I am thinking to replace the regular CFL bulb on a light fixture to a 'Smart Guardian 42-Watt Halogen A-19 Clear 6-Hour Cycle Timer Light Bulb', but because its called 'Halogen', I am little concerned about the heat that it could generate as the light figure has a glass cover dome. Any suggestions on this? I plan to be away from home while this light comes on and I dont want to take any chance. TIA. --Shiva.

  • Did the fixture come with the CFL? Is there a wattage limit listed on the fixture or in the literature?
    – bib
    Jul 5, 2016 at 21:23

1 Answer 1


A 42W bulb is only going to produce 42 Watts of heat (well, a little less since some of the energy escapes as light (roughly 3 - 5% for a halogen)).

So as long as the fixture is rated for at least 42 watts, that bulb will be fine. The max wattage limit should be noted on the fixture somewhere, either on a sticker, or embossed in the metal.

I think your fear of the word "halogen" comes from the number of accidents attributable to 300W and 500W halogen floor lamps with exposed bulbs, these concerns have been mostly addressed with new safety features (primary guards over the bulbs). But a 42W replacement bulb doesn't pose the same hazard.

  • I agree for the most part, a 42w halogen lamp is tiny compared to other 42w lamps, but to a fixture it should be the same. +
    – Ed Beal
    Jul 5, 2016 at 22:35
  • @EdBeal - do you mean tiny in size? The bulb mentioned in the question looks like it's the same as any other A19: homedepot.com/p/…
    – Johnny
    Jul 6, 2016 at 0:25
  • I did mean tiny in size I have some 120v halogens that have a lamp that is at most 3/8" by maybe 3/4" long that are 75 maybe 100w they have a quarts globe that if touched with finger oils they explode because of the heat. Not really had any other lamps do that as bad. But if the fixture says 40/50/60w the 42 w should be just fine as that is the power or heat generated by the bulb.
    – Ed Beal
    Jul 6, 2016 at 1:21
  • @EdBeal - Ahh ok, I think you have something like this candelabra base 75W T4 halogen with an exposed capsule. The A19 lookalikes have a protective glass globe that surrounds the capsule. But as you say, the size of the bulb doesn's matter, just the wattage.
    – Johnny
    Jul 6, 2016 at 2:18

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