Adding a pilot light to a 3-way switch

I would use a small neon panel lamp mounted in the corner of the switch plate. Keep in mind there may be code issues with anything of this nature so check local codes and do not proceed unless you know what you're doing. How to wire it depends on how the circuit is laid out, but you need one side to the neutral, and one side to the hot wire out to the light.

You can also get a pilot light which is designed to hold a standard C7 incandescent lamp and mounts in place of a wall switch, you could use an LED retrofit lamp in one of those, but it would require an additional gang in the junction box or a separate box. Again this isn't something you should try yourself if you aren't sure.

I don't think he can put a pilot light in a 3-way switch. The circuit will become unstable because two hot leads have to be connected to the pilot light. I suppose a couple of diodes could keep the circuit stability intact.

Having said that, I'm on board with the neon light too.

It depends on how the switch loop is wired. If one switch is a dead end (2 travellers and a switched return in the box) you could connect the neon to the switched return in both boxes. If this is wired the other way where the switches are in line carrying the neutral and 2 travellers the only place a pilot could be is in the far box.

Well like I said, it depends on how the circuit is laid out. In my house power comes in and the wire goes out to the light from the same box, then a 3 conductor cable runs from that box to the remote switch, so adding a pilot to the master switch is easy, adding it to the remote switch would require an additional wire. I've seen some 3 way arrangements where power enters at one switch box and the light comes off the other switch, as well as one that had power entering the light fixture box and then a separate switch drop, that's the hardest to add a pilot to.

I don't know where you're going with the stability and diodes thing, none of that is necessary, you wire the pilot light up across the wires going out to the light fixture. Perhaps you're thinking of an illuminated switch? That's different than a pilot light, though it could also be added if things are laid out favorably.

Yes, I was thinking of an illuminated switch. Isn't that a pilot light?

What's a pilot light if not an illuminated switch?

A pilot light illuminates when the switch is on to let you know that a remote light is on, an illuminated switch lights up when the light is off so you can find the switch in the dark.

...which means that a standard 3-way lighting circuit cannot have a pilot light on one of the switches without either running additional wires or sensing current.

Consider the four possible states of this standard 3-way circuit:

(Best viewed with a monospace font such as Courier)

We start with the lights on:

LINE A O----------O / \\ HOT-----O O-----(LIGHTS)-- LINE B | O----------O LIGHTS | STATE #1 ARE ON | | NEUTRAL--------------------------------

Someone switches the rightmost switch, thus turning off the lights:

LINE A O----------O / HOT-----O O-----(LIGHTS)-- LINE B / | O----------O LIGHTS | STATE #2 ARE OFF | | NEUTRAL--------------------------------

Someone switches the leftmost switch, thus turning on the lights:

LINE A O----------O HOT-----O O-----(LIGHTS)-- \\ LINE B / | O----------O LIGHTS | STATE #3 ARE ON | | NEUTRAL--------------------------------

Someone switches the rightmost switch, thus turning off the lights:

LINE A O----------O \\ HOT-----O O-----(LIGHTS)-- \\ LINE B | O----------O LIGHTS | STATE #4 ARE OFF | | NEUTRAL--------------------------------

Someone switches the leftmost switch, thus bringing us back to state #1.

The pilot light for the rightmost switch is easy; just wire it in parallel with the lights being controlled. The wire between the rightmost switch and the lights is hot when the lights are on.

The pilot light for the leftmost switch has a problem: none of the three wires going to the switch is hot only when the lights are on. In fact, all the voltages on all three wires going to the leftmost switch are the same in state #1 and state #2. No clever arrangement of diodes will allow the pilot light to tell the difference between states #1 and #2.

So if you really need a pilot lamp on the leftmost switch, you need to either run an additional wire back from the rightmost switch, or you need to sense current, not voltage. A properly sized current sense transformer would allow sensing the current. It would also make the pilot light a detector of a burned out or unscrewed bulb in the light being controlled by the 3-way switch.

--
Guy Macon

Okay, I get it.

I was thinking of an illuminated switch so one could find it in the dark.

Ï "Guy Macon" Ýãñáøå óôï ìÞíõìá news:hqGdnR6dyctByNPVRVn snipped-for-privacy@giganews.com...

No idea about the OP's question, wonder why he used Chinese encoding in his post. In Greece, we call 3-way switches aller-retour (French), and there's a design with 3 switches, 2 3-way and 1 4-way.

--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr

Sounds like an illuminated switch (lighted when off) might work. I believe illuminated 3-ways connect a neon lamp between the travelers.

If a commercial combination is not available one way to do this in a single opening is to use Despard devices, which are interchangeable devices that mount on a strap with 3 openings. You could combine a standard switch, a 3-way switch and a *neon* pilot light unit. Wire the neon light across the 3-way travelers. You could have a light at each end. The light will be on when the switched load is off. There needs to be some load to light the neon light. Google for Despard. If you are at the load-end 3-way, and a neutral is available, you can connect the light across the load as a pilot light.

I would not recommend do-it-yourself. You might be able to find space for a UL listed commercial pilot light unit with leads.

You could try the question at alt.home.repair. There are several good electricians and some other sharp people. Someone might know of a commercial device.

--
bud--

Then go back to the light switch store and tell the guy that that's what you were looking for in the first place. Tell him, "Oops!". :-)

Cheers! Rich

Look in the catalogs... e.g. Hubbell HB1203PL. Stock item at Grainger and probably at the big electrical suppliers if you give them the part number :-).

Tim.

I'm not the one that was asking for it, I'm one of the people that attempted to give an answer based on my false assumption/misunderstanidng of the device being sought.

Content-Transfer-Encoding: 8Bit

Tzortzakakis Dimitrios wrote:

Like this:

O----------O O----------O / \\ HOT-----O / O-----(LIGHTS)-- \\ / | O----------O O----------O | 3-WAY 4-WAY 3-WAY | | NEUTRAL-----------------------------------------------

...and, of course you can add as many of the 4-ways as you wish, using 3-ways at each end.

In the above case, only the rightmost switch can have a pilot light

Ever so often, some home handyman who doesn't know about the

4-way version buys three 3-ways and then spends the next four hours trying to figure out why he can't wire it correctly. :(

--
Guy Macon

That won't work on one of the ends. Neon lamps are voltage devices, and all the voltages at the switch closest to the main stay exactly the same as the switch closest to the load is toggled. See my post with wiring diagrams.

I wouldn't advise that. It will be hard to find replacements. Better to redo the box to allow standard devices.

--
Guy Macon

Thanks to all of you who replied to my question.

I think I'll settle with a neon lamp since it's easy to find 120v neon lamps while 120v LED is hard to find.

I'm replacing an existing standard switch with two 3-way switches so I can control the attic fan from 2nd floor also. That means I can decide which is the rightmost and leftmost switch in Guy's drawing (BTW, thanks for taking time to draw the diagram).

So, the hot of the rightmost switch goes to, in addition to the attic fan, a 47K Ohm resistor, a neon lamp then to the neutral of the other switch (the standard switch in the stack switch) because the 3-way switch doesn't have a neutral.

Thanks again to everyone.

Just get a neon lamp which is already a finished assembly with a resistor and all, you can pick them up at Radio Shack among other places, then just drill a hole and mount it. If you're adding the second switch yourself, you can run an additional wire to put the pilot light in either or both locations.

You can also get thermostats designed specifically to run attic fans automatically.

Years ago I added a pilot light to a similar situation at my parent's house. See thus: O----------O O----------O / | / \\ HOT-----O | / O-----(LIGHTS)-- | / | O----------O O----------O | 3-WAY | | | R R | | | | +___+ | | | NEON | | | NEUTRAL---------+------------------------------------- Resistors "R" were around 100k, and the neon light an NE-2 equivalent. When the lights are off, the neon light sees 1/2 the line voltage, divided by the resistors. When the lights are on, then one of the resistors floats (except for capacitance of the wiring), and the other drives the neon light. This depends on the non-linearity of the neon light: at 1/2 line voltage it either fails to light, or just barely comes on.

-Mark

If there is a load (like a light bulb or fan), and the switches are in an off combination, there will always be 120V between the travelers (the

2 wires connecting the switches). A neon light connected between the travelers will light up. That works at both ends. It works when 4-way switches are added. It works when wired with the with the less common "California 3-way" setup.

Despard devices *are* "standard devices" available from several manufacturers. They have been around for a real long time. Even Roy can find them.

--
bud--