Stumped by 3 way switching

Discussion in 'Electrical Forum discussion & Blog' started by Stephie, Jul 10, 2009.

  1. Stephie

    Stephie New Member

    Messages:
    5
    Location:
    Australia
    I have a new light fitting with live,neutral, earth
    but the feed has live,neutral,earth,and a switch wire.
    Where do I connect the switch wire?
    Last edited: Jul 10, 2009
  2. nickdel

    nickdel New Member

    Messages:
    32
    Please be more descriptive. What is in the electrical box you are wiring the fixture to? How many cables come into this box? What are the colors of the wires that come out of the cable(s)? How did this fixture work before? How many switches controlled the previous fixture?
  3. Stephie

    Stephie New Member

    Messages:
    5
    Location:
    Australia
    This fitting is in my lounge room and it did previously work via my old fitting. That fitting had 4 termination points for these wires.
    My current fitting has only 3 temination points. Earth, Active and Netural.
    The wires are 2 Earth (Green/Yellow), 2 Active (Red), 2 Netural (Black) and 1 Switch wire (Red with white sheath).
    This is the only light in my apartment which worked off two switches located at either end of the room.
    The cables run back to a 10a 240-415v breaker on my local switchboard located in my front entry.
    This is all copper wiring.

    Configuration for the old fitting was Active was in loop termination and switch wire and netural either side.
    Last edited: Jul 10, 2009
  4. nickdel

    nickdel New Member

    Messages:
    32
    My apologies, I neglected to see that you were in Australia when I read your first post. I do not know Australian electrical code, nor do I know the nomenclature. I can tell you how a 3-way switching system works, and perhaps you could use that information to figure out what you need to do.

    A 3-way switch has two positions, call them A and B. Note that these positions are NOT on and off, just A and B. A and B are two different paths for the electricity to flow. Either A or B will allow the electricity to flow, but both switches must be in the same position for this to happen. Changing either switch will open the circuit and stop current flow.

    A 3-way switch has three terminals. One is called the common and the other two are called travelers. When power comes into the first switch, it is connected to the common terminal. Then one wire is connected to each of the traveler terminals and leaves the switch box. They go directly to the second 3-way switch. They can stop inside other boxes and be spliced if necessary, but they cannot be interrupted. They must go from one switch to the other. When they get to the second 3-way, they go on the traveler terminals of that switch. Then a wire is connected to the common of the second 3-way switch, and this wire goes to the light fixture. This is called the switch leg. Out of the light fixture comes the neutral, and this goes back to the panel.

    When you took the old fixture down, how did the wires look inside the box? Were there splices? For example, were the two neutral wires spliced with a third shor piece of neutral wire that went onto the terminal of the fixture? Was this the case with the ground and or/hot (active)? Is this a double pole breaker? Again, I apologize but I'm still having difficulty picturing what you have in your home. Perhaps a trip to your local home store might be in order. Do they give advice and answer questions in those stores?
  5. Thatguy

    Thatguy Homeowner

    Messages:
    1,460
    Location:
    MD
    Scroll down in this link to the 3-way diagrams.
    http://en.wikipedia.org/wiki/Switch
    There are several possible schematics (an abstract representation), and many more wiring diagrams (a literal implementation).

    It's not so obvious, but for a single SPST switch or a 3-way switch arrangement,

    the switch or the "composite switch",
    and the source,
    and the load

    are all in series.

    This is all just to make it work.
    If you also want safety, there needs to be a ground in there somewhere. That's where the elec. codes come in.

    While testing, to avoid being fooled by phantom voltages use an incand. test. light or a Wigglesworth.
    Last edited: Jul 12, 2009
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Are you on 120 volt, or is it a 240 volt system??
  7. Stephie

    Stephie New Member

    Messages:
    5
    Location:
    Australia
    In Australia we're on 240v.
    I was just alittle confused regarding the 4 wires and only having 3 terminals to use.
    I managed to get the light to work by using netural, earth and the switch wire in the terminals of my new light and just by passed the active with a connector.

    Thanks guys. :)
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