How does an illuminated AC light switch work?

Question

I was just wondering how it can work with only the hot wire... Is it using the earth ground? I didn't try wiring it without the ground because I didn't feel like wasting time.

Answer 1

It NEEDS to be grounded. Don't worry about how it's illuminated.

Answer 2

It can't work with just the hot wire.  It completes the path by putting current through the lamp.  However, from your perspective, it appears to involve only the black wire.  If you remove the lamp from the socket, you'll see that the connection to the neutral leg is broken and the switch won't glow.

I know it seems weird, but compared to the neon bulb that lights up the switch, the resistance of the "off" lamp appears quite small in comparison.  So even though the lamp is "off", there are a few microamps going through it, enough to light the little neon lamp.

When you flip the switch "on", the switch closes, and basically shorts out the neon bulb, which is why it goes dark when the switch is on.  

There are some new automotive fuses that work on the same principle and they will light a very small LED lamp when the car's fuse is blown.

Answer 3

a switch should have at least 2 cables going into it. 3 if it's a 2 way switch. If there's only 1 live cable and it's using the earth then that is seriously dangerous. Check and see if the earth is connected to the switch mechanism it should only be connected to the backbox.

Answer 4

Yep

Answer 5

It is internally wired. A wire goes from the hot side, through the switch, through the bulb, and back to ground (or neutral). When the switch is "Off", a differential voltage is created, causing the bulb to light.  When the switch is turned "On", the same voltage is on both sides of the bulb and therefore, will not light.

Answer 6

Magic or VooDoo!