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What are all of these numbers on the light bulb box?!

Does this scenario sound familiar: I’ve got a light out. I take whatever I have in the basement or the store room and screw it into the socket. Hopefully, the box isn’t too old and the lamp isn’t damaged. But wait, why does it look so funny? This isn’t going to work, and off I run to the store to look for a new bulb. Standing in front of the light bulb shelf I am bewildered; Where do I start?

When replacing a bulb, the most obvious place to start is the shape. There are two sets of letters and numbers on a bulb box that indicate shape. One, calls out the shape of the base (what screws into the socket) and the other calls out the shape of the lamp. The most common base and shape in a household is a medium base, E26 lamp shape A19 whereas in a commercial application, you’re most likely to find a Medium Bipin Linear Fluorescent T8 or T12.

Next, you want to choose the right color for the application. Yes, lamps have different colors. Have you ever been in a Doctor’s office or a school and looked up to see that one lamp in a fixture is yellow and the other looks almost blue? This is not the age of the lamp, but rather the color temperature. They too, went into the store room and grabbed whatever was available. Lamp color is measured in Kelvin temperature. The lower the Kelvin the more yellow, or warmer, as lamp appears. Most homes are lit from 2700K (warm) to 3500K (neutral). Most offices will be 4100K, and warehouses or industrial applications are 5000K or greater; 6500K is daylight white.

Lastly, or maybe initially, you should realize how powerful your light will be. It used to be that wattage indicated how bright a bulb is, and the higher the wattage the brighter the bulb. Wattage is the amount of energy which a bulb draws, but with CFL and LED it is no longer an accurate measure of brightness. Lumen (lm) rating now is used to describe how much light a bulb gives off. This is what should be used to compare brightness of traditional bulbs to their energy efficient counterparts. As a rule of thumb, and LED is about 4 times as efficient as incandescent. So you can divide the Wattage by 4 to determine approximately which LED counterpart will be appropriate.

The next time you need to replace a light, you’ll be better prepared by noting the shape, color suitable, and the wattage which should be appropriate for the space. And if you replace them all at once, it may be the last time you have to change a light, considering LEDs have a much longer lifespan.

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