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I've noticed, that some of the toggle switches (e.g. DC Switch or the four Hydraulic Pumps) have a red Background whereas others (e.g. GEN1 and GEN2) are unpainted. Here you can see what i mean. Is there a special meaning to the red color? First i thought that systems marked with red require a running ENG or APU. But the red on the DOME Light switch obviously does not match.

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  • $\begingroup$ Does the color change between airframes, or are red switches always used for the same switches? $\endgroup$
    – mins
    Oct 13, 2021 at 19:18
  • $\begingroup$ @mins See ymb1's (now deleted) answer. It seems consistent at least since the 200 variant. $\endgroup$
    – Bianfable
    Oct 14, 2021 at 8:28
  • $\begingroup$ @Bianfable: Precisely I have a doubt on the fact they are the same, e.g. on this comparison from two links provided in the answer this is not obvious the same switches are used for A/C fan or windshield anti-ice. In addition on the LH picture A/C fan is bistate and red while on the RH it seems to be tristate and uncolored, which is the contrary of the Hydraulic panel scheme. $\endgroup$
    – mins
    Oct 14, 2021 at 9:36

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There isn't actually any particular meaning to those colours. Those switches have a rubber boot at the base to seal out moisture and outside dust, etc, and the rubber happens to be red because that's what the supplier used. Lever Lock switches like the Gen switches don't have a visible boot (the seal is internal) and a couple of the other ones have no boots or boots that are grey rubber because that happens to be what that particular switch came with.

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    $\begingroup$ I'd really like to upvote this, but my gut says there is always a meaning behind the choices of colors used in control panels. $\endgroup$
    – CGCampbell
    Oct 13, 2021 at 14:07
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    $\begingroup$ I was on the program for 25+ years and I can tell you the colour of the rubber used in the dust boot has no relationship to anything. $\endgroup$
    – John K
    Oct 13, 2021 at 16:46
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    $\begingroup$ They'll just follow the spec for the switch, which might say something like "Boot material of silicone rubber, colour red, to MIL-S-XXXXXXX". As to why red, or black, or grey, if there are any, the reasons are lost to the mists of time... $\endgroup$
    – John K
    Oct 14, 2021 at 11:59
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    $\begingroup$ I've seen switches like these for years in many applications, they're not just in airplanes. Red for whatever reason seems to be the most common color for the rubber. Maybe because it's easier to see if the seal is damaged and needs replacing than with a black seal? Being rubber, they do tend to dry up and crack over time. $\endgroup$
    – Darrel Hoffman
    Oct 14, 2021 at 14:33
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    $\begingroup$ @DarrelHoffman Glass jar rubber seals are red. Rubber bands are (used to be at least) red. The seals on my blender are red. Red just seems to be the most common color for rubber in general. $\endgroup$
    – AndreKR
    Oct 14, 2021 at 15:20

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