Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Lighting, Light Fixtures, Ceiling and Exhaust Fans
Reload this Page >

Trying to figure out 3-way/switch loop/double gang/multiple circuits wiring...

Trying to figure out 3-way/switch loop/double gang/multiple circuits wiring...


  #1  
Old 12-17-12, 10:14 AM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
Trying to figure out 3-way/switch loop/double gang/multiple circuits wiring...

Hello,

So long story short, we bought a house almost a year ago and I have been working on updating different things throughout. One thing I'm working on right now is some electrical in our dining room. I'm by no means an expert in electrical but at the same time, I have done my fair share of outlet/switch/thermostat/gfci/ceiling fan type wiring projects.

My problem in the dining room is trying to figure out all of the existing wiring and ultimately replace a couple switches (trying to add Insteon HA switches).

We have a double gang by our back door. One switch is a single-pole which controls our back porch light, but a second black wire is coming out of the bottom screw so I'm not sure what that is. The other switch in this box is one of the switches being used for the 3-way for the light above our dining room table. This is the switch I'm looking to replace.

On the other side of the room is the other 3-way switch which I'm looking to replace as well...and then on another wall there is yet another switch which controls a hallway light nearby. There is also an outlet on this wall which is somehow tied into this wiring as well.

Now I've heard different terms like "switch loop" and such, so I think that's what is going on here, but I can't wrap my head around it all.

Will someone let me know what info you need from me in order to walk me through switching out the two 3-way switches without losing power to any of the other switches/outlets please?

I've been trying all sorts of configurations, but just can't figure it out. THANKS!
 
  #2  
Old 12-17-12, 10:48 AM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
a second black wire is coming out of the bottom screw
One wire per screw and no back stabs is best. Use a pigtail there instead.

Just swapping out switches is easy. You don't have to understand the circuit just how the wires are connected to the switch and connect the new switch the same way. On a three way you have three terminals plus ground. The position of those terminals will vary with manufacturer so actually identifying which wire to which seminal not position on switch is the important thing to remember. Two of the terminals will have brass screws and those two wires should be marked "T" for traveler before disconnecting. They are interchangeable so which went to which brass screw isn't important. The third screw is an odd color usually dark gray or black. That wire should be marked "C" for common.

When connecting a new regular three way just connect the same terminal to terminal. With a specialty switch you may need to go a step further. One common wire is hot and is power in. The other is connected to the light. Once disconnected you can determine which common is hot by measuring to ground with a analog multimeter or test light but do not use a non contact tester. A specialty switch may also require a neutral on the same circuit as the light which you may or may not have.
 
  #3  
Old 12-17-12, 11:12 AM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
ray2047, thanks for your reply. Unfortunately, the switches I'm adding DO require a neutral. It looks like there are some neutrals in my first box (the double gang box), but the other 3-way switch doesn't seem to have a neutral. That's where I'm confused. Could it be a situation where the power is coming to the light fixture first? If so, is that what is called a switch loop? In a scenario like that, the neutral doesn't go to both 3-ways does it? Can I rewire it so that it does? Or just add another white wire to carry the neutral to both switches?
 
  #4  
Old 12-17-12, 11:38 AM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
What is the wiring at the light?

Any wiring done prior to NEC 2011 isn't likely to have a neutral in both switch boxes. On a switch loop and single gang box prior to 2011 code cycle if there is a neutral in one box it is not a switch loop.A switch loop won't carry the neutral to the switch box. I specified single gang because it is possible on a multi-gang box to have a neutral that is not part of the light circuit you are wiring. If you have a neutral at one switch box that is part of the light you wish to control then you can replace the 3-conducto (+g) cable between the switches with a 4-conductor(+g) cable.
 
  #5  
Old 12-17-12, 11:42 AM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 7,458
Upvotes: 0
Received 6 Upvotes on 5 Posts
My problem in the dining room is trying to figure out all of the existing wiring and ultimately replace a couple switches (trying to add Insteon HA switches).
Insteon makes remote control home automation (HA) controls. Is that what you're trying to install? A link to the specific switches you have would be helpful.

Unfortunately, the switches I'm adding DO require a neutral. It looks like there are some neutrals in my first box (the double gang box), but the other 3-way switch doesn't seem to have a neutral. That's where I'm confused. Could it be a situation where the power is coming to the light fixture first? If so, is that what is called a switch loop? In a scenario like that, the neutral doesn't go to both 3-ways does it? Can I rewire it so that it does?
All 3-way switch pairs operate by feeding power to one of the switches and attaching the load to the other switch. Most do not require a neutral in order to work. Having a neutral available in every switch is now a requirement in most jurisdictions, but that is a recent change.

If you tell us the number of cables, the number wires, by color, in each cable (omitting ground wires), and how each wire is connected, in each box, we can help you figure this out. Pictures taken with the switches pulled forward and the wires still connected might also help. See How To Put Pictures In Your Post.

Or just add another white wire to carry the neutral to both switches?
Only if you install a new cable that encloses the neutral for this circuit along with the other conductors. But we don't yet know if that's necessary.
 
  #6  
Old 12-17-12, 12:02 PM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
Ok, so it sounds like the best thing to do next is to get you guys some pictures. I'll take some tonight and post them later. Thanks for your help thus far, I hope we can get this all figured out! BTW, the Insteon's switches I'm looking to add are the switch ToggleLinc Dimmers (ToggleLinc Dimmer - INSTEON Remote Control Dimmer Switch, White - Smarthome).

Name:  2476dside4big.jpg
Views: 146237
Size:  31.6 KB
 

Last edited by ray2047; 12-17-12 at 12:43 PM. Reason: Add Diagram from member's link.
  #7  
Old 12-17-12, 12:37 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 7,458
Upvotes: 0
Received 6 Upvotes on 5 Posts
Thank you for the link. It appears, from the 3-way wiring diagram for that switch, that one of the switches will be connected to power but not controlling anything. The other switch will be controlling the light. It also appears that if you have a true neutral that is part of the circuit for your dining room light (as Ray noted) in either box, and you have a pair of travelers between the two switch locations - which you do - then you can do what you're trying to do without adding any wires.

I don't know how much these switches cost, but I'll bet it's more than a switch blank costs!
 
  #8  
Old 12-17-12, 12:48 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
I posted the diagram for all to see. While I suggested running the neutral between the switch boxes I see they run it from the light to the second switch box. That would avoid harder to find, more expensive 4-conductor cable. I like their solution better.
 
  #9  
Old 12-18-12, 04:47 PM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
Alright guys, got some pics for u.

Here's the double gang (3 different black/white cables and one black/white/red for the 3-way):
[ATTACH=CONFIG]6790[/ATTACH]


And then the other 3-way switch (one black/white cable and one black/white/red for the 3-way):
[ATTACH=CONFIG]6791[/ATTACH]
 
Attached Images   
  #10  
Old 12-18-12, 05:50 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 7,458
Upvotes: 0
Received 6 Upvotes on 5 Posts
Thanks for the pictures, but, since the wires aren't separated and the connections aren't visible, it's difficult to draw much information from them.

Which box has the line feed and which has the light load? Better yet, which cables and wires have those?
 
  #11  
Old 12-18-12, 08:46 PM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
Unfortunately, that's what I can't figure out. Is there any tricks to figure it out? I used my volt meter and found that one of the black wires coming into the double gang is out, but i don't understand how the other switch gets the power (traveler?) and I definitely can't tell what is going to the light. At one point I had it wired in a way I thought I was bypassing the single pole from the double gang and then it just resulted in only one of the 3-ways doing anything but it just turned the other hall light and outlet on/off...which is what made me start thinking it was all one big circuit somehow. Confused?!! That's why I'm here now..lol Please help!
 
  #12  
Old 12-18-12, 09:52 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 29,711
Upvotes: 0
Received 15 Upvotes on 13 Posts
Turn the beaker off. (Assumes light is connected to a black wire and a white wire.) Disconnect the black house wire from the light. Connect a long enough wire to to the house black wire to reach the switches. Disconnect the wires to the switch you are replacing. Use your multimeter to determine which of those wires in which switch box has continuity to the light. This is one common.

With your multimeter set to volts go to the switch box that you did not just identify a common in. Record all connection then disconnect the wires to the switch you are replascing. Turn the breaker back on and measure from each wire to ground. The wire with a 120v is the common for that switch box. . If you find two wires that measure 120 volts to ground then we will have to test further but you shouldn't. You only need to disconnect the wires to the switch you are replacing. Leave the other switch connected.
 
  #13  
Old 01-05-13, 05:28 PM
B
Member
Thread Starter
Join Date: Dec 2012
Location: USA
Posts: 6
Upvotes: 0
Received 0 Upvotes on 0 Posts
Well I finally figured it all out! Turns out the power WAS running to the light fixture first and then to the switches. I rewired the fixture and spliced power from a different switch so that power was entering the 3-way from there and then I was able to get the switches to do everything correctly! Thanks all!
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: