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There are some illuminated switches that operate without a neutral. For a lamp that is lit when the switch is ON, I can envision a circuit diagram that has the switch lamp in series with the switched circuit. But this would create significant additional resistance in the current flowing through the line to the main load. If the switch is parallel to the line, virtually no current should flow since the resistance to the lamp is so much higher than the completed switch circuit.

For switch lamps lit in the OFF position, a switch lamp in series would allow a trickle of current through the actual load, causing a dim glow in a fixture or some current in a motor. This seems wrong.

How do no-neutral illuminated switches work?

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They DO pass current through the switch and light at all times - just a few mA. The indicator is wired in parallel to the switch contacts. For most types of bulbs its not enough for the light to turn on.

However with modern LED light bulbs these types of switches (as well as dimmers, and home automation switches) that dont use the neutral can cause the LED bulb to turn on enough to be noticable or flicker.

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I believe some of these have a neon bulb in parallel with the switch. This means they draw a small amount of current through any light-bulb the switch controls - however this is too small a current to produce any light in the light-bulb.

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A textured polycarbonate moulding designed to allow the glow of the two integral neons to be seen at almost any angle. Easy to install as an addition to existing locations.

  • 250Vac
  • Double neons provide 360 degree visible glow around frontplate
  • Green glow is visible to naked eye
  • One or two-way switch wiring
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From what I've seen, they pass a small current through the switch (and light), and that current is sufficient to power the illuminated switch light.

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I have never looked at a design schematic but do know this. I have seen them fail and on the load side. I had 60 VAC on the load side when off and 120 VAC when on. Removed the switch and the continuity between states show rock solid, 0 ohms off and infinite ohms with a standard Fluke meter. Of course I didn't meg the thing for I don't own an insulator tester or megger, work provides them and for far more important failures. The LED kitchen lights it provided power to was either dim or fully illuminated. I won't deal with a Light Emitting Diode failure at that level, fail on, and just went to Menards and bought a swith without illumantion.

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  • I must correct my continuity statement. Its so obvious that I am wrong but far more embarrased. I should have stated the switch showed infinite ohms off and 0 ohms when on. Please forgive me. My credibility is damaged and once again appologize.
    – Steve Harris
    Commented Jul 5, 2017 at 3:21
  • 1
    'Tis what the edit button is for...
    – ThreePhaseEel
    Commented Jul 5, 2017 at 4:01
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Old thread but just ran into the same thing on a house upgrade. The connected load must be a resistive load. Meaning either it's a light bulb, table lamp plugged into the outlet that's switched, etc.. from the load side of the switch, going to the load itself where it then makes contact with a neutral wire. This completes the circuit a d initiates the glow on the switch with the switch in the OFF position. I had 54 VAC coming to my light with no light bulb inserted into the socket. Illuminated decora was not lit in the OFF position. Screwed in the light bulb and whalah. Switch illuminated. Like the previous person said, it does draw a minor amount of current. To me, this is dangerous and shouldn't be offered to standard applications. The average homeowner changing their light fixtures will be in for a surprise when they think the light switch is off. And yes, people change it without turning the breaker off. This is the first switch I have run into that uses the connected load to operate. And without a connected load, the switch will NOT illuminate. As to be clear, the switch I used isn't a cheap piece of junk. I used a Leviton purchased from Lowes that cost over $10. Personally I think these should be pulled from the shelves until they make a version that adds a neutral for it. And no, sorry to say it does not use the ground that's connected to it to illuminate it. That would be dangerous and cause multiple issues. Yes, neutral and ground are connected at first means of disconnect but the ground is for overcurrent or a lost neutral issue. It is not a normal current carrying conductor.

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  • There are versions with neutral, but the problem is they're not widely sold because light switches so often don't have a neutral
    – Chris H
    Commented Oct 17 at 8:14
  • Do note that the "light" in the switch is either a small halogen discharge bulb (in very old ones) or a led with resistor. The current they use is very small and harmless. How harmless you ask? Remember the voltage tester you father had, the one you touch to a wire and put your thumb on big metal plaque? That's the same kind of halogen bulb in there, yet you don't get shocked or anything. The light in the switch depends on the circuit being complete, it wont light otherwise.
    – Thomas
    Commented Oct 17 at 9:36
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Right off the bat I see that no one can answer your question within the first two or three answers or whatever, and I am here only because I'm looking to see why my illuminating light switch won't illuminate, but the answer to your question is because the switch is grounded. Ground = neutral. If you open up a light switch and do not see a neutral wire then how can you test it to see how many volts are coming through the line? - you use the ground wire as a neutral or if it's in a EMT conduit box then you use the box as the ground or neutral. Of everything I know my own question is still not being answered and that is why won't my illuminating switches illuminate?

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  • Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Commented Jan 31, 2023 at 22:23
  • "Ground = neutral" is flat wrong and potentially deadly. Please read up on that!
    – FreeMan
    Commented Feb 1, 2023 at 12:12
  • This does not really answer the question. If you have a different question, you can ask it by clicking Ask Question. To get notified when this question gets new answers, you can follow this question. Once you have enough reputation, you can also add a bounty to draw more attention to this question. - From Review
    – FreeMan
    Commented Feb 1, 2023 at 12:12

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