Telephone Wiring: How to Add an Extra Extension and Check for Problems

Telephone receiver on a white background.

With the technology and convenience of cordless phones, it is easier than ever to have a telephone right where it is wanted or needed, but cordless phones are not practical in every situation. If left off the cradle for extended periods of time, the battery eventually discharges, and although portable telephone cradles for cordless landline phones are available, they do not always solve the problem.

Telephone jacks are necessary for dial-up modems, fax machines, and some satellite connections. Plug-in portable wireless phone jacks are an option, but they are not cheap, and they are not always practical since they take up valuable outlet space. Sometimes it is necessary to add an extra telephone extension for convenience and practicality. Many people contact the phone company and pay a hefty fee for an extra extension, but it is possible to add an extra extension without hiring a professional.

Phone problems are also a common concern, and many people pay monthly inside wire protection fees. It is wise to sign up for an inside wire protection plan just to make sure the inside wiring is in good working condition. After realizing the telephone wiring is properly connected and in good working condition, paying for inside wiring protection is not necessary, especially if you know how to troubleshoot common telephone wiring problems. It is easier to check for and correct problems than many people realize. You can do it yourself.

The Basics of Standard Four-Wire and Two-Wire Systems

Before beginning, it is important to know the basics of a standard two-wire and four-wire telephone wiring system. Open the junction box and the wiring can look a little confusing. Older homes typically have two-wire lines, and newer homes generally have four-wire systems that allow for more extensions. In a four-wire system, you will typically find eight wires: four white wires and four colored wires. In a two-wire system you will find a total of four colored wires. They are typically green, red, black, and yellow. In a four-wire system, four separate extensions can be run throughout the home.

Each white wire is paired with one colored wire for each extension. In a two-wire system, pair red with green for the first phone line, and pair yellow and black for the second extension. It really is not confusing at all once you understand the basics.

How to Locate the Junction and Run the Cable

Begin by taking the phone receivers off the cradles to prevent the phones from ringing while wiring a new extension. Next, look for the junction box in a utility room, a basement, or another appropriate location. It connects to a standard network interface where your telephone wiring connects to exterior phone wiring. It will have a cover that will require removal. Secure the new cable next to the junction box using a cable staple, and be sure to allow plenty of excess cable for connecting the wires.

Next, run the new cable to the area where you want the telephone extension, and be sure to keep the cable approximately 6 to 8 inches from circuit wiring to avoid any type of electrical interference. Check your local fire code, and attach it with cable staples along baseboards, trim, within walls, inside closets, cupboards, or any other allowable location where it will be hidden from view. Mark the area where the modular extension will be located to make the end of the wire easy to find.

Preparing the Wiring and the Wall

The next step involves preparing the wiring before attempting to make the connection to a new modular extension. Instead of using a knife to strip the wires, use a wire stripping tool with an insulated handle, and remove about two inches of the cable covering and about 1 inch of the wire insulation. To reduce the risk of electric shock, do not plan to connect the wires if it is storming.

A cutout for the extension must be made prior to connecting the wires. Look for the mark made when running the cable. Use a small drywall saw or the appropriate cutting tool for the wall material, pencil it in, and cut out the area where the extension will be placed.

Connecting the Wires

When ready to connect the wires it might look confusing since the colors of the wires at the telephone junction and the extension can vary. Simply connect the wires on the extension to similarly colored wires at the junction. Tape the extra stripped wires with electrical tape, and tape them to the back of the extension to hold them in place. Mount the extension inside the cutout on the wall.

Lastly, connect the wires to the telephone junction. Coordinate the colored wires with the colored screw terminals. Once again, wrap the ends of any extra wires, and push them up into the junction before reattaching the cover.

Troubleshooting Phone Problems

Before calling the phone company when the phones are not working, it is important to test the phones one by one. A single phone that does not work can cause problems throughout the home. Begin by unplugging all of the phones, and test each one separately. If one of the phones does not work, you have found the problem. However, the phone might not be defective.

A bad modular cord can cause a telephone not to work. Attach a modular cord that works to the non-working phone. This could solve the problem. If the telephone still does not work, try using a working extension. If it still does not work, it is defective.

Troubleshooting Wiring

Check the wiring if a telephone works when plugged into one extension but not another. More often than not a single wire has come off of a screw terminal. If none of the phones are working, check the inside cable for damage. Now that you know how to install a new telephone extension, it will be a breeze to check and install a new cable if necessary.