I have a few light fixtures around the house where there are multiple sockets per fixture - 4 sockets/fixture in the kitchen, dining room, bathroom ceiling light fixtures. I began the process of converting these over to using all CFL bulbs, but wanted to use up the supply of incandescent (Edison) bulbs I previously had. Thus, in some fixtures, there were 2 CFLs and 2 Edison bulbs.

I have noticed that when bulbs have failed in those fixtures, it was usually the Edison bulbs. Is there a particular reason(s) why having CFLs and Edison bulbs in the same fixture might be bad?

Assume that each bulb is rated for the same actual wattage.


1 Answer 1


2000 hour typical life for "Edison" (incandescent) bulbs, 12,000 typical for CFLs, yes, the incandescent bulbs are going to be most likely to fail first...

The only bad thing about using both kinds in one fixture is that it will make things warmer for the CFLs, which may hurt their life slightly. The fixture as a whole will run somewhat cooler, as the CFLs throw less heat than equivalent incandescents.

  • \$\begingroup\$ I should have clarified in my original post: It seemed like the Edison bulbs in the "mixed bulb" fixtures did not last for their rated minimum hours... In other light fixtures in other rooms that were only Edison bulbs and roughly used for the same amount of time each day, those bulbs lasted longer... It seems as if having the "mixed bulb" fixture shortened the life of the Edison bulbs... \$\endgroup\$ Commented May 29, 2014 at 1:48
  • \$\begingroup\$ I suppose it could be remotely possible that in close proximity the switching frequency (25 kHz or so typically) of the CFLs might have some effect on the incandescents, but that's pure speculation. \$\endgroup\$
    – Ecnerwal
    Commented May 29, 2014 at 2:38
  • \$\begingroup\$ I've actually had a similar experience, but don't know the root cause. Then I started using LED bulbs and I love them. Never going back. Less wattage(and therefore heat), just as bright if not brighter, no "slow turn on" like CFLs. The only down side is they need special dimmers if you want to have them dimmable. \$\endgroup\$
    – Daniel B.
    Commented May 29, 2014 at 4:22
  • \$\begingroup\$ My personal opinion, based on what I've seen so far, is that LEDs are best done by getting a purpose-built-from-the-ground-up LED fixture that does not have to work around the compromises inherent in the "incandescent-light-bulb-replacement" shape, so it can most efficiently point the light one direction and the heat another. I (also) greatly prefer them to CFLs... \$\endgroup\$
    – Ecnerwal
    Commented May 29, 2014 at 17:58

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