3-Way Light Switches

Discussion in 'General Electronics Chat' started by Ehesner, Jan 6, 2016.

  1. Ehesner

    Thread Starter New Member

    Oct 25, 2015
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    I realize there are 3 or 4 different ways of wiring 3-way switches, depending on where the power comes in, but can someone tell me an easy way to temporarily disable one of two 3-way light switches in a room without impacting the operation of the other switch?
    Ed
     
  2. marcf

    Member

    Dec 29, 2014
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    Yes there is a way to do this, but I am not sure if this subject is ok for the forum. If it is, the answer is pretty easy.
     
  3. Brownout

    Well-Known Member

    Jan 10, 2012
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    It's OK.
     
  4. #12

    Expert

    Nov 30, 2010
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    Enough information?
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Which country are you in? In the UK, the circuit in post #4 would be called a 2-way circuit.
     
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  6. MaxHeadRoom

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    Jul 18, 2013
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  7. #12

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    The regulars know I am self-taught, so they know I can't quote The Gospel of nearly anything, unless I'm quoting a book, in quotation marks. I called that a 3 way switch because that's what it says on the box when you buy the SPDT switch. I don't know whether I called it the wrong thing or that terminology is just peculiar to where I live.
     
  8. Brownout

    Well-Known Member

    Jan 10, 2012
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    It's what we call it in the US. We can go through all kinds of machinations defending each of our terms, or just agree to disagree and try to work out the communication.
     
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  9. #12

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    That's good enough for me. I also don't argue about "color" vs "colour". I've had some experience in 6 languages, 7 if you count British.:D Eight if you count the myriad abbreviations and abysmal spelling on the Internet.:rolleyes: Call it however many ways you want. The schematic is the true language of electronics, so it trumps verbal communication.
     
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  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I agree. Unfortunately the TS hasn't provided one, or a clue to his location, so we don't know whether his interpretation of '3-way' is the US or UK one.
     
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  11. ShopRat59

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    Nov 27, 2013
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    Based on the wording - two switches to control a single light, that sounds like US to me. Assuming that, we are talking about a SPDT switch that has two brass screws for the "travelers" and one black "common" screw. There are actually 6 ways for this configuration to be wired based on the order of the switches and light and which box the line (power) enters:

    1) line/switch, switch, light
    2) switch, line/switch, light
    3) switch, switch, line/light
    4) line/switch, light, switch
    5) switch, line/light, switch
    6) switch, light, line/switch

    #12's answer is for configuration #1 and assumes you want to bypass the first switch. You need to get out your voltage tester, determine which box the line is in, then turn off the power and use a continuity tester to determine the order the boxes are wired. Return with that informaton and specify which switch you want to bypass - then you can get a safe answer. Also, even though you say it is temporary, a better solution would be to remove both switches, rewire the box you want to bypass and put a blank cover on it and then put a SPST (normal) switch in the other box.

    Regardless, I still think we need a moderator to say it's ok to answer this question since it is about line voltage.
     
    Last edited: Jan 7, 2016
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  12. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    FWIW: Of course I'm not a moderator -- howbeit, as I understand the bylaws, the restriction upon discussion of mains connected circuitry applies to non-isolated power conversion schemes... Mains wiring and mains operated equipment are frequently discussed sans censure...

    Best regards
    HP:)
     
  13. crutschow

    Expert

    Mar 14, 2008
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    So it sound like you want to:
    1. Open the breaker to the switch power (test the light to be sure the circuit's dead).
    2. Remove the two wires to be tied together, as shown by #12 in post #4, from the switch and use a wire-nut to tie the two wires together .
    3. Close the breaker to reapply power.
    4. Test switch.
     
  14. ShopRat59

    Member

    Nov 27, 2013
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    OK good enough for me, still need the info from OP, again #12's solution is perfect for that specific 3-way set up, but I do not believe it works for all setups.
     
  15. #12

    Expert

    Nov 30, 2010
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    I guess that's one of my personal problems. I think at the concept level (mostly to avoid doing real work, like math) and I'm so accustomed to working upside down, backwards, and left handed that I don't think about six different ways to arrange the parts (that will work). I just flop the concept on the table and when the measurements say the true configuration is shaped differently, I adapt, and I expect everybody else to!

    My bad?
     
    Last edited: Jan 6, 2016
  16. Ehesner

    Thread Starter New Member

    Oct 25, 2015
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    Sorry, I guess I should have been more specific. I'm in the U.S. A 3-way switch here means one (or more) lights (or receptacles for that matter) operated from two different switch locations. My two light switches are in a bedroom. There is a combination ceiling light/ceiling fan in the center of the ceiling. The 1st switch near the bedroom door is in a double box and also has a switch for the fan, but I'm not concerned about the fan. The 2nd light switch is on the opposite side of the room. I'm making the rash assumption that the power comes into the box near the door and runs from that switch to the ceiling light then from the light to the 2nd switch. My reason for "temporarily" disabling the 2nd switch is that we have a 2-year-old who's crib is now within an arm's reach of the switch, and we don't want him turning the light on and off continually, so I just want to disable the switch until either his bed is moved or until he's a bit older and doesn't care about messing with the light switches, and then I'll hook it back up.
     
  17. Tesla23

    Active Member

    May 10, 2009
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    https://www.google.com.au/search?q=baby+proof+light+switch+cover&biw=1590&source=lnms&tbm=isch
     
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  18. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Your three way switch simply has a shuttle and two conductors to connect the bulb. Same is on each switch. You will see the shuttle the two conductors. You will see the unique shuttle wire when you remove the outlet cover and the switch. Then use two wire nuts (one to connect the shuttle wire to a conductor, the other to cap the bare conductor). The only impact of which conductor to connect the shuttle wire to will be whether the other switch is up vs down for the off position.

    See #12's drawing above. Leave the switch out of the box and buy a switch cover with no opening.
     
  19. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Ok, never mind what I wrote above, this is the safest (for you) and easiest (for you) solution. Hopefully your finger and your significant other's finger are long enough to reach the switch.

    image.jpg
     
  20. marcf

    Member

    Dec 29, 2014
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    I guess a picture is worth a few words.

    Also has any one seen this 'truth' table before?
     
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