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How to combine two phones into three wires.

Discussion in 'Electronic Basics' started by burt squareman, Nov 18, 2004.

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  1. I need to run two phones from the junction box outside to
    inside. Three wires runs 15 feet into the house (plus ground,
    that makes four.) One of the phone uses only two of the three
    wires. How can I use these three wires to carry two phone
    lines?

    Thanks
     
  2. peterken

    peterken Guest

    in a normal configuration only 2 wires are used, called a and b
    you might parallel all internal phones (connect the 2 wires of the second
    phone to the two wires used by he first etc)
    OR
    you might consider using a phone-central in the house, opening the path to
    internal communication and switch through etc
     
  3. Dbowey

    Dbowey Guest

    burt posted:

    <<
    I need to run two phones from the junction box outside to
    inside. Three wires runs 15 feet into the house (plus ground,
    that makes four.) One of the phone uses only two of the three
    wires. How can I use these three wires to carry two phone
    lines?
    Let me see if I understand...... You have two telephone lines *at* the telco
    Network Interface (NI), and there is a four-wire cable from the NI going into
    the house. Do I have this right?

    The telco interface *must* be grounded by a direct wire from a ground rod or a
    metallic water pipe. Is it?

    If you answer both questions "yes" then you don't have a problem, as there is
    no need to carry a ground into the house within the four-wire cable.

    Use two of the wires for each line/phone.

    Don
     
  4. Dmitri

    Dmitri Guest

    burt squareman wrote:

    A phone line uses a balanced pair, meaning you always have to have two
    conductors per line. That makes it four necessary conductors for two
    lines. Being balanced that they are, they also need to be twisted pairs,
    not just any conductor. Get a piece of CAT3 cable from a Home Depot or
    similar store, and you'll be OK. Make sure the cable is rated for inside
    use if you are planning to continue with this cable into the house. In
    this case you'd need to protect that cable from the elements with a piece
    of a small PVC pipe and corresponding fittings.


    --
    Dmitri Abaimov, RCDD
    http://www.cabling-design.com
    Cabling Forum, color codes, pinouts and other useful resources for
    premises cabling users and pros
    http://www.cabling-design.com/homecabling
    Residential Cabling Guide
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