Lightbulb lady report: Lumens and kelvins
Question: "What are the lumens and color temp of your dimmest G25 bulb? It seems tricky for me to gauge these things just from package labels. For instance, at Freddie's this afternoon I found several bulbs labeled as a 40W replacement - but only 240 lumens. What gives?
Answer: Lightbulb catalogs list 132 to 242 Lumens for 25 watt and 310 to 350 Lumens for 40 watt as standard ranges for the old style bulbs. Old style bulbs use the old fashioned unit of wattage to describe the brightness of light bulbs. Each old-style bulb emits a range of lumens that is dependent on bulb finish, voltage, cathode size and gas inside the bulb.
In contrast to the old bulbs, lumens are used now as the preferred unit of measurement for brightness to help identify LED output for the new generation of lighting. The lumens you see on the package are the lumens for the bulb you are looking at and NOT for all bulbs of the same group.
Old catalogs seldom listed Kelvins of older incandescent bulbs because they are in the same general range. Kelvins came into general use with the rise of the compact fluorescent bulb. The color is generally 2200 to 3200 Kelvin, depending on the bulb finish, cathode thickness, power voltage used, and the gas used inside the bulb. On a dimmer or with a thicker cathode, the color is more yellow. Special gases like Halogen, Xeon, and Krypton inside of bulbs change their Kelvins, so pay attention to these.
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