A reality based independent journal of observation & analysis, serving the Flathead Valley & Montana since 2006. © James Conner.

12 November 2015

An informal comparison of 60-watt equivalent CFL & LED bulbs

cfl_v_led
Left, CFL. Right, LED.

There’s a seminar on solar energy at Flathead Valley Community College this evening, so its a good day to look at my informal comparison of two energy efficient replacements for the 60-watt incandescent light bulb. The replacements, pictured at left, are a spiral compact fluorescent lamp and a light emitting diode lamp, both with Edison bases. I bought the CFL at Costco for approximately two dollars several years ago, and the LED at Walmart for $2.44 over the weekend.

The bulbs are close to the same size, but the LED bulb is 50 percent heavier. They’re suitable for most, but not all, legacy fixtures. I installed them in a metal shaded gooseneck utility light rated for a 60-watt bulb. I made electrical measurements with a Kill-a-Watt meter, but would have used an oscilloscope had I had one.

Here are the numbers:

cfl_v_led

I lacked equipment to mention three variables: color temperature, spectrum, and lumens. To my eye, the color of the light was warm. I couldn’t discern any difference in brightness or color between bulbs. But a camera might, which is why it’s useful to exam the spectrum with a diffraction grating (a CD or DVD can serve as a poor man’s diffraction grating). LEDs may have closer to a black body spectrum than CFLs. I didn’t have a light meter sensitive enough to measure the difference between 800 and 900 lumens, so I just accepted the nameplate rating, recognizing the number probably is rounded up or down from two significant figures.

Two caveats. I have no idea how reliable these bulbs are. I’ve had good luck with the 13-watt Feit bulbs. They do last for years. The LED bulb is an unknown, but given its price I would not be surprised were it to have a high failure rate. The LED has a long lifetime, but the built-in ballast for it probably isn’t as robust. And, with a sample size of one, I have no idea how much manufacturing variation there is.