Three-way switch with on/off indicator
 

On Sat, 03 Jul 2010 19:27:45 -0500, "
wrote:

On Sat, 03 Jul 2010 13:52:24 -0400, mm wrote:

On Sat, 03 Jul 2010 09:51:24 -0400, Nate Nagel
wrote:

On 07/03/2010 08:12 AM, Gordon Shumway wrote:
On Sat, 3 Jul 2010 01:35:13 -0700 (PDT), Michael
wrote:

Somewhat OT. I have a regular switch for my outside light that lights
when the outside light is on. The curious thing is that my
electrician put it in using existing wiring and there is no neutral in
the box. The house is 70 years old and there are only 2 wires in the
box and the box is not grounded.. How is that possible?

If there are only two wires in that box one wire is hot and one wire
is common. You have no ground in that box. That's the way houses
were wired 70 years ago.

or one wire is hot and one is a switch leg, which IMHO is more common.

nate

Either way, his question was how does the light switch light when the
outside light is on?

No, the OP's question was:

"Are there three-way switches that have indicators (e.g. a light)
that tells you whether the circuit is on or not?"



Clare mentions a neon light, but they light when the outside light is
off.


The neon light I was talking about lighted with the light on - but I
was under the impression it required a separate dedicated neutral.
Apparently just a ground is legal.
It still "tells you whether the circuit is on or not". The neon is lit when
"not".

I can't answer Michael's question. Maybe someone can.

Maybe if you read the question as asked...

Three-way switch with on/off indicator
 

On Sat, 03 Jul 2010 23:04:44 -0400, wrote:

On Sat, 03 Jul 2010 19:27:45 -0500, "
wrote:

On Sat, 03 Jul 2010 13:52:24 -0400, mm wrote:

On Sat, 03 Jul 2010 09:51:24 -0400, Nate Nagel
wrote:

On 07/03/2010 08:12 AM, Gordon Shumway wrote:
On Sat, 3 Jul 2010 01:35:13 -0700 (PDT), Michael
wrote:

Somewhat OT. I have a regular switch for my outside light that lights
when the outside light is on. The curious thing is that my
electrician put it in using existing wiring and there is no neutral in
the box. The house is 70 years old and there are only 2 wires in the
box and the box is not grounded.. How is that possible?

If there are only two wires in that box one wire is hot and one wire
is common. You have no ground in that box. That's the way houses
were wired 70 years ago.

or one wire is hot and one is a switch leg, which IMHO is more common.

nate

Either way, his question was how does the light switch light when the
outside light is on?

No, the OP's question was:

"Are there three-way switches that have indicators (e.g. a light)
that tells you whether the circuit is on or not?"



Clare mentions a neon light, but they light when the outside light is
off.


The neon light I was talking about lighted with the light on - but I
was under the impression it required a separate dedicated neutral.
Apparently just a ground is legal.

That's as I understand it too, as long as it's in the leakage range.

...

Three-way switch with on/off indicator
 

bud-- wrote:

As RBM wrote "Pilot light switches are lit when the circuit is on, and
illuminated switches are lit when the circuit is off." Both of these
have the light in the handle of the switch (not a separate pilot light).

"Illuminated switches" are easy - as I said before you connect a neon
lamp between the traveler terminals If you work out the circuit, this is
the same as connecting a neon lamp across a single-pole switch.

"Pilot light switches" from Leviton require a neutral connection - I
believe that is true for all of them. They don't use a ground
connection. The circuit for one that I saw had resistors from each
traveler terminal to a common point. A neon lamp connected from that
point to a neutral.

Both of these use current through the load to light the neon lamp. If a
light bulb is burned out they will not work. They may or may not work
with fluorescents (CFLs).


In the Leviton system you describe, suppose R is the resistance of each
resistor in the voltage divider (between travelers). Suppose I is the
current of the neon indicator.

If the load bulb is burned out, the voltage divider will be between hot
and open regardless of switch positions. Voltage across the indicator
should be 120-IR. I would expect the indicator to glow.

If the bulb is burning, the voltage divider will also be between hot and
open. The indicator should glow as above.

If the bulb works but is switched off, the voltage divider will be
between hot and neutral (ignoring the bulb's small resistance). The
voltage across the indicator should be 60-(IR/2). I suppose the
indicator wouldn't light.

So it appears to me that load current is required not to turn the
indicator on but to turn it off.

Three-way switch with on/off indicator
 

Three-way switch with on/off indicator
 

J Burns wrote:
bud-- wrote:

As RBM wrote "Pilot light switches are lit when the circuit is on, and
illuminated switches are lit when the circuit is off." Both of these
have the light in the handle of the switch (not a separate pilot light).

"Illuminated switches" are easy - as I said before you connect a neon
lamp between the traveler terminals If you work out the circuit, this
is the same as connecting a neon lamp across a single-pole switch.

"Pilot light switches" from Leviton require a neutral connection - I
believe that is true for all of them. They don't use a ground
connection. The circuit for one that I saw had resistors from each
traveler terminal to a common point. A neon lamp connected from that
point to a neutral.

Both of these use current through the load to light the neon lamp. If
a light bulb is burned out they will not work. They may or may not
work with fluorescents (CFLs).


In the Leviton system you describe, suppose R is the resistance of each
resistor in the voltage divider (between travelers). Suppose I is the
current of the neon indicator.

If the load bulb is burned out, the voltage divider will be between hot
and open regardless of switch positions. Voltage across the indicator
should be 120-IR. I would expect the indicator to glow.

If the bulb is burning, the voltage divider will also be between hot and
open. The indicator should glow as above.

If the bulb works but is switched off, the voltage divider will be
between hot and neutral (ignoring the bulb's small resistance). The
voltage across the indicator should be 60-(IR/2). I suppose the
indicator wouldn't light.

Neon lamps are not like incandescents in that the voltage across the
lamp is essentially constant after the lamp has 'fired' (ionized the gas
and started conducting). And if the voltage is not high enough the neon
lamp will not fire on every half cycle.

60V may not be enough to 'fire' the neon lamp. Or, because the neon lamp
is at constant voltage, the drop across the resistors is much lower than
you expect and the current is relatively low - dim neon lamp


So it appears to me that load current is required not to turn the
indicator on but to turn it off.


Sounds eminently reasonable. I was 1/2 wrong.

If the bulb is burned out, (or maybe fluorescent), or switched
receptacle with nothing plugged in the switch won't indicate right.

--
bud--

Three-way switch with on/off indicator
 

On Mon, 05 Jul 2010 10:21:55 -0500, bud-- wrote:

wrote:
On Sun, 04 Jul 2010 12:00:44 -0500, bud-- wrote:

zzzzzzzzzz wrote:
On Sun, 04 Jul 2010 09:53:50 -0500, bud-- wrote:

"Illuminated switches" are easy - as I said before you connect a neon
lamp between the traveler terminals If you work out the circuit, this is
the same as connecting a neon lamp across a single-pole switch.
Yes, I mentioned the same thing, up there a while. I'm not seeing how this
works for 4-way, though. I remember having illuminated 4-ways in my parent's
house.
A 4-way has the 2 travelers traveling through the switch and swaps them,
or not, as they go through. Both kinds of 3 way switch handle light also
work on a 4-way if you connect to either of the traveler terminals.

I don't understand your second sentence, but looking at it again, it's clear
to me that there is a neon "drop" on each traveler from the voltage at the
"off" end. A neon between travelers at each 4-way will illuminate it and
there will never be more than two neon drops in the chain (always two - or
zero, with at least one 4-way).

Apologies for over-explaining.

The travelers are the 2 wires that connect between the 3-way switches.

Yes...

A 4-way switch has terminals A-B that connect to one 3-way switch and
terminals X-Y that connect to the other 3-way switch. In one position
the connections are A-X and B-Y. In the other switch position the
connections are A-Y and B-X. If you add 10 more 4-way switches, each one
just connects the travelers 'straight' through or 'swaps' them.

Yes...

If either 3-way scheme is connected to terminals A-B (or terminals X-Y)
inside a 4-way switch it is the same as connecting to the traveler
terminals on the 3-way switches. If you understand how pilot/illuminated
3-ways work you understand pilot/illuminated 4-ways.

Um...

The handles on both 3-way snitches, and all 11 4-way switches, will
glow or not glow the same. All the neon lamps are connected in parallel.

Ah! Yes, I see, the 3-way neon isn't across the switch, as it is with a SPST
switch, rather across the travelers like the 4-way neon connection. slap