How to test house telephone wiring

Written by contributing writer
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Repairing or installing your own telephone wiring can save you a lot of money. The task isn't impossibly difficult even for the modest do-it-yourselfer; as with any electrical work, it is vital that all of your wiring is properly isolated. A short between two of the wires in your home's telephone wiring can cause your telephone service to become inoperable. Using a multimeter, you can quickly diagnose potential problems in your home's telephone wiring.

Skill level:

Things you need

  • Multimeter
  • Telephone

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  1. 1

    Test for signal at the network interface. The network interface is usually near your home's electrical meter. This will let you know that you are getting a telephone signal from your telephone company. Open the side of the interface that you can access and plug a phone directly into one of the phone jacks. If you are not getting a signal here, your wiring may not be at fault. If you get a dial tone, you know the telephone company is sending signal to your home. Read on.

  2. 2

    Disconnect the phone company's wires at the network interface, junction block or entrance bridge. Some homes may not have accessible network interfaces. If you cannot get to your network interface, you can probably access a junction block or entrance bridge. Wires should run from your network interface to the junction block or entrance bridge, which may be located outside your home or in a basement or utility room.

  3. 3

    Unplug all of your phone jacks. This will complete the process of opening the wiring circuit. Each of the telephone wires should be an independent circuit. Problems arise when two bare wires touch, which may happen either at phone jacks or somewhere inside the wall.

  4. 4

    Set your multimeter to test continuity. The continuity setting tells you if two points are connected to each other electrically. Since all of the telephone wires should be isolated, you do not want continuity between any two of your wires.

  5. 5

    Test the wires one pair at a time. You can test the wires at the network interface, junction block or entrance bridge. Connect the leads of the multimeter to two separate wires. You should not receive a continuity reading. Check all of the wires against each other. If any two wires do give you a continuity reading, you have a short somewhere between those two wires.

  6. 6

    Troubleshoot your connections. If you find a short in your wires, you need to find the location of the problem and remedy it. The shorts typically happen either at phone jacks or at the network interface, junction block, or entrance bridge. Visually inspect the wires at all of these connections, separate any wires that are touching, and retest for continuity.

  7. 7

    Reattach the wires and test for a dial tone. Make sure the wires coming from the phone company and all of the connections you tested are properly reattached so that none of the wires are touching. Plug a telephone into all of your phone jacks in turn, and listen for a dial tone.

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