Why shouldn't different types of light bulbs(i.e. incandescent, LED, cfl) be used in the same fixture?

I read this under the CAUTIONS & WARNINGS section of the LED bulb packaging.

...Do not use in multi-bulb enclosed fixtures together with other bulb technologies (e.g. incandescent, halogen, CFL, etc.)...

I have followed this warning, but I would like to understand the reasoning behind it.

  • I assumed that it had to do with the possibility of the bulbs being wired serially rather than in parallel, which could cause an unexpected amount of current to be pulled through the different bulbs. Just a guess though. Sep 16, 2014 at 18:54

2 Answers 2


For a multi-bulb fixture the LED units do not want to be in the area where high heat is generated as would be the case with incandescent or especially with halogen bulbs.

CFLs have their own special considerations if they are used in situations with special types of lamp dimmers. Such special dimmers may not be compatible with LED lighting modules.

Another consideration comes in from the light quality and perception of what the lighted area looks like. LED lamps have a different light character than do other types of bulbs and mixing them together may be perceived as unpleasant in the extreme cases.


For situations involving home automation eg x10 there is a known issue that LEDs won’t work unless at least 1 incandescent bulb is in the fixture. This would be a valid reason to mix LEDs with conventional bulbs. Just my observation.

  • 1
    While this is a valid point, it doesn't address the question of why the instructions say they shouldn't be mixed...
    – FreeMan
    May 8, 2023 at 16:34
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    May 8, 2023 at 16:51

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