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Thread: Help reconnecting a 4-way switch

  1. #1

    Default Help reconnecting a 4-way switch

    We bought an older house that has a disconnected 4-way circuit. Part of the run has been reconnected to a different 3-way switch that turns on the garage light (both from the back entry door and also inside the garage). This is a rather useless arrangement so I know its not correct.

    The 4-way is supposed to be hooked up to:
    1. Main house back entry door
    2. Garage entry in the Hallway (shown in diagram to left of 3 gang box)
    3. Top of hallway stairs to main living area (shown at top of diagram)
    4. Overhead light in hallway

    I had an electrician come out and he spent over an hour trying to figure out the circuit and could not do it. But I know it has to work ... so I used corel draw and drew a very detailed diagram of where all the wires currently are.

    Would anyone care to help me unravel this mess?

    Thanks in advance! Karen
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  2. #2

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    Don't assume anything in an older house! No telling what is what. Also a previous owner of the house may have told you something which was not quite correct - may have used the wrong terms.

    So first of all, let's be sure we are using the correct terms.

    A "4-way" switch would be used between two "3-way" switches to control say one light.

    Here is a wiring diagram of two 3-way switches with a 4-way switch in the center...
    http://www.electrical-online.com/Fall204.gif

    Examples...
    If you have one light and need two switches, you would use two 3-way switches.

    If you have one light and need three switches, you would use two 3-way switches and a 4-way switch.

    Or if you had one light and need four switches, you would use two 3-way switches and two 4-way switches.

    So just to be clear on what you want...

    Which light do you want these switches to operate?
    How many switches do you want to operate this light?

  3. #3

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    Thanks for the assistance!

    I have one light (over the downstairs entrance hallway) that really needs 3 switches. The first switch is located at the back door. The 2nd switch is located near the inside garage door (to walk in from the garage). The third switch is located upstairs (point of entry into main living area). The only run that has three wires in it (new wiring) is from A to C. All other wiring is old two wire with no ground.

    I know I need a 4-way switch in there somewhere, but there is not one now (I bought one). Somewhere along the line it was removed rendering two switches unusable (see new diagram).

    Also, I would like C to operate the garage overhead light (this makes much more sense).
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    Last edited by karensw; 08-08-2008 at 08:51 AM.

  4. #4
    Moderator & Master Plumber hj's Avatar
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    Default switch

    Your diagram is incomprehensible. It appears that one pair of switches controls only the garage light, and that assumes we are interpreting the hot feed correctly. One three way is "capped off" with a wire nut terminating both travelers. Other lights do not appear to have any switch or hot feed to them. You may just have to isolate the individual wires and identify each of them as to its purpose, and then develop a wiring diagram, including switches, that accomplishes your lighting desires.

  5. #5

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    Quote Originally Posted by hj View Post
    Your diagram is incomprehensible. . .
    Is my diagram incomprehensible or the wiring itself? My diagram is accurate according to what is currently there.

    Yes one pair of switches operates only the garage light. The guy we bought this house from claims to have been an electrician! In any case, the rest of the house is correct and sensible, just this one circuit is a mess.

    I don't mind starting from scratch, I just don't know what can be done with the existing wires that I have in the wall. The only box I can not pull new wire into is the one at the top of the stairs. So any suggestions would be appreciated (I am not an electrician, but I've replaced fixtures and receptacles, etc.). I have some good diagrams on 3 and 4 way wiring but Its still very confusing to me since I don't have three wires to work with (except at the back door to the garage).

  6. #6
    Computer Programmer Bill Arden's Avatar
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    First lets simplify the problem by getting the garage light right.

    back to the first diagram.
    Garage entry in the Hallway (shown in diagram to left of 3 gang box)

    1. In the 3 gang box.
    1.1 Disconnect the upper left wire nut.
    1.2 Disconnect the Bottom left wire nut.
    1.3 Connect the Garage light Black to the white from the 3 way in the single box in the hallway.

    2. Still In the 3 gang box.
    2.1 remove the wire nut connecting the two hots together from the 3 way in the single box in the hallway.
    2.2 Cap one of the Hot's
    2.3 Connect the other hot to the hot supply (black wire on right side of 3 gang box)


    This should make the garage light turn on and off with the switch in the hallway by the garage door.


    Next lets assume the wire that comes into the 3 gang box from the top right is wire from upstairs (upper left wire exit). This would explain why the hall light turns on at all.

    since the hall light also works, we can assume that the "?" in the top drawing is Power for the light

    You need to run a wire to either the hall light or the top switch to make it work right.

    I think it was wired in a somewhat dangerous way in that the upstairs switch switched the black wire to the light between line and neutral and the switch in the box did the same. This would work as long as the switch itself does not get a welded contact and connect line to neural.

    Edit:
    Imagine the light in the middle of two three ways.
    Each three way switches the runner wire to either hot or neutral.

    The light then sees...
    Hot,Hot (off)
    neutral,neutral (off)
    neutral,Hot (on)
    Hot,neutral(on)

    This arrangement is dangerous because if one of contacts in the switch "weld" closed, the switch will then connect Hot to neutral without any load in between. This results in either a dead short or a small plasma arc/fire in the switch.
    Last edited by Bill Arden; 08-08-2008 at 05:29 PM.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  7. #7
    Computer Programmer Bill Arden's Avatar
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    oops. I might have Box A and Box C mixed up.

    Is Box C the three gang box?

    or is Box a the three gang box?
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

  8. #8
    In the Trades Bob NH's Avatar
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    You need to figure this out independent of where the switches and light are physically located. The following description is based on the circuits.

    1. Find the circuit/wire/switch-box where the power (presumably a black wire) is HOT whenever the circuit breaker is on. That is Switch LOCATION 1. A 3-way switch goes in that box and the hot black wire is connected to the common terminal of that switch.

    2. Find the box to which the BLACK WIRE OF THE LIGHT is connected. That is Switch LOCATION 3. A 3-way switch goes in that box and the black wire from the light is connected to the common terminal of that switch.

    3. The pair of wires from the switched (not common) terminals of the 3-way switch in Switch Location 1 and the pair of wires from the common terminals of the switch in Switch Location 3 should both go to the same box. That is Switch Location 2. The 4-way switch goes in that box.

    4. The pair of wires from Switch Location 1 are connected to a pair of terminals on the 4-way switch that are never connected to each other regardless of switch position (when no wires are connected to the switch). Use your multimeter to check if the terminals are not labeled. The pair of wires from Switch Location 3 are connected to the other two terminals of the 4-way switch.

    5. The white wire connected to the light fixture should find its way back to Switch Location 1 and be connected to the neutral at that box. It should pass through the other boxes without being connected to any switches.

    There may be other possibilities but if you can understand the above you should be able to figure it out.

  9. #9

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    I identified one of the unknown wires, it definately goes up to the switch at the top of the stairs. But it only has 2 wires in it. I can not seem to trace the other unknown wire (the one that was cut). I also can not figure out where the other wires in the upstairs box go.

    But since we are rennovating this house we have another option. The garage (where the three gang box is) as well as the spare bathroom up the hall has no sheetrock yet. We studied this from so many different angles and I *think I have the best solution.

    We did figure out a way to pull one 3-wire into the upstairs box. It would not take exactly the same path as the old wire, but it would go over the bathroom ceiling and end up in the same place (but i would be pulling the old wire out of the box to pull the new wire in).

    Also it would be no problem to pull two three-wire runs from the garage to the hall ceiling light fixture.

    Then I could feed the circuit from the panel straight to the light fixture and then out to the switches. One of the runs out of the fixture would go to the back door 3-way switch, the other would go to a 4-way at the garage door entry, then on up to the 3-way at the top of the stairs. I found a diagram of how to do this in a book and it sounds like it might work.

    I have labeled and disconnected all the wires in the garage and will be starting from scratch. I just need to know how to hook up the garage light into this new scenario.

    Also, I'm not sure what the other wires in the upstairs box were being used for. I was thinking about leaving them disconnected, then turning the breaker on and seeing what was not getting power (I think its a couple of outlets in the laundryroom).

    Does this sound like the best way to go?
    Last edited by karensw; 08-08-2008 at 10:58 PM.

  10. #10

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    Quote Originally Posted by Bill Arden View Post
    oops. I might have Box A and Box C mixed up.

    Is Box C the three gang box?

    or is Box a the three gang box?
    Box C is the three gang box (only has one switch in it though).

  11. #11

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    Quote Originally Posted by Bill Arden View Post
    Next lets assume the wire that comes into the 3 gang box from the top right is wire from upstairs (upper left wire exit). This would explain why the hall light turns on at all.

    since the hall light also works, we can assume that the "?" in the top drawing is Power for the light
    Ok I didn't understand this when I first read it ...

    But the hall light did NOT work at all before I disassembled everything (just the garage light did). But yes, the wire that comes into the 3 gang box is the wire from the upper left wire exit upstairs, I've confirmed that. So you think the hall light was supposed to get power from the upstairs box? I never thought of that (I'm just a DIY'er)

  12. #12

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    Quote Originally Posted by karensw View Post
    ...I just need to know how to hook up the garage light into this new scenario...
    All these switches can control *one* light or *two* lights.

    If connected to one light, every switch will control that light only.

    If connected to two lights, every switch will turn both lights on at the same time and off at the same time.

    In other words, with say 3 switches, you can't have 2 switches control the hallway light and the 3rd switch control the hallway *and* the garage light.

    It is either or! Either *all* switches control the hallway light only. Or all switches control both the hallway and garage light.

    Or install a separate switch for the garage light.

  13. #13

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    Yes I do understand that. I don't wish to put the garage light on the same switches. The garage fixture is fed and switched in the garage directly behind one of the three way switches, the one by the garage door.

    But I'm thinking I could simply feed this switch first from the panel, then go on to the hallway light fixture to make the 4-way switch circuit.

    Thanks!

  14. #14
    Moderator & Master Plumber hj's Avatar
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    Default switch

    It is still confusing, but the simplest way to describe it is that the 4 way switch is installed between the two three way switches and either needs two wires in and two wires out, or four wires if the wire is going back to a three way switch. The power goes into one three way switch, and the light(s) is connected to the second three way switch.

  15. #15

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    Ok here is the new scenario...

    I have managed to pull a new 3 wire cable between B and D.
    I already have a 3 wire cable between A and B
    I am pulling two new 3 wire cables (along with the current 2 wire cable) from B to the hall fixture. This is the easiest fixture to pull several wires to, that is why I chose to do it this way.

    With this arrangement I can feed box C first (for the garage light). Then feed the hallway fixture with 2 wire cable. Then come back to B with one of the 3 wire cables (and a 4 way switch), and then connect up to D (3 way switch). Using the other 3 way cable from the hall fixture I can hook up a 3 way switch to A. I have a diagram from a book on how to hook up the wires so I think it should work.

    Previously there was only a 2 wire cable between A and B, plus 2 other wires that I'm not sure about. I had to use the 2 wire cable to pull the 3 wire cable into the box, so I no longer have it.

    The hallway light was not working at all when I began, but now I am not sure if power was coming from one of the wires in box D (feeding the hallway light), or exiting the box (feeding two other recepticals on the circuit). I guess I will just have to test it when I turn the breaker back on. If power was feeding the other two recepticals, will I need to pull another 2 wire cable into the box (possible but very difficult) or can I tap into the three way switch?

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