – Safety
Safety is always paramount when working with electricity, so put on protective eyewear and switch the power off to the lights before you do anything else. Allow the fixture to cool and the stored electrical current to dissipate before you remove the bulb. Put it in a safe place until you’re ready to use it again.
Step 2 – Check the Ballast’s Appearance
Remove the screws holding the protective cover in place and set it aside. Inspect the ballast closely to see if there is any leakage. If you see any indication of such, there’s no need to continue with testing; the ballast will have to be replaced.
Tip: You can continue this testing process after you have a new ballast installed if you feel the need.
Step 3 – Locate the Tombstones and Wiring
Test the high voltage side of the ballast to be sure the electricity flowing between the wires and the tombstones is continuous. The tombstones are the plastic fittings at either end of where the bulbs sit. These contain small metal conductors, and you should see either one or two wires going to each one.
Step 4 – Test the Voltage
Turn the voltmeter to the the ohms reading. Touch the probes a white wire and a colored wire coming from the ballast. The voltage meter should present a reading of a continuous circuit or a short. Any other reading indicates that the ballast needs to be replaced. Test the voltage of the other colored wires on the high voltage side as well, and then test the wires from the transformer. Finally, test the wires from the power side of the ballast.
Step 5 – Check Wire Connections
If all of your readings indicate no electrical problems with the ballast, yet you’re still unable to get the light working, be sure that all of the wire connections to each of the tombstones is secure and that the metal connectors in the tombstones are not corroded.
Step 6 – Reinstall the Bulb
Screw the protective cover back on and refit the bulb in the fixture. Then, you can switch the power to the light back on and test whether your problems have been solved.