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Ele - 3-way switch setup with 1 on 12/2 wire?

B

bczoom

Super Moderator
Staff member
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Is there any way to wire a 3-way switch with only a 12/2 wire on one of the switches?

For my workshop lights, they're switched at the main door. I would like to put another switch at the back door.

Access behind the existing switch/wall to pull a new wire would be a bugger so I'm looking for alternatives.

Right now, it's an in-line setup. Power supplied to single, existing switch.

If I removed the power to the existing switch and instead put the power to either the other switch (which will have 12/3 wire) or to the light in a switch-loop configuration, can I somehow use the 12/2 wire on the existing switch? I would then be missing a neutral wire for this switch.

I do have another switch in the existing box that controls other lights. Worse case scenario, I guess I could use the (2) 12/2's as a 12/3 and have all the lights come on at once but would really prefer not to... Partially because I want/need to do this again in another section of the building but I don't have a second 12/2 wire so I'm back to my first scenario above.

Thanks
Brian
 
S

Spiffy1

Huh?
SUPER Site Supporter
Put a pair in for the BIL a while back, I think they all required a 3wire configuration.

I think there might be a system you can buy with "remotes".

Else, any chance you can run 3 wire some how between the switches? Would external conduit be legal or allowed (the wife wouldn't complain?). The bulb doesn't need 3 wire, so you could still use the existing box then.

Most importantly: use my electrical advice as brainstorming only! I always make it work, but the things I do may not be recommended for any other application (or sometimes even that one :eek: ).

Better yet, you don't want switches.....you want the Clapper! :D
 
B

beds

New member
Your existing 12/2 wire from the switch to the light should be fine. You'll need to run 12/3 from the other switch to the existing switch, though. Not sure if that is possible.
 
OhioTC18

OhioTC18

Gone But Not Forgotten
GOLD Site Supporter
beds said:
Your existing 12/2 wire from the switch to the light should be fine. You'll need to run 12/3 from the other switch to the existing switch, though. Not sure if that is possible.
Click to expand...

bczoom said:
Access behind the existing switch/wall to pull a new wire would be a bugger so I'm looking for alternatives.
Click to expand...

That's his problem, no way to run new wire between them.
Brian, if there's no way to interconnect the switches, have you thought of something in the X-10 line?
 
DaveNay

DaveNay

Klaatu barada nikto
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bczoom said:
Is there any way to wire a 3-way switch with only a 12/2 wire on one of the switches?
Click to expand...

Yes. :thumb:

I have no idea if it is legal or to code though. :(

  1. Run a new circuit to the new three way switch.
  2. The hot goes to the switch.
  3. Run a 12-3 cable from the switch box to the fixture
  4. The Neutral runs through the box to the light fixture, on the new 12-3 white wire.
  5. The two legs of the three way switch goes to the ceiling on the other two wires of the new 12-3
  6. De-energize the existing switch circuit :whistle:
  7. Purchase a 10A SPDT solenoid relay with a 120VAC coil.
  8. Mount the relay in the ceiling near the fixture.
  9. Connect the two runners from the new switch to the two switched terminals of the relay.
  10. Run a wire from the common of the new relay to the light fixture (the hot leg)
  11. Connect the hot lead from the existing switch to the control coil of the solenoid.
  12. Connect the neutral of the existing switch to the control coil of the solenoid.
  13. Cross your fingers and double check everything and turn it on.
:weneedpic:weneedpic

The biggest problems might be 60Hz hum on the solenoid, and you will also be consuming extra power when the coil is energized.
 
johnday

johnday

The Crazy Scot, #3
SUPER Site Supporter
OhioTC18 said:
That's his problem, no way to run new wire between them.
Brian, if there's no way to interconnect the switches, have you thought of something in the X-10 line?
Click to expand...
Jerry, What is an X-10 line?:confused::tiphat::beer:
 
S

Spiffy1

Huh?
SUPER Site Supporter
X10

I think he needs to get one of the whole house control units, and have every light, appliance, and even his garbage disposal automated. :D

Actually, would be a great solution, perhaps even fairly cheap (barring the large control unit); it seems the remote ones I had in mind were a different brand, but same concept. Thanks for jogging my memory Jerry! :thumb:
 
BigAl

BigAl

Gone But Not Forgotten
SUPER Site Supporter
bczoom said:
Is there any way to wire a 3-way switch with only a 12/2 wire on one of the switches?

For my workshop lights, they're switched at the main door. I would like to put another switch at the back door.

Access behind the existing switch/wall to pull a new wire would be a bugger so I'm looking for alternatives.

Right now, it's an in-line setup. Power supplied to single, existing switch.

If I removed the power to the existing switch and instead put the power to either the other switch (which will have 12/3 wire) or to the light in a switch-loop configuration, can I somehow use the 12/2 wire on the existing switch? I would then be missing a neutral wire for this switch.

I do have another switch in the existing box that controls other lights. Worse case scenario, I guess I could use the (2) 12/2's as a 12/3 and have all the lights come on at once but would really prefer not to... Partially because I want/need to do this again in another section of the building but I don't have a second 12/2 wire so I'm back to my first scenario above.

Thanks
Brian
Click to expand...

Brian ,
There is a way to do it but it is illegal by electrical code standards . I won't even say how , in this thread . If you still want to know ,PM me .
Allen
 
B

bczoom

Super Moderator
Staff member
GOLD Site Supporter
I haven't done anything with it but do have a solution.

I have 2 pairs of 12/2 into the boxes. I'm going to use both to make my 12/3.

I was trying to avoid that solution as it now makes it where I'll loose the capability to use the separate switches to control which lights come on.
 
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