3-way switch wiring -- so many ways!?

Posted by Percival P. Cassidy on October 14, 2009, 5:25 pm

On 10/14/09 04:27 pm, I wrote:

> John Grabowski wrote:

>>> http://www.homeimprovementweb.com/information/how-to/three-way-switch.htm
>>> shows 8 (eight!!) different ways of wiring 3-way switches.
>>> I am trying to figure out how the switches for our patio lights (two
>>> separate fixtures controlled by the same two switches) were wired.
>>> Each switch has two black wires and one red wire -- no white with
>>> black tape at either switch. There are neutrals (several, wire-nutted
>>> together) in each box, but they are not connected to anything else in
>>> the box. The only configurations shown at the above Web site with no
>>> black-taped white wires are Option 1 "Fixture Controlled by Two
>>> Switches: Power Through a Switch Box" and Option 5 "End-of-Run Lights
>>> Controlled by Two Three-Way Switches"; but I can't see what the
>>> difference is between those two configurations anyway.
>>> Any other possibility for 3-way switch wiring without black-taped white?

>> *Let's try a different approach. What are you trying to accomplish?
>> Are you having problems with the existing wiring?

> I am returning to a problem I posted here 4 1/2 years ago under the
> title "weird pilot light behavior." I couldn't find it again in Google
> except where it was reproduced at:
>

http://www.homegardenguides.com/garden-forum/home-repairs-forum/69787-weird-pilot-light-behavior.html

> To summarize:
> Both 3-way switches (one in the house, the other in the garage) operate
> the patio lights just fine, but I have been unable to understand the
> behavior of the integral pilot lights. NB: *pilot lights," which should
> be ON when the lights are on, OFF when the lights are off.
> I had not realized until a few days ago that there are so many possible
> configurations of 3-way switching. I posted my message here thinking
> that my lights and switches might be wired in an uncommon configuration
> that would explain the behavior of the pilot lights.
> The switches are Pass & Seymour/Legrand TM83PLICC with integral LED
> pilot lights. The circuit diagram shows one end of the LEDs connected to
> a silver-colored screw labeled NEU and the other end connected through
> resistors to each of the brass screws labeled 3W. There are also a black
> COM screw and a green screw with the standard Ground marking.
> I substituted these switches for the original ones that had no pilot
> lights and added the connections from the silver-colored screws to the
> whites in each box.
> The pilot light of the switch in the house is ON in one position of the
> switch, OFF in the other position of the switch, regardless of the
> position of the switch in the garage. The COMmon of this switch is where
> power is supplied to the circuit.
> The pilot light of the switch in the garage glows dimly, irrespective of
> the position of either switch -- except when there is no bulb in any of
> the fittings.
> The Pass & Seymour wiring diagram shows such a switch only at the point
> where power is supplied to the system but a note says that the switches
> can be used in both positions. HOWEVER, a message at
>

http://www.diychatroom.com/f18/wiring-diagram-three-way-switches-pilot-light-22868/index3/

> indicates that Leviton prescribes a different wiring arrangement when a
> pilot light is required at the load-common position

Ooops! Make that "line-common"

-- AND this requires

> not only an additional conductor between the two switches but also
> access to both of the pilot light connections (which the Pass & Seymour
> switches do not provide).

Perce

Posted by John Grabowski on October 14, 2009, 5:38 pm

>>> http://www.homeimprovementweb.com/information/how-to/three-way-switch.htm
>>> shows 8 (eight!!) different ways of wiring 3-way switches.
>>> I am trying to figure out how the switches for our patio lights (two
>>> separate fixtures controlled by the same two switches) were wired. Each
>>> switch has two black wires and one red wire -- no white with black tape
>>> at either switch. There are neutrals (several, wire-nutted together) in
>>> each box, but they are not connected to anything else in the box. The
>>> only configurations shown at the above Web site with no black-taped
>>> white wires are Option 1 "Fixture Controlled by Two Switches: Power
>>> Through a Switch Box" and Option 5 "End-of-Run Lights Controlled by Two
>>> Three-Way Switches"; but I can't see what the difference is between
>>> those two configurations anyway.
>>> Any other possibility for 3-way switch wiring without black-taped white?

>> *Let's try a different approach. What are you trying to accomplish? Are
>> you having problems with the existing wiring?

> I am returning to a problem I posted here 4 1/2 years ago under the title
> "weird pilot light behavior." I couldn't find it again in Google except
> where it was reproduced at:
>

http://www.homegardenguides.com/garden-forum/home-repairs-forum/69787-weird-pilot-light-behavior.html

> To summarize:
> Both 3-way switches (one in the house, the other in the garage) operate
> the patio lights just fine, but I have been unable to understand the
> behavior of the integral pilot lights. NB: *pilot lights," which should be
> ON when the lights are on, OFF when the lights are off.
> I had not realized until a few days ago that there are so many possible
> configurations of 3-way switching. I posted my message here thinking that
> my lights and switches might be wired in an uncommon configuration that
> would explain the behavior of the pilot lights.
> The switches are Pass & Seymour/Legrand TM83PLICC with integral LED pilot
> lights. The circuit diagram shows one end of the LEDs connected to a
> silver-colored screw labeled NEU and the other end connected through
> resistors to each of the brass screws labeled 3W. There are also a black
> COM screw and a green screw with the standard Ground marking.
> I substituted these switches for the original ones that had no pilot
> lights and added the connections from the silver-colored screws to the
> whites in each box.
> The pilot light of the switch in the house is ON in one position of the
> switch, OFF in the other position of the switch, regardless of the
> position of the switch in the garage. The COMmon of this switch is where
> power is supplied to the circuit.
> The pilot light of the switch in the garage glows dimly, irrespective of
> the position of either switch -- except when there is no bulb in any of
> the fittings.
> The Pass & Seymour wiring diagram shows such a switch only at the point
> where power is supplied to the system but a note says that the switches
> can be used in both positions. HOWEVER, a message at
>

http://www.diychatroom.com/f18/wiring-diagram-three-way-switches-pilot-light-22868/index3/

> indicates that Leviton prescribes a different wiring arrangement when a
> pilot light is required at the load-common position -- AND this requires
> not only an additional conductor between the two switches but also access
> to both of the pilot light connections (which the Pass & Seymour switches
> do not provide).

*The wiring is the same for any three-way set up: A line on one switch, the
load on the other and two travelers between the two switches. In your case
you have an additional neutral requirement due to the pilot light.

Don't compare the P&S to the Leviton switches. The wiring requirements for
the pilot light are different.

You didn't mention if the one pilot light that works actually comes on when
the load is on.

I'm not sure what the problem may be. Some thoughts do come to mind: The
switches are not wired properly. One of the switches is defective. P&S
goofed and later found out from the field and customers such as yourself
that their product does not work as intended.

If you are sure that the switches are wired correctly I suggest giving P&S a
call and see what they have to say on this issue. I looked on their web
site and could not find any wiring diagrams.

Posted by bud-- on October 15, 2009, 1:47 pm

Percival P. Cassidy wrote:

> John Grabowski wrote:
>

>> *Let's try a different approach. What are you trying to accomplish?
>> Are you having problems with the existing wiring?

>
> I am returning to a problem I posted here 4 1/2 years ago under the
> title "weird pilot light behavior." I couldn't find it again in Google
> except where it was reproduced at:
>
>

http://www.homegardenguides.com/garden-forum/home-repairs-forum/69787-weird-pilot-light-behavior.html

The original is:

<http://groups.google.com/group/alt.home.repair/browse_frm/thread/7ab08f84cb50b03b/d86b9b7a69028b1a?hl=en&q=%22TM83PLICC%22:alt.home.repair#d86b9b7a69028b1a>

>
> To summarize:
>
> Both 3-way switches (one in the house, the other in the garage) operate
> the patio lights just fine, but I have been unable to understand the
> behavior of the integral pilot lights. NB: *pilot lights," which should
> be ON when the lights are on, OFF when the lights are off.
>
> I had not realized until a few days ago that there are so many possible
> configurations of 3-way switching. I posted my message here thinking
> that my lights and switches might be wired in an uncommon configuration
> that would explain the behavior of the pilot lights.

All the diagrams from your web link are wired the same (as John said).
There are just variations in configuration depending on where the feed,
switches and light(s) are relatively to each other.

There are a couple other ways to do it.

> The switches are Pass & Seymour/Legrand TM83PLICC with integral LED
> pilot lights. The circuit diagram shows one end of the LEDs connected to
> a silver-colored screw labeled NEU and the other end connected through
> resistors to each of the brass screws labeled 3W. There are also a black
> COM screw and a green screw with the standard Ground marking.
>
> I substituted these switches for the original ones that had no pilot
> lights and added the connections from the silver-colored screws to the
> whites in each box.
>
> The pilot light of the switch in the house is ON in one position of the
> switch, OFF in the other position of the switch, regardless of the
> position of the switch in the garage. The COMmon of this switch is where
> power is supplied to the circuit.
>
> The pilot light of the switch in the garage glows dimly, irrespective of
> the position of either switch -- except when there is no bulb in any of
> the fittings.

This is not the same description, at either the house or garage, as in
your old thread.

Your old thread said the switches illuminated correctly with
incandescent bulbs but work strangely with CFLs. The switch illumination
depends on one of the "3W" terminals at each switch being pulled down to
neutral potential when the patio lights are off. It is pulled down
because the terminals connect only to an incandescent bulb which is a
relatively low resistance to the neutral. That is not true with CFLs
(and is why a number of devices, like timers, don't work with CFLs). I
would guess capacitance between wires becomes a major effect in what is
happening. Replacing one of the lamps with an incandescent should make
the switches illuminate correctly. If you have a "dimming CFL" you could
try that - I don't know how they are different.

--
bud--

Posted by John Grabowski on October 15, 2009, 4:43 pm

>>>> http://www.homeimprovementweb.com/information/how-to/three-way-switch.htm
>>>> shows 8 (eight!!) different ways of wiring 3-way switches.
>>>> I am trying to figure out how the switches for our patio lights (two
>>>> separate fixtures controlled by the same two switches) were wired. Each
>>>> switch has two black wires and one red wire -- no white with black tape
>>>> at either switch. There are neutrals (several, wire-nutted together) in
>>>> each box, but they are not connected to anything else in the box. The
>>>> only configurations shown at the above Web site with no black-taped
>>>> white wires are Option 1 "Fixture Controlled by Two Switches: Power
>>>> Through a Switch Box" and Option 5 "End-of-Run Lights Controlled by Two
>>>> Three-Way Switches"; but I can't see what the difference is between
>>>> those two configurations anyway.
>>>> Any other possibility for 3-way switch wiring without black-taped
>>>> white?
>>> *Let's try a different approach. What are you trying to accomplish? Are
>>> you having problems with the existing wiring?

>> I am returning to a problem I posted here 4 1/2 years ago under the title
>> "weird pilot light behavior." I couldn't find it again in Google except
>> where it was reproduced at:
>>

http://www.homegardenguides.com/garden-forum/home-repairs-forum/69787-weird-pilot-light-behavior.html

> The original is:
>

>> To summarize:
>> Both 3-way switches (one in the house, the other in the garage) operate
>> the patio lights just fine, but I have been unable to understand the
>> behavior of the integral pilot lights. NB: *pilot lights," which should
>> be ON when the lights are on, OFF when the lights are off.
>> I had not realized until a few days ago that there are so many possible
>> configurations of 3-way switching. I posted my message here thinking that
>> my lights and switches might be wired in an uncommon configuration that
>> would explain the behavior of the pilot lights.

> All the diagrams from your web link are wired the same (as John said).
> There are just variations in configuration depending on where the feed,
> switches and light(s) are relatively to each other.
> There are a couple other ways to do it.

>> The switches are Pass & Seymour/Legrand TM83PLICC with integral LED pilot
>> lights. The circuit diagram shows one end of the LEDs connected to a
>> silver-colored screw labeled NEU and the other end connected through
>> resistors to each of the brass screws labeled 3W. There are also a black
>> COM screw and a green screw with the standard Ground marking.
>> I substituted these switches for the original ones that had no pilot
>> lights and added the connections from the silver-colored screws to the
>> whites in each box.
>> The pilot light of the switch in the house is ON in one position of the
>> switch, OFF in the other position of the switch, regardless of the
>> position of the switch in the garage. The COMmon of this switch is where
>> power is supplied to the circuit.
>> The pilot light of the switch in the garage glows dimly, irrespective of
>> the position of either switch -- except when there is no bulb in any of
>> the fittings.

> This is not the same description, at either the house or garage, as in
> your old thread.
> Your old thread said the switches illuminated correctly with incandescent
> bulbs but work strangely with CFLs. The switch illumination depends on one
> of the "3W" terminals at each switch being pulled down to neutral
> potential when the patio lights are off. It is pulled down because the
> terminals connect only to an incandescent bulb which is a relatively low
> resistance to the neutral. That is not true with CFLs (and is why a number
> of devices, like timers, don't work with CFLs). I would guess capacitance
> between wires becomes a major effect in what is happening. Replacing one
> of the lamps with an incandescent should make the switches illuminate
> correctly. If you have a "dimming CFL" you could try that - I don't know
> how they are different.

*I had the CFL thought in the back of my mind, but did not look at the
original post. That is most likely the problem. Another device
dysfunctional as a result of CFL use.

Posted by on October 15, 2009, 7:34 pm

On Thu, 15 Oct 2009 16:43:51 -0400, "John Grabowski"

>>>>> http://www.homeimprovementweb.com/information/how-to/three-way-switch.htm
>>>>> shows 8 (eight!!) different ways of wiring 3-way switches.
>>>>> I am trying to figure out how the switches for our patio lights (two
>>>>> separate fixtures controlled by the same two switches) were wired. Each
>>>>> switch has two black wires and one red wire -- no white with black tape
>>>>> at either switch. There are neutrals (several, wire-nutted together) in
>>>>> each box, but they are not connected to anything else in the box. The
>>>>> only configurations shown at the above Web site with no black-taped
>>>>> white wires are Option 1 "Fixture Controlled by Two Switches: Power
>>>>> Through a Switch Box" and Option 5 "End-of-Run Lights Controlled by Two
>>>>> Three-Way Switches"; but I can't see what the difference is between
>>>>> those two configurations anyway.
>>>>> Any other possibility for 3-way switch wiring without black-taped
>>>>> white?

The red wire means everything is done with 3-wire cable - so the
"traveler" is red, not taped white. That is generally the "right" way
to do it. The white is never switched.

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3-way switch wiring -- so many ways!? - Page 3