Light switch and light connection help

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  #1  
Old 08-26-13, 02:44 AM
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Light switch and light connection help

Attached is a diagram of what I now have wired in my bathroom. I took down the old porcelin light fixture to see how it was wired and when I put it back up the screw cracked the hole opening, so it can no longer be used.

I want to put up a temporary light, so that I can finish renovating the bathroom. I'm not sure how to proceed. The temp light fixture has black, white and ground.

I'm ass-u-m(e)ing (don't make an as* out of u and me), which I rarely do and is why I'm here, that I should hook it up as follows:

- The white wire from the power comming in, should be hooked up to the new temporary fixtures black wire.

- The white wire from the switch, should be hooked up to the new temporary fixtures white wire.

- The black wire from the power comming in should be hooked up to the black wire from the switch.

- At the switch the white wire should be connected to the brass terminal on the top right hand side

- And at the switch the black wire should be connected to the silver terminal on the bottom right hand side

Is this correct or am I way off base.

Any help would be appreciated. (BTW, I do better with pics than words, when it comes to this stuff)

Cheers,
Fran
 
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  #2  
Old 08-26-13, 03:09 AM
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Welcome to the forums.

You're almost correct,

The white (neutral) wire coming in to the box goes to the white of the light. (silver screw)

The black (hot) wire coming in should go to the white wire going to the switch. That white should be re-marked another color like red or blue so that it's not confused as a neutral.

The black wire coming back up from the switch goes to the black of the fixture. (brass screw)

If that is a standard single pole switch that you are using......both screws should be the same color as there is no difference between them.

If your switch has two silver screws and a brass screw.....that's a three way switch and shouldn't be used there.
 
  #3  
Old 08-26-13, 06:07 PM
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Thanks for the welcome and quick response.

So, If I understand you correctly the new wiring diagram I've attached should be correct.

The switch that is in currently has 2 brass screws, top right and left and a extremely tarnished silver screw...or black screw, bottom left (when facing the switch).

Do I need to replace the switch??.. with a standard single pole switch?? Also, what amp and voltage ratings should my switch have?

Why did the way it was hooked up work correctly for the last 30+ years if it was done wrong.

I don't know what other outlets are on the other side of the power feed to the light. Does that make any difference to what type of switch is used? Hope that wasn't a stupid question.

Thanks in advance,
Fran
 
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Old 08-26-13, 07:07 PM
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Yes except the white of the switch loop has not been remarked as an ungrounded conductor. Usual colors are red or black but it may be remarked any color but green or gray. You can remark it with a band of colored tape on each end or a felt tip marker or colored liquid electrical insulation.

P.S. I like your diagram. Good job.
 
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Old 08-26-13, 07:12 PM
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So, If I understand you correctly the new wiring diagram I've attached should be correct.
Almost. The white wire going to the switch needs to be tagged with electrical tape or permanent marker at each end to show that it is carrying ungrounded current. You don't need that piece of red wire at the switch. The power coming in should go to the common (black) terminal on a 3-way switch.

The switch that is in currently has 2 brass screws, top right and left and a extremely tarnished silver screw...or black screw, bottom left (when facing the switch).
Yes. That's a 3-way switch.

Do I need to replace the switch??.. with a standard single pole switch?? Also, what amp and voltage ratings should my switch have?
I would replace it with a single-pole single-throw switch - an on/off switch - but you don't absolutely have to. It's just a waste of a more expensive device to leave it there. Any inexpensive on/off switch is good enough for this.

NOTE: A 3-way switch is a single-pole double-throw switch.

Why did the way it was hooked up work correctly for the last 30+ years if it was done wrong.
IDK. I also don't know how it was wired before.

I don't know what other outlets are on the other side of the power feed to the light.
Well, you know more about that than we do. Why are you considering this?
 

Last edited by Nashkat1; 08-26-13 at 09:25 PM.
  #6  
Old 08-26-13, 08:01 PM
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Will mark the white of the switch loop.

Ray, thanks about the diagram. Photoshop is great for quick renderings like this.
 
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Old 08-26-13, 08:15 PM
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Nashkat1

I used the piece of red wire as my marker. The existing wire was brittle and broke off when I pulled it out to have a look. It was then too short to reach the switch terminal. I'll be replacing the wire from the switch to the fixture.

You say the power coming in should go to the common (black) terminal. So, I should reverse the wires on the switch? because the black screw is on the bottom left (when facing switch).

How it was originally wired is exactly how it's shown in my first post. Except the black wires were taped together, no wire nut.
 
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Old 08-26-13, 09:29 PM
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I should reverse the wires on the switch? because the black screw is on the bottom left (when facing switch).
If you're going to keep that switch, yes. I would replace the switch with a SPST switch from the 59 cent bin.
 
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Old 08-26-13, 10:42 PM
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Thank you Nashkat. I will replace the switch but please excuse my ignorance, what is a "SPST switch" ? Also, what amp and voltage ratings should my switch have?

And remember, I'm in Canada, only thing you can get here for 59 cents is 38 cents Never even heard of a 59 cent bin.

Any thoughts as to why the original wiring worked (see first post pic).... just curious. I am new to all this.

Fran
 
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Old 08-26-13, 10:52 PM
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SinglePoleSingleThrow switch. A regular light switch with two brass screws and a green ground screw.
 
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Old 08-26-13, 11:15 PM
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Ray, thanks for the aka of SPST.

Does it matter which wire is connected to which terminal on the "SPST switch"?

Should I be concerned with amp and voltage ratings of the new switch?
 
  #12  
Old 08-26-13, 11:25 PM
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No, the terminals are interchangeable. If it is sold as a light switch it will handle the load, usually rated 15 amps.
 
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Old 08-26-13, 11:28 PM
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Amp and voltage ratings of the new switch? A concern??

Whoops, That last part of your post wasn't there when I submitted this.
 
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Old 08-26-13, 11:31 PM
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No, as stated in post #12.
 
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Old 08-26-13, 11:35 PM
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Thank you Ray,

Just out of curiosity, do you know why the way the wiring was done originally worked and didn't cause any problems?
 
  #16  
Old 08-27-13, 12:21 AM
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Your original 3-way (spdt) switch would switch the power from the black screw to either of the brass screws. Since one of the brass screws was not connected to anything the electrical circuit was not "closed" or to put it another way, the electricity had nowhere to go when the switch position selected the unused screw.

Another way to think of it is driving down a street and coming to a T intersection where you have to turn either left or right. Turning right goes to the lamp and turning left goes to a dead end.
 
  #17  
Old 08-27-13, 12:27 AM
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Thanks Furd,

I think I understand what you posted. I'll read that again in the morning, when I'm not so tired.

Fran
 
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Old 08-27-13, 08:10 AM
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Ok that all worked, thank you very much everyone.

But now we want to add a second light between the first light and the switch that will turn on and off, by the switch, with the first light.

How do I wire that?
 
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Old 08-27-13, 10:30 AM
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Is this what you mean?
 
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Old 08-27-13, 10:42 AM
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But now we want to add a second light between the first light and the switch that will turn on and off, by the switch, with the first light.

How do I wire that?
You can't connect a load to the two wires between the existing light and switch because you don't have a complete circuit there. There is no neutral.

As Ray's diagram shows, you can add additional lights controlled by this switch by wiring from the connections for the first light fixture.
 
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Old 08-27-13, 11:04 AM
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Running a new 2-conductor cable to the new light is the simplest. The other way is to replace the existing cable with a three conductor cable. It is extra unneeded work in your case.
 
  #22  
Old 08-28-13, 07:44 PM
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Thank you all very much for your input and direction, it was extremely helpful.

Cheers,
Fran
 
  #23  
Old 08-29-13, 02:43 AM
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That's how we get paid here, by people coming back to say thank you.

You are quite welcome!
 
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