3-way switch controlling multiple fixtures

Discussion in 'Shop Talk' started by greg273, Sep 18, 2006.

  1. greg273

    greg273 Well-Known Member

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    Can anyone explain how to wire two lights controlled by 3-way switches? Power is running through the first switch, ,then to the fixtures, then to the other 3 way. All the diagrams I've found are very hard to follow! I've wired the rest of my place with no problems,however this circuit has got me all sorts of confused! thanks!
     
  2. morrowsmowers

    morrowsmowers Well-Known Member

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    The hot leg should be going directly to the fixture. The neutral should feed to the first switch which will have 2 more wires going to the second switch and then another single going from that switch to the fixture. This allows either switch to control the fixture. The 2 wires running between the 2 three way switches are called 'travelers'. What you will probably see is three wires running from one switch to the fixture, three wires running from the other switch to the fixture, and the power feeding in also coming into the box where the fixture is mounted. All of the wiring will need to be sorted out in that one box. However, it is also possible that power is feeding into the first switch, running over to the next switch, and finally to the fixture. In that case you will have 3 wires (1 white, 1 black, 1 red) and a ground running between the switches. Some electricians make this even more confusing by not using color coded wires - they just mark them with electrical tape bands so they know which is which.

    Ken in Glassboro, NJ :)
     

  3. tiogacounty

    tiogacounty Well-Known Member

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    Sorry, this is wrong. You never switch a neutral, only hots. Also there is no confusion about color coded wires. The vast majority of three wire switches the average homeowner comes it contact with are wired in NM cable (Romex) and there are no color options, so the proper technique is to mark them with electrical tape.
    To properly wire this set up with romex lets walk through the circuit from the panel. Start with a two wire romex fed from the panel. This gives you a 120 volt hot (black wire) and a white neutral. I have ignored the ground wire for this example. This wire goes from the panel to the first switch box. There is also three wire romex run from the first switch box to the second switch box. In the first switch box the white wires are spliced together with a wire nut. The black wire coming from the panel is attached to the dark colored screw on the switch. The red and black wires from the three wire are attached to the two brass screws, these are your travelers. At the second switch box you will need the other end of the three wire romex and a two wire romex to run to the lights. You wire this switch exactly the same. The travelers go on the bright brass screws. The black from the two wire romex goes on the dark colored screw. the whites are spliced together. From here you run the two wire romex to the lights. If you have more than one light, run a two wire romex from box to box and splice everything color to color. This is the simplest way to do the job, but certainly not the only way. good luck.
     
  4. Stillponds

    Stillponds Active Member

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    One of the screws on the three way switch will be a different shade or color than the other two screws, this is the common screw. Land a hot wire on that screw on one of the switches. On the other switch from the common screw run a wire to both of your lights, this is your switch leg. Run a neutral wire to both of your lights. Run two wires between the switches from the other two screws and you are done.
     
  5. morrowsmowers

    morrowsmowers Well-Known Member

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    Ooops, how did that neutral slip in there! Of course the neutral should be directly connected through the entire circuit with the hots being switched. Concerning the color of the wires around here we use 3 conductor Romex which has a bare ground, a white, a black, and a red wire in it. Only see the tape on the wires in the really old houses with knob and tube wiring it 'em. Also, around here the Romex now comes with its outer jacket in lots of pretty colors which tell the inspector exactly what wire it is. Plain old white is no longer in fashion.

    Ken in Glassboro, NJ :shrug:
     
  6. The Paw

    The Paw Well-Known Member

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    About 8 years I re-wired my whole house using a do-it-yourself book. No problem until I got to the damn 3 way switches. I wanted a single switch at the bottom of the stairs that controlled the light in a ceiling fan, as well as a bulb further down the hall. I wanted the second switch box to also control the lights, and to have a separate switch for the fan.

    The book had diagrams of a 3 way switch, but I have to tell you I practically broke down in tears trying to get my schematic right (big manly tears :Bawling: ...). It took two days to do it, because I had to keep walking away to do something else, or I would have kicked it all to bits...

    Eventually it got done and passed inspection, but I doubt if I could do it again, much less write it out in paragraph form. my advice is to print out tioga's reply, buy some pencil crayons, and start drawing.

    Good luck,
     
  7. tiogacounty

    tiogacounty Well-Known Member

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    If it's makes you feel better. I have seen a few of my fellow electricians, with decades of experience, that were stumped trying to troubleshoot an existing three way in an old office building. It worked, but it took ever ounce of brain we had to figure out what was what, and why it worked. Like I said there is more than one way to wire them and it can get real confusing, no matter how much experience you have.
     
  8. agmantoo

    agmantoo agmantoo Supporter

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  9. rambler

    rambler Well-Known Member Supporter

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    When the electrician's rewired my 1926 farmehouse fusebox over to a breaker last summer, they got everything right, all looked good. Went home. Over night, the one set of 3-way switches was odd - the 2 lights on it glowed. Not 'on' but just glowing, couldn't see it in daylight but at nite....

    Told them about it the next day. He says, 'Oh you have one of those old style 3-ways, often can't figure them out. Brings us to tears. But we just swap the hot & neutral, and then they work.'

    It worked. I decided not to ask any farther..... ;)

    --->Paul
     
  10. greg273

    greg273 Well-Known Member

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    You guys are great. Actually I found a good drawing, thanks to a friend who is a genius at searching the web. ( it helps to have a high speed connection, too)....if I can figure out how to upload it, I will...


    basically the two fixtures are connected using TWO 2-wire romex cables....

    this one had me stumped!! yes, I am basically following the book...carefully, and slowly.... ONE or TWO circuits per day, max! (only a few more to go!)
     
  11. tiogacounty

    tiogacounty Well-Known Member

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    If you are saying that the potential exists for the hot wire of a circuit to be traveling in a different Romex from the neutral, you have to correct it. This would be the case if somebody ran TWO 2-wire romexes between the three ways instead of a three wire. A neutral that is physically seperated from it's hot wire can get hot, very hot. Good luck.
     
  12. greg273

    greg273 Well-Known Member

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