Electronic switch to re-purpose dead end 3-way?

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Greetings all I have a typical 'dead end 3-way' switch at the end of a hall in a existing modern house with limited access no attic etc(call this box B)
The customer would like to add a light directly above this switch box, but since its a dead end 3 way, we'll be running a cable to tie into the main switchbox (call it box A).

I have 2 design rules for permanently installed, hard wired electrical devices:
1) They shall not rely on a battery for primary operation.
2)They shall not have any reliance on WIFI or 'wireless' anything for primary operation.

I seem to recall a dimmer or a switch that could use a single wire to communicate, freeing up the white wire in the 14/3 to be used as a neutral.
I am a only finding current products (looked at Lutron) that use either batteries or wireless which like I said I'd like to avoid.
Thanks in advance
 

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Todd0x1

Senior Member
Location
CA
As antequated as they are, this sounds like a job for X10 switches. You could put a master switch in box A and a companion switch in box B. Companion switch needs a hot + 1 addtl wire, which leaves you a neutral for your new light.
 

rainwater01

Member
Location
Greenwood Indiana
Occupation
Electrician
I would recommend this over x-10. It’s very reliable. It sends two signals simultaneously. One over the power line and one wirelessly.


I looked at some Lutron stuff but even if the switch doesn’t require a neutral the light will, so you need four wires unless you can find another Lutron or similar device that communicates with one wire instead of two. Sorry I’m not aware of any.


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Todd0x1

Senior Member
Location
CA
I would recommend this over x-10. It’s very reliable. It sends two signals simultaneously. One over the power line and one wirelessly.


I looked at some Lutron stuff but even if the switch doesn’t require a neutral the light will, so you need four wires unless you can find another Lutron or similar device that communicates with one wire instead of two. Sorry I’m not aware of any.


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The particular X10s I am talking about don't use the x10 signal, the companion switch has a wire to the master switch -no wireless or powerline signals involved.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Greetings all I have a typical 'dead end 3-way' switch at the end of a hall in a existing modern house with limited access no attic etc(call this box B)
The customer would like to add a light directly above this switch box, but since its a dead end 3 way, we'll be running a cable to tie into the main switchbox (call it box A).

I have 2 design rules for permanently installed, hard wired electrical devices:
1) They shall not rely on a battery for primary operation.
2)They shall not have any reliance on WIFI or 'wireless' anything for primary operation.

I seem to recall a dimmer or a switch that could use a single wire to communicate, freeing up the white wire in the 14/3 to be used as a neutral.
I am a only finding current products (looked at Lutron) that use either batteries or wireless which like I said I'd like to avoid.
Thanks in advance
I know this violates your rule #1 but I would use a Lutron dimmer with a PICO unit at the end where you are cannibalizing the conductors. It will look like the real deal and give you full dimming at both ends and the battery will last for years. Also not some unreliable crap.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
This could also be done by replacing the 3-way switch in box B with a normal SPST switch along with a relay connected to box A. {And for all I know, that's what the above X10 leader/companion switches are doing.] The 3 wires from B to A are then neutral, hot, and a return switched hot from B. The relay common, NC and NO contacts play the role a 3-way switch, and the relay coil is energized by the return switched hot from B.

It would be nice if a manufacturer packaged the relay plus 3-way switch all on a single yoke. It would just need L, N, remote switched L, and Load connections. Maybe someone makes this and I just don't know it.

Cheers, Wayne
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
You could use a Lutron Maestro C-L/LED+ dimmer at the main switch location, and have a mechanical switch at the present dead-end location (as shown below and on pg. 4 of the document at the link below). In this configuration the switched/dimmed hot is available for having lights at both locations with only a 3-wire connection between them. This mode will have to be programmed into the dimmer with its buttons.

Maestro_3-way_with _mech_sw.png
https://www.lutron.com/TechnicalDocumentLibrary/369613a.pdf
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
That would give you the ability to add a new light at the current dead-end location that is controlled by both existing switches. I'm under the impression that the OP wants to have a new light controlled by a separate switch at the current dead-end location. But perhaps I'm mistaken.

Cheers, Wayne
 

rainwater01

Member
Location
Greenwood Indiana
Occupation
Electrician
That would give you the ability to add a new light at the current dead-end location that is controlled by both existing switches. I'm under the impression that the OP wants to have a new light controlled by a separate switch at the current dead-end location. But perhaps I'm mistaken.

Cheers, Wayne

Possibly but his picture only shows one switch on each end.


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wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Possibly but his picture only shows one switch on each end.
Good point, so my earlier comments are probably off the mark. It which case it's not enough to just "free up a white wire" for the neutral, it's also required to provide the final logical switched hot at the current dead-end.

Cheers, Wayne
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Greetings all I have a typical 'dead end 3-way' switch at the end of a hall in a existing modern house with limited access no attic etc(call this box B)
The customer would like to add a light directly above this switch box, but since its a dead end 3 way, we'll be running a cable to tie into the main switchbox (call it box A).
Just to clarify, are you looking t have the new light work simultaneously with the existing light, and keep the 3-ways working as they are now? If so, you're correct that you need four conductors to hard-wire it normally.

The old X-10 3-way system uses what's called a "companion" switch as a wired remote for the main switch. The two blue wires are internally connected (to make installing it easier) so you can wire it like below, join them, or cap one.

You could install the main switch at box A, and have it's black feed both the existing light and the 3-conductor's black to feed the new light (and the companion's . Use the white as the neutral, and the red as the control.

Use this diagram. Mentally add the neutral and your existing light at the master, and you can see that three conductors will suffice. Be aware that theses devices use TRIACs and were originally designed for incandescent lighting.

1634089553064.png
 
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wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
So how do the WS477 CS277 together use the red wire to cause the (connected) CS277 Blue wire and WS477 Black wire to enter the proper switched state based on the two switch settings?

Cheers, Wayne
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I'm not sure I understand your question.

The WS is dependent on trickle current through the load, which incandescent loads provide. That keeps the WS circuitry fed.

The CS connects the red to the blues (fed through) to activate the WS which apparently mimics pressing the button on the WS.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
OK, say the load is on (the blues on the CS are energized), and you touch the button on the CS (apparently it's momentary)? That provides a power pulse on the red that the WS can notice, and turn the load off.

But now the load is off, and the blues are unpowered. How does the WS detect when you press the CS button again and momentarily short the blues to the red? Is it constantly trickling a small current through the load, even when "off", so that it can detect the small power pulse on the red? E.g., it's switching between, say, 100% power and 0.1% power?

Cheers, Wayne
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Is it constantly trickling a small current through the load, even when "off", so that it can detect the small power pulse on the red? E.g., it's switching between, say, 100% power and 0.1% power?
It is. That's why the WS has the full-off slide tab at the bottom (UL).

It will even work with the WS and CS in swapped positions.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
OP hadn't come back since first post to comment on suggestions so I'll comment, I don't see how any suggestion so far have provided the ability to power 2 fixtures each being wired to opposite ends of the existing 3 way switching supply that OP wanted to do.

Here is a situation you need to control lighting from 2 locations, existing is only giving a 3 wire that has to make the white neutral into an ungrounded conductor, and essentially giving no neutral in the second box location an thus no neutral for the new secondary light fixture. If cutting and pulling in new wire (maybe like a 14/2/2) is not an option you are left with going wireless.
Even @LarryFine illustration in post #13 is not providing a neutral as it would still need to be reassigned as a ungrounded conductor for a return to the original fixture to be switched.

Sometimes a customer can't have everything they want.
Of course there is the third option, get a handiman to install.
He will (in violation of code) reassign the ground as a neutral in the 14/3 NM then leave everything untouched.
DO NOT DO.
But have seen it done by a handyman. And of course the HO will ask "Why not, the lights came on?"
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Even @LarryFine illustration in post #13 is not providing a neutral as it would still need to be reassigned as a ungrounded conductor for a return to the original fixture to be switched.
It will work. The original light gets its neutral in box A. The white wire to box B is not shown in the diagram.
 

rainwater01

Member
Location
Greenwood Indiana
Occupation
Electrician
Actually synchro’s post #9 would work because it wouldn’t need a switched leg returning from the second switch. It can be tapped into at switch one before it leaves.

The x-10 works too but it warns against using led unless that’s a different application and Insteon works but it’s not physically wired to switch 2.


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