convert one way switch to three and extend circuit


  #1  
Old 07-28-16, 08:23 AM
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convert one way switch to three and extend circuit

We are re-doing a small entrance room to add a new front door.
There is an existing switch, which powered the inside lights and the outside light.
I want to add an extra switch inside the room and make it 3 way but also extend the circuit.

I have 2 main questions:
1/ The 2 switches inside the room will now be on a 2 gang. Are the box space requirements enough to hold all these wires. I think it will be 7 conductors plus 2 switches + ground = 10 conductors of 14/2 wire? 24 cu.in required? Single gang is normally 12.5?
Do the conductors going between the switches count?

2/ How can I get power to the receptacle in the corner on this circuit but bypassing the switches as each run of power goes to the switches first.

Existing layout:
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Proposed layout
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  #2  
Old 07-30-16, 04:47 PM
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  #3  
Old 07-30-16, 06:01 PM
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I looked at your second diagram and couldn't figure it out. I have marked some of the things I don't understand.

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Old 07-30-16, 06:39 PM
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The furthest left is a thermostat and a heater.
The 3 switches I guess I didn't draw correctly because they power other lights that aren't in the diagram. The switch I want to change is the 3rd switch ( on the right) of those 3 switches.

By always hot do you mean a switch loop? What I'm trying to show is that I will have 2 c wire nmd from the switch to the porch light.
 
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Old 07-30-16, 07:22 PM
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By always hot do you mean a switch loop?
No a switch loop is a switched power. Always hot means it is always on. You seem to show the porch light taking power from the common of the 3-way switch. That means the 3-way circuit would have to be on to power the porch light.
What I'm trying to show is that I will have 2 c[onductor] wire nmd from the switch to the porch light.
But you are not showing a power source for it. The 3-conductor cable has no always hot wire for the porch light.
 
  #6  
Old 07-31-16, 03:33 AM
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So, if in the back of the junction box, I connect in parallel to provide individual power to the 2 switches that should be OK? Then pigtails out to the switches?

So, in this example I make a pigtail for the 1 black source on the left switch.
But then how do I pigtail the second 3 way to provide power for the 1 way porch right next to it?

http://i.stack.imgur.com/UiRe2.gif
 

Last edited by qwertyjjj; 07-31-16 at 06:29 AM.
  #7  
Old 07-31-16, 11:57 AM
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I connect in parallel to provide individual power to the 2 switches that should be OK? Then pigtails out to the switches?
Yes.
switch.
But then how do I pigtail the second 3 way to provide power for the 1 way porch right next to it?
You can't. You don't have a source of always on power at the box. You will need to run another cable to the box on the right to power the porch light.
 
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Old 07-31-16, 04:00 PM
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Hmm.
It might be difficult to fit 2 nmd wires through the current concrete hole.
I guess I could also go round the back through the holes for the heater cable, to the receptacle, then to the light, then to the single switch.
 
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Old 07-31-16, 05:10 PM
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If I take a different route and go power source to the light first, will I need 2 nmd cables coming from the porch light to the switch? Or is that when I use a switch loop.
My problem is that the junction box for the porch light is on the outside so wires have to go through concrete first.
 
  #10  
Old 07-31-16, 05:37 PM
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Or is that when I use a switch loop.
Before 2011 that would have been the most common answer. You can still use a switch loop but you will need to use under current code 3-conductor cable if you do. You need 3-conductor because a neutral is code required at the switch even if you don't need it. Most electricians now will just run power to the switch first and just a single 2-conductor cable to the light. Saves having to use a 3-conductor cable.

No, the neutral of the 3-way can't be used to satisfy the neutral requirement for the porch light because it wouldn't be in the same cable sheath as the hot for the light.
 
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Old 07-31-16, 08:12 PM
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So, in the diagram I either have to
- put a 3 wire and a 2 wire from the 3 box to there 2 box OR
- take a 2 cable wire to the receptacle then over the ceiling to the switch then back over the ceiling to the light.
That's a lot of extra cable.
 
  #12  
Old 07-31-16, 09:17 PM
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have to
- put a 3 wire and a 2 wire from the 3 box to there
No a two conductor to the light from a power source and a 3-conductor from the light to the switch.
OR
- take a 2 cable wire to the receptacle then over the ceiling to the switch then back over the ceiling to the light.
Yes.

There are alternate methods such as running a 4-conductor cable instead of a 3-conductor cable between the right and left switches or running ENT with 4 wires plus a ground between the switches and a two conductor cable to the porch light.

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Last edited by ray2047; 07-31-16 at 09:46 PM.
 

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