Nonny wrote:

Interesting observation. I know that when a single lead from a neon
light touches a hot wire, the neon light will glow if there is almost
anything touching the other lead. Was used as a voltage checker long
before the IC devices were available. If the neon's lead was touching a
hot wire and the other a ground/neutral, then the lamp glowed brightly,
otherwise, there was a lesser glow.

This leads me to the conclusion that neon lighted switches take
advantage of this ability and do NOT require a lead to ground or neutral
to achieve the low level glow seen in a lighted switch. Perhaps an LED
lighted switch would require a grounded/neutral other lead to work,
together with diode to convert the AC to DC.

If the switch is lighted when off, the neon lamp (and series resistor)
are connected across the switch. The small current through the neon lamp
flows through the load on the switch. For a 3-way switch, the lamp is
connected across the travelers.

For a switch that is lighted (neon) when the switch is on, the switch
probably has a neutral connection. There is a resistor from each side of
the switch to the neon lamp, with the other side the lamp connected to
the neutral.

LEDs could operate essentially the same, probably with an extra diode.

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