single pole one a 3-way

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  #1  
Old 08-07-06, 10:39 AM
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single pole one a 3-way

Is it common to use a single pole switch in conjunction with double pole switch in a 3-way installation?

I have one this way. Power runs to the double via 2 wire cable, then runs to the single pole via a 3 wire cable, and then to the lights via 2 wire. I suppose someone did it to save a buck.

Also, is it common/acceptable to not attach the ground wires to the ground screw of the switch, but attach them to each other? I have several like this.
 
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  #2  
Old 08-07-06, 10:59 AM
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If you have two way switch and one three way switch, then you cannot control the light completely from both locations. No, this is not common. If what you say is correct, then I suspect someone had no idea what they were doing when they replaced one of the three way switches.

However, do not jump to conclusions. Sometimes people combine a three way switch and a two way switch for a specific reason. For example, I have just such a setup in y bathroom. The arrangement of the wiring powers the night light bulb and the regular bulb in my ceiling light, but prevents both from being on at the same time.

The devil is in the details. Just what did they do with the two traveler wires at the two way switch?

In earlier editions of the NEC, it was not required to ground switches. In fact, at one point switches were not made with ground connections. Switches installed when no ground was required may not be grounded, and are not a code violation. I would, however, ground them if came across such a situation where a ground wire existed in the box.
 

Last edited by racraft; 08-07-06 at 11:23 AM.
  #3  
Old 08-07-06, 12:31 PM
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Thanks for the reply. Here's my situation, this switch worked fine until I unscrewed it and pulled it out from the box to look at the wiring. When I did that, the red wire came loose (it was in a hole, not wrapped on a screw) I am not sure which hole it was in though. I'll try to describe how it is wired other than that.

Power feeds from main panel to double pole switch on 2 wire cable, where a 3 wire cable is present. Grounds connected together, whites connected together. Black from 2wire stuck in hole on lower left (referenced from looking at back of switch). Black from 3wire connected to upper left screw. Red wire was?

At the single pole, the 3 wire comes in and another 2wire goes out to light. Grounds connected together, whites connected together. Black from 3wire goes in lower left hole. Red from 3wire goes in lower right hole. Black from 2wire goes in hole in upper right.

I made the mistake of not looking at what the holes on the back of the switch are labeled.

I am thinking I may be easier just to go buy a double pole and connect everything in the standard manner (and take all the wires out of those holes and put on the screws!)
 
  #4  
Old 08-07-06, 12:36 PM
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if you choose to not connect any ground wires to the switch (but if they are available, it is not a bad idea) but please use a plastic wall plate
 
  #5  
Old 08-07-06, 12:40 PM
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You should not use the back stab connections. As you have discovered, they are unreliable. When you find a switch or receptacles wired using them, you should rewire it using the screw terminals.

The location of the terminals on a three wire switch means nothing. Terms like upper left, lower right, etc are meaningless. Different manufacturers put the connections in different locations.

This does not sound like a two way switch and a three way switch. It sounds like two three way switches.

How many screw terminals (not counting any ground screw) do the switches have? If you cannot identify the common and traveler terminals by the screw color, then simply go and buy a new switch.
 
  #6  
Old 08-07-06, 01:16 PM
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The switch which I assumed to be a single pole has two screws plus the ground screw. The black wire that goes to the light is stuck in a hole near the corner where the ground screw is located.
I think I will just go buy a double pole switch and be done with it.
 
  #7  
Old 08-07-06, 01:20 PM
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Are you sure that what you suspect is a ground screw is really a ground screw?

I agree, throw these switches away and buy new three way switches. Wire them properly. The common terminal will be a different color from the two travelers. The ground screw will be green.
 
  #8  
Old 08-09-06, 06:52 AM
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racraft, you were correct. I got a chance to pull out the switch and look at it. The switch which I thought was a single pole is actually a 3-way with no ground screw. Apparently another back stab connection was my problem, as when I pulled the switch the wire in the common hole just slid out. I reconnected everything to screws and it works fine.
 
  #9  
Old 08-09-06, 07:00 AM
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I'm glad you solved your problem.

Just a couple of comments:

Switches made some years ago do not have ground screws. Back when most circuits were not required to be grounded, there would be no need for a ground screw.

Back stab connections are notorious for failing. Whenever I come across one while working on a circuit, I correct it. This is not always easy to do, as sometimes the wires are short and I sometimes have to add a wire nut and pigtail, but I know that the connection to the screw terminal is much better and much less prone to failure.
 
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