Charm and Practicality of Illuminated Switches

Having had my home rewired, we took that opportunity to add swiches and receptacles in creative ways. With our abundance of electronic equipment, it quickly became evident that we made the right choices. Dual Gang “Receptacles” in several places (4 outlets total per location), Dual Gang “Switches” in several places, and 2 Dual Gang Switches with each having a Switch and Receptacle in one Gang (unswitched Receptacle, but the option to use the switch to control the receptacle is there), so the switch in that gang position moves left and right, not up and down. And one of those switch/receptacle combinations has a Three Way Switch, that was not a stock item in local building centers, I bought it on Amazon, it’s made by Hubbel or Levington, so it’s quality.

Things have improved since my last whole house rewire (different home of course). The GFCI (Ground Fault Current Interrupting) Receptacles are now self testing, they still have a test button, but they run their own internal test every X number of seconds and open (turn off) if they fail the test.

We have one Switch/Receptacle Combo (one mentioned above) that includes a pilot light on the switch, a little LED. We use that switch for the outdoor light, a rear deck motion sensing LED flood, with the switch located in the kitchen. But the LED pilot light, red when the switch is on, unlit when off, serves as an interesting start point for Lighted or Illuminated Switches.

rear-deck-kitchen-mounted-switch

 

Rear Deck Light Switch, and GFCI Protected
Receptacles and Switch Receptacle

I read an electrical forum entry about lighted switches. The interest varied among contributors, but one finally said it’s not worth running the extra neutral for them. Aha, clearly this individual doesn’t understand how lighted switches work. This person was, in fact, correct about the LED Pilot Light (see above), it needs a neutral (unlike a “lighted switch” the pilot light is on when the switch is on), but in my situation, being part of a Switch/Receptacle combination, it has a neutral. The classic lighted switch uses a neon bulb to light the inside of the moveable part of the switch, the thingy labeled on/off on most switches.

There’s a little understanding of electricity needed to understand how neon illuminated lighted switches work. Basically, when the light switch is closed, or “on”, the current flows through the wires, from Hot to Neutral, lighting the bulb. With the switch “open” or off, this current loop is broken, and no current flows, so the bulb is unlit.

 

If I put a high input impedance (high resistance) volt meter across the open light switch, and the light bulb it controls is in the circuit, the current will flow from Hot, through the meter, continuing through the circuit through the light bulb (but not lighting it, the current is reduced by the high impedance of the meter), and back to Neutral, and the meter will show the full line voltage. If the bulb had similar resistance to the meter, the meter would show half the voltage and the bulb would experience the other half. If the switch is open, with the meter across the switch, and reading the voltage across the switch, and the bulb burns out or is removed, the reading on the meter will go away because there is no complete path back to the source.

switch-closed-bulb-removed

E=IxR is the mathematical expression for Voltage equals Current Times Resistance. Since everything is in series, the current is the same throughout the circuit. The open switch represents infinite resistance, so by simple math, the source voltage will all appear across the open switch, but actually measuring the voltage will slightly to severely alter the circuit. Instead of the infinite resistance of the open switch, the impedance of the meter is used in the calculation. That’s why meters with very high input impedance (resistance) are generally invaluable, when measuring voltage, because they don’t change, or minimally change, the operation of the circuit. See comments on this at the end of the article.

The neon bulb takes the place of the meter. So, if the switch is open, and the bulb is intact and in the circuit, the neon bulb in the switch illuminates. Mind you, it doesn’t need to be a bulb in the circuit to make the lighted switch work, we have two lighted switches that control lighted ceiling fans, so as long as the light on the ceiling fan is switched on and at least one bulb in place and not burned out, or the ceiling fan is switched on, or both, the lighted switch will light when the wall switch is open, in other words only lights when the fan, lights, or both, are not being actively powered by the wall switch but are in the circuit.

switch-open-neon-bulb-1

So, by looking at the switch, I can tell if power exists in the circuit, that a light, even a remote light, is available to turn on (bulb in circuit, filament in bulb intact). By using a lighted switch, upon entering a dark room, I can immediately see where the switch is, this can be invaluable in preventing falls, as you get older, balance is an issue, and in dark rooms, people can start to fall over without realizing it. Even the presence of a lighted switch can help to keep balance in the dark as it’s a reference point. On one ceiling fan used extensively in hotter weather, I can tell if the switch has been turned-off before heading upstairs in the evening because the switch is illuminated (the blades take awhile to spin down). The switch next to it is always on and although the simple rule of is the fan switch up or down applies, I get confused and the lighted switch reinforces my knowledge. And 3 Way Lighted Switches, I can tell if the light it controls is on or off without need to see the light itself.

So, without further ado, here’s my lighted switches.

 


Set #1. Upstairs Switch for Bottom of stairs and upstairs hallway. We used clear switches for the bottom of stairs light in both places to reinforce the location of each light.

 

Set #2. This is the living room ceiling fan switch, it’s a variants from the others in that the moveable part is not illuminated; a clear border around the moveable part is; and the switch is green. It’s not very bright, but when dark is noticeable, the image doesn’t do it justice. This switch plate is old but never used. Had it in supplies from my father and I’m sure he had it from long ago.

 

Set #3. Bottom of the stairs switch for Bottom of stairs and upstairs hallway. As stated in #1, we used clear switches for the bottom of stairs in both places to reinforce the location of each light. This location features a special 3 Way switch with receptacle. The way we have it wired, the receptacle is unswitched, the switch above controls the light in the upstairs hallway.

 

Set #4. Bathroom. Receptacle is self testing, green light means OK, red light means tripped. The switch to its right is for the sconce lights, the switch to its right is for the ceiling light. Ceiling light is dedicated LED fixture and the sconce lights have LED bulbs in place of the incandescent ones. Lighted switches work just fine with them.

Not shown is the basement light switch.

A few points. Our switches are varied (color and style) because of changing circumstances and decisions during the rewiring that took, part time, 3 weeks.

One switch stopped working (not the light but the switch) after a few weeks. So I changed it, that’s how we ended up with the clear handle on the light switch in the upstairs hallway. And while changing it, I turned off its circuit but not the switch next to it, I got the worst shock I ever had across my chest when I touched the adjacent switch wiring screws. BE VERY CAREFUL around electricity. 25 years as an industrial electrician (worked around 15,000, 5000, and 480 volts and lower) and I let my guard down. Never do a job if you’re not familiar with electricity. Have a contractor do it if you’re not sure. Turn off all associated power.



A diversion and then more info on Meter and Tester Impedance.

They make a simple handy dandy tester for 120V Receptacles and Circuits, it’s a high value resistor and a neon bulb connected to the metal blade of a pocket screwdriver and mounted inside the insulated screwdriver handle, and the other side of the circuit is connected to the metal pocket clip or a metal tab at the top end of the screwdriver handle. The person holding it is part of the circuit. Against better judgement when seemingly sticking a screwdriver into a receptacle opening.

How to Use a ScrewDriver Neon Tester – Easy Way!



High input impedance meters cause something that is mostly particular to them, namely reading voltages (ghost or phantom voltages with only very small and insignificant currents) that aren’t actually in the circuit, but induced into it by adjacent wires. In industry, where a multitude of wires are run in common conduit, these voltages can be confusing, but I’ve never measured the entire amount of the voltage in adjacent wires induced into the wires of the circuit I’m working on, rather it’s not uncommon to be about 1/2 of the voltage, or 60 volts in the case of 120 volt adjacent wires. But, voltage is voltage, it’s presence can signal a variety of things, should not be dismissed, and must be assessed. The solution, in industry, is to use a meter with a low input impedance that doesn’t show these “phantom” or induced voltages, but would show the presence of an actual voltage. Likewise, the high input impedance meter can use an adapter to make it’s input impedance appear low to the circuit.

In an article on Wiki, they discuss hazardous and possibly deadly stray voltages found in the presence of high voltages but mention these phantom voltages that may be encountered during routine work at lower voltages:

Stray voltage

Coupled voltages

Since voltages detected by high-impedance instruments disappear or become greatly reduced when a low impedance is substituted, the effect is sometimes called phantom voltage (or ghost voltage). The term is often used by electricians, and might be seen, for example, when measuring the voltage at a lighting fixture after removing the bulb. It is not unusual to measure phantom voltages of 50–90 volts when testing the wiring of ordinary 120 V circuits with a high-impedance instrument. While the voltage produced may read almost to the full supply voltage, the capacitance or mutual inductance between the wires of building wiring systems is typically quite low and incapable of supplying significant amounts of current.

 

I’ve used all 4 of the above.

Upper left, Fluke Digital MultiMeter. Ghost voltages likely in certain environments. Meter measures voltage, continuity, resistance, and capacitance. Though in the regular voltage measurement mode ghost voltages are likely to be found, this particular meter offers a low impedance mode when in the VChek Mode (resistance setting), making this meter somewhat unique.

Upper right, Fluke T3 Tester. A tester often shows coarse voltages; 24, 48, 120, 208, 240, 277, and 480 AC and 6, 12, 24, 36, 48, 110, and 220 DC; rather than exact voltages of a digital meter, or nearly exact of an analog meter. On this tester, the higher the voltage, the more LEDs that illuminate, underscoring the relative danger of the voltage. This tester would be unlikely to show ghost voltages because of the input impedance. The tester will indicate AC or DC and continuity.

Lower left. Ideal Vol-Con Solenoid Style Voltage Tester. It shows the voltage by actively indexing a solenoid, and the solenoid vibrates, the more voltage, the more significant the vibration and the further the indicator moves. So there’s visual and tactile feedback of the presence of voltage and the level. The manufacture says this tester has a low input impedance. This tester would not show ghost voltages (that’s good). This specific model tester indicates AC or DC and continuity as well.

Lower right, Fluke Stray Voltage Adapter used to allow compatible meters, such as the one in the upper left, to be used to determine if ghost voltages or actual levels are present.



Author: Dr-Artaud

A Doctor that is not a Doctor, but named after a character in the movie "No Such Thing", as is the Avatar.

One thought on “Charm and Practicality of Illuminated Switches”

  1. another fabulous post ….tireless, informative and very useful even to a layman like myself.
    never been very good with electricity, or the principles of voltage, current and resistance, although I did study enough 10 years ago toward my HAM license….and have learned some basics about electric guitar electronics, and some knowledge pertaining to tube amplifiers….not a whole lot mind you, but this post is a wonderful piece of information with beautiful pictures….thanks !!

    Liked by 1 person

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