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4 wire problem

2K views 7 replies 5 participants last post by  andrew79 
#1 ·
I had a light switch that didn't do anything. It was the third light switch in a group of three. The other two work just fine.
When I took the switch plate off and started to try figure out what the third switch is supposed to control I found a red wire coming out of the back that was live. All of the rest of the wires that control the lights in my house are 3-wire, but this one is a 4-wire (black, white, red and ground).
Can someone please explain what the red wire is for? All of the other lights that are powered by the line work just fine even if the red wire is not connected to anything. I want to use the third light switch, but right now it does nothing but house the red wire.
Hope I have explained enough.
Can I just cap the red wire?
 
#2 ·
need more info
what wires are going to each of the three switches
are there any joints in the box
Are all the switches single pole or are any of them threeways.
what room of the house is it located in
 
#4 ·
ive seen something like that when i helped my friend to do some renovations in his house.

It turned out what the electrician did was instead of running 2 seperate 14-2 wires(black,white,ground), he did the lazy way and ran a 14-3 wire(black,red,white,ground).

So the red wire is acting like another black(hot) wire. Less time, and less effort in running another wire.
 
#6 ·
andrew79

I'll do my best to answer you questions.

what wires are going to each of the three switches - The first light switch has the black wire going into the bottom of the switch and then feeds into a hallway light.
The second switch has a black wire feeding from the first switch on the bottom and that switch controls an outdoor porch light.
The third switch has a black wire feeding from the second switch on the bottom and the red wire from the main line (4 wire) attached to the top.

are there any joints in the box - Not sure what you mean by joints - sorry.

Are all the switches single pole or are any of them threeways - All of the switches are single pole. None are three way.

what room of the house is it located in - This is located in the front hallway/dining room.
 
#8 ·
andrew79

I'll do my best to answer you questions.

what wires are going to each of the three switches - The first light switch has the black wire going into the bottom of the switch and then feeds into a hallway light.
The second switch has a black wire feeding from the first switch on the bottom and that switch controls an outdoor porch light.
The third switch has a black wire feeding from the second switch on the bottom and the red wire from the main line (4 wire) attached to the top.

are there any joints in the box - Not sure what you mean by joints - sorry.

Are all the switches single pole or are any of them threeways - All of the switches are single pole. None are three way.

what room of the house is it located in - This is located in the front hallway/dining room.

i was curious about any other wires joined together as i wanted to know the the whites in the box were used as neutrals or as switch legs. If i understand you correctly you actually have two wires joined on the same screw on some switches and this is a no no. Where the black wire that comes from the 4 wire is attached will tell the story better...If it's been hooked up to always be on then the other posters assesment of a plug without the tab broke is more than likely your best bet.
 
#7 ·
The red sounds like it was a switched hot. Since you say it is hot I am going to assume that someone may have changed out a receptacle and not broken the tab between the brass screws.

This switch may have been for a switch controlled receptacle.

A joint that was asked about would be a splice between 2 or more wires.
 
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