Vintage Consumer Reports: Lightbulb testing

The big round object in the photo at right isn't some early satellite or a giant fitness ball. It's an integrating, or Ulbricht, sphere that we used for an August 1965 report on incandescent lightbulbs to check the quality and quantity of their light output.

Each bulb—we tested five major brands—was suspended in the center of the sphere, whose sides were coated with a specially formulated high-reflectance white paint. A precisely regulated current lit each bulb while a photoelectric cell and meter measured the light output in lumens. We ran the test on the bulbs when they were new and after they had burned for 500 hours.

Our testers chose the 500-hour milestone because most of the tested bulbs had a claimed life span of 750 hours. Some of the bulbs burned out far short of their advertised life, while others well exceeded it. But most lasted just about 750 hours.

Forty-three years later we're still testing lights, though now they're compact fluorescent lightbulbs. We covered CFLs in an October 2007 report and continued to test them for months. Read the results of that testing in this update. Our follow-up tests revealed that some low-priced CFLs aren't lasting as long as manufacturers claim.—Gian Trotta

Essential Information: Watch our video on CFLs, right, and read about Home Depot's new CFL-recycling program.

Comments

[dennis ray]

What happens when you break one?