3-way switch question (sw-light-sw)
#1
08-24-15, 01:52 PM
3-way switch question (sw-light-sw)
When you look at a drawing of two 3-way switches with the light fixture in between, there doesn't seem to be a return wire from the second switch. The white from switch one ends at the light fixture and the white from switch two becomes a white-painted-black and wirenuts back to the red wire that connects to switch one.
Am I correct? Is this the best way to do this?
Is it correct that you cannot do sw-light-sw beginning with the 2011 NEC if there is no neutral wire in the switch boxes? If so, what do you do?
Gary
Am I correct? Is this the best way to do this?
Is it correct that you cannot do sw-light-sw beginning with the 2011 NEC if there is no neutral wire in the switch boxes? If so, what do you do?
Gary
#3
08-24-15, 04:06 PM
Group Moderator
There are many ways to wire a three way circuit. In my diagram is the ideal way. Power comes in at one switch and the lights connect at the other switch. There is neutral at both boxes.
#4
08-24-15, 07:05 PM
I now see that my first description was wrong.
Here is my configuration. The white from the panel ends at the light fixture and the white from switch two becomes a white-painted-black and wirenuts back to the black wire that connects to the corresponding screw on switch one. Is this out of code as of NEC 2011?
Here is my configuration. The white from the panel ends at the light fixture and the white from switch two becomes a white-painted-black and wirenuts back to the black wire that connects to the corresponding screw on switch one. Is this out of code as of NEC 2011?
Last edited by GaryMN; 08-24-15 at 07:51 PM.
#5
08-24-15, 07:49 PM
Why do you want the light between the switches. The way PJ shows meets code and is easier.
Three thoughts on that:
The diagram you posted would meet 2011 code if you used a 4-conductor cable instead of a 3-conductor cable to the second switch.
except on another drawing the white from switch one ends at the light fixture and the white from switch two becomes a white-painted-black and wirenuts back to the red wire that connects to switch one.
- The NEC does not specify colors used on 3-way. It is Installers option.
- The NEC requires a white not used as a neutral be remarked any color but green or gray.
- As to "white from switch two becomes a white-painted-black and wirenuts back to the red " Not sure I understand. I'd need to see the diagram but it may have to do with where the power comes in.
The diagram you posted would meet 2011 code if you used a 4-conductor cable instead of a 3-conductor cable to the second switch.
Last edited by ray2047; 08-24-15 at 08:17 PM.
#6
08-24-15, 08:13 PM
The first switch is original with the house. It is 3-wire, run inside a sheetrock wall, located near the house entrance from the garage. It leads to a ceiling-mount light fixture, I'm trying to locate a second 3-way switch near the other door at the opposite side of the garage.
Thanks for the markup showing 4 wires. In box two, what do you do with the white wire?
Thanks for the markup showing 4 wires. In box two, what do you do with the white wire?
#7
08-24-15, 08:19 PM
Group Moderator
You already have the three wire cable from your original switch to the light. You are converting that cable to operate a three way switch system.
That begs the question...... what is that three wire cable doing now ? Why was three cable run if all three conductors weren't in use.... a spare ?
That begs the question...... what is that three wire cable doing now ? Why was three cable run if all three conductors weren't in use.... a spare ?
#8
08-24-15, 08:50 PM
good question
Pete, the red was just wire-nutted inside the ceiling box. I am the third owner of this house and wasn't around when it was done. I assume the electrician needed to go get more wire, a switch and a handy box, but it was Friday afternoon and Miller Time and ... now it is 25 years later and I just discovered the situation. I would like to add the second switch.
#9
08-24-15, 09:01 PM
Group Moderator
#10
08-24-15, 09:10 PM
what do you do with the white wire?
I assume the electrician needed to go get more wire, a switch and a handy box, but it was Friday afternoon and Miller Time and
It is 3-wire, run inside a sheetrock wall, located near the house entrance from the garage.
#11
08-24-15, 09:18 PM
So the white wire in the second box is for future use?
In my case would there be an easier way than what is shown in the diagram?
In my case would there be an easier way than what is shown in the diagram?
#12
08-24-15, 09:22 PM
So the white wire in the second box is for future use?
In my case would there be an easier way than what is shown in the diagram?
In my case would there be an easier way than what is shown in the diagram?
#13
08-24-15, 09:26 PM
Group Moderator
In my case would there be an easier way than what is shown in the diagram?
If you want to be code compliant..... you need to use four wire cable and follow Ray's diagram.
If you don't want to be code compliant you would use three wire cable and follow your diagram.
That's it.
#16
08-27-15, 11:26 AM
One rule is that the wire coming back to bring power to the light fixture (to its black lead or hot terminal) may not be white.
It is best to run the 3 conductor cable nonstop from one switch box to the other. If the best route goes to the light fixture then this cable can pass by the outside. Then run a 2 conductor cable from the second switch to the light. The result is topologically the same as PJMax' diagram above. This method avoids having to scrounge around for 4 conductor Romex.
It is best to run the 3 conductor cable nonstop from one switch box to the other. If the best route goes to the light fixture then this cable can pass by the outside. Then run a 2 conductor cable from the second switch to the light. The result is topologically the same as PJMax' diagram above. This method avoids having to scrounge around for 4 conductor Romex.
Last edited by AllanJ; 08-27-15 at 11:56 AM.
