# Light Switch Replacement Question



## dtheobald (Nov 18, 2011)

I am replacing some of my old light switches. They are like decora switches, but the button is the full size of the switch plate. They are horrible. I boutgh new switches and covers to do the job a little at a time...as my house has arouns 25 of these horrible switches. 

Anyway...I turned the power off at the breaker box and removed the switch plates and pulled out the old switch on a double switch box. One of the switches only had 2 lines going to it...the other had 3 lines going to it. This confused me a bit, so to be safe I thought I would try to ask around and do some research. 

THese are not on dimmer and to the best of my knowledge, they are not 3 way switches. 

Any idea why one switch has 3 wires, the other only 2???


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## joecaption (Nov 18, 2011)

If there's one black screw, two gold screws,  and a green for ground it's a 3 way switch.
As you remove the wires do them one at a time and connect it to the new switch so you do reverse one of the wires.
No idea why there would be three wires if it's not a three way. Sometimes it goes to a wall outlet not a light.


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## dtheobald (Nov 18, 2011)

That could be it, it does control a Ballast for 3 flourescent bulbs, but they both do. maybe the ballasts it powers are plugged in somewhere...THe house does have 'lamp switches' as I call them. I really dont think it is a three way switch...if it is, I cant find the other switch?


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## nealtw (Nov 18, 2011)

Does each wire have it's own screw?


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## JoeD (Nov 19, 2011)

This has nothing to do with the ballasts. If the switch had three screws it is a three way switch. There is another switch that also controls this same light. 
'Please describe the switch and what it controls. Is there another switch that also controls the same thing?


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## joecaption (Nov 19, 2011)

Three way swithes have 4 screws not 3.
Three for the hots and one for ground.


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## JoeD (Nov 19, 2011)

Switches in Canada don't all have the grounds. So I guess I should have three screws + a ground if present.


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## joecaption (Nov 20, 2011)

Old switches anyplace may not have grounds but any new ones will and it's code that they do.


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## East_Texas (Nov 20, 2011)

The switch with two wires going to it is pretty much standard in that it controls the power to one light  or outlet, or perhaps two outlets that are wired in parallel for instance lamps on each end of the sofa.  The one with three wires could either be for a three way circuit or again just a switch controlling two outlets like maybe on different walls.   It the wires are all on separate screws then it is most definitely for a three way circuit, if two of the wires are on one screw then it is just a switch controlling multiple outlets.  The most important thing is to replace the switches with switches identical to the ones you remove.  If the switches are old enough they may not have the green screw for ground, but other wise they should have the exact same amount of screws and replacing the wires is as simple as taking one wire at a time off and attaching it to the new switch until all wires are moved.


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## joecaption (Nov 20, 2011)

And there should neve be two wires under one screw. The incoming wires needs a pig tail attacted and only one wire under the screw. The screws are not long enough to be tightened properly with two screws and may strip out if you try it.


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## dtheobald (Nov 22, 2011)

OK, THank you for all of your replies. 

The red wire that is one on post with another black wire actually goes to the other switch next to it. The other switch has a black wire going to it, and this red wire which goes to the switch next to it. That switch has two wires going into it, both black. 

I replaced both switches, and copied the wiring, everything works fine but I am concerned with what some had said. The new switches have green ground screws...currently they are attached to nothing. And one had said to not mount 2 screws on one post...which I did. 

I took photos, but I left my memeory card at home. I can post them tomorrow. I apologize for not responding to my own thread sooner, I dont have the internet at our home, and I was home with a sick baby yesterday, so I missed work-where my internet is.


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## nealtw (Nov 22, 2011)

The 2 wires on one screw should have been wire nutted together with a short third wire to go to the switch.


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## dtheobald (Nov 22, 2011)

nealtw said:


> The 2 wires on one screw should have been wire nutted together with a short third wire to go to the switch.


 
I am not quite sure I understand how to do this. 'nutted together'. In what manner?


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## JoeD (Nov 22, 2011)

Example of a pigtail connection using a wire nut.


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## dtheobald (Nov 22, 2011)

JoeD said:


> Example of a pigtail connection using a wire nut.


 
Perfect! Thanks alot. I did that on my model railroad, and that works fine...Thanks alot!


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