Could someone please un-baffle me?

Reply

  #1  
Old 12-22-14, 05:39 PM
Member
Thread Starter
Join Date: Apr 2010
Location: USA
Posts: 375
Could someone please un-baffle me?

Ok - for whatever reason, 3-way circuits blow my mind. It's like juggling - I can juggle two balls but toss in a third and I shut down.

Situation: Replace a single pole light switch with a 3 way switch(because that's all I had) in single pole mode.

I took the old switch out to find 3 black wires. Looks like this is some sort of 3 way circuit even though it's just a single pole switch. There is one wire on the top screw and two wires at the bottom screw. So, I duplicate this wiring using my 3 ways switch and the lights don't work. By fiddling around, I discover that if I put one wire per screw terminal on the 3 way switch, the lights work! So I install the switch and put the cover plate on.

Fast Forward 2 days----->
My outside light no longer works. I discover that it only works if my new kitchen light switch is off.

Since my brain is obviously not sophisticated enough to comprehend what is happening, would someone mind throwing me a rope? (and maybe a drawing too?)

Thanks!
 
Sponsored Links
  #2  
Old 12-22-14, 06:16 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
Why not pop the 59 cents for the proper switch. Unless you had a 3 way setup, the 3way switch isn't what you need.
 
  #3  
Old 12-22-14, 06:21 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,494
What you are looking at is improper wiring. Sloppy wiring. As an electrician we only put one wire on one terminal. So that means on my standard single pole switch you'll only find two wires.

Many people will add on to a box and rather than connecting two wires together with a short piece as a tail.... they'll look at the switch and see two wires, locate the hot one and then use the back stab terminal or the side screw if the device was originally wired as back stabs.

So with your three black wires..... those two were on the same terminal. Those two need to be combined together again with a single tail.

You can use a three way switch to replace a single pole. You use the common/dark screw and one traveler screw. You will need to rotate switch so that the light is on when switch is up.
 

Last edited by PJmax; 12-22-14 at 06:36 PM.
  #4  
Old 12-22-14, 06:22 PM
Member
Thread Starter
Join Date: Apr 2010
Location: USA
Posts: 375
Point taken. But still, the question stands.
 
  #5  
Old 12-22-14, 06:22 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,361
What you had was power in and power out to another part of the circuit on one end and the switched hot out on the single wire.

Only one wire should have been under the screw. A pigtail should have been used instead.
 
  #6  
Old 12-22-14, 06:46 PM
Handyone's Avatar
Forum Topic Moderator
Join Date: Aug 2000
Location: U.S.
Posts: 5,451
I think you are wondering why both inside and outside lights would not work when you wired the 3-way switch.

First, the wires on the 3-way were placed randomly, and in no way followed any of the rules of wiring.
So in that sense you got lucky and the interior light worked when switch was thrown.

The outside light works when inside light is off because the 3-way switch is sending hot to what is supposed to be another 3-way switch, Not a light. You need to abandon the 3-way switch.
 
  #7  
Old 12-22-14, 07:02 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,494
A standard wall switch is a SPST (single pole single throw)
A three way switch is a SPDT (single pole double throw)

It will replace a standard wall switch but there is no marked UP position.
Once the OP combines his hot feed in and hot feed out back together.... his switch will work correctly.
 
  #8  
Old 12-22-14, 07:13 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,662
This is basically the guts of a 3-way switch.

Name:  GrayBg.jpg
Views: 204
Size:  13.0 KB
 
  #9  
Old 12-22-14, 07:15 PM
Handyone's Avatar
Forum Topic Moderator
Join Date: Aug 2000
Location: U.S.
Posts: 5,451
I know. OP wanted to know why the way he wired the 3-way would cause the interior light to work and exterior light to work only when interior light is in Off position.

My post was an attempt to explain that. You, Pete, would be better at explaining
 
  #10  
Old 12-23-14, 03:49 AM
Member
Join Date: Mar 2010
Location: USA
Posts: 2,857
Explanation only.

Why the OP's wiring resulted in the exterior light working only when the interior light was in the off position.

The wire continuing to the exterior light was randomly connected to a terminal (a side terminal or traveler terminal or non-dark terminal) of the new 3 way switch that is live only when the switch is in the position that does not serve the interior light.

The wire continuing to the exterior light used to be connected to be always live as needed, sharing the screw of the incoming live power. (A switch further downstream controlled the exterior light.)

***********

The original switch had two terminals. You did not want to split the three wires onto three different screws in this case.

* When two or more wires want to go under one screw, cut a short length (pigtail) and connect that to the screw. Connect the other end of the pigtail to the other wires in question using a wire nut.
 

Last edited by AllanJ; 12-23-14 at 04:27 AM.
  #11  
Old 12-24-14, 12:57 PM
Member
Thread Starter
Join Date: Apr 2010
Location: USA
Posts: 375
Ok - thank you all.

I can just get a single switch - no problem. It's just that I had a 3 way handy and I thought that you *could* use a 3way in place of a 2 way if you needed to - this has been confirmed. I probably just connected the wrong wires - or - had a temporary loss of my mind and arbitrarily connected the 3 black wires to one screw each.

My main point was to confirm that you *can* use a three way in place of a two way if need be. In this case, I will buy a two way and use a pigtail. My wife has since pointed out that one of our receptacles in another room now only works if the kitchen light is off.

Thanks for the info guys! Have a Merry Christmas!
 
  #12  
Old 12-24-14, 01:07 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,361
Changing to a single pole switch and adding a pigtail should solve your issues.
 
  #13  
Old 12-25-14, 10:12 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,984
There is no such thing as a two way switch. They are single pole and three way (among others).

Yes, you can use a three way in place of a single pole switch. You will only use two of the screws, the common, and one traveler screw. Otherwise wiring will be the same as it was with the single pole switch. The three way is not marked "On" and "Off" so switch should be installed so the light is on when the three way is in the up position.
 
  #14  
Old 12-25-14, 10:53 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,662
Technically a 3-pole switch is a single pole also but often a switch for controlling lights from only one location is called a single pole to differentiate it from a 3-way.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'