How to Wire a Door Intercom

Updated April 17, 2017

Door intercoms are a common feature in many homes and offices. An intercom, also referred to as talkback phone, is basically a part of an independent electronic communication system used for limited entrance door conversations. A door intercom is mounted near the entrance to a house or an office and serves as a stand-alone communication device. If you want to add extra security to your home, you may want to know how to properly wire and connect a door intercom.

Turn off the power to the entrance door area. It is an essential and important step every time you are dealing with electricity.

Remove the cover of the doorbell button with a Phillips head screwdriver and set it aside. This way, you will be able to access the wiring behind it. Note that this is the outside doorbell button, the one that visitors press at your entrance door.

Disconnect the wires behind the doorbell button. Sometimes there is a small switch that needs to be pressed with a flathead screwdriver in order to detach the wiring.

Hold the new mounting bracket for your intercom against the wall, over the wiring behind the old doorbell. There are pre-drilled holes on the bracket and mounting screws in the installation kit as well. Use them along with a screwdriver to attach the bracket in its place.

Connect the wires to your new intercom doorbell assembly, following the instruction for the particular model you purchased.

Locate the existing transformer near your entrance door and run the wires from the doorbell to the AC adaptor from your new intercom. Connect the intercom adaptor to the transformer. Note that the transformer is actually an electrical housing located near your door, inside the house.

Disconnect the wires from the doorbell inside the house. Notice that this is not the outside doorbell assembly from Step 4, but the doorbell itself: the part of the system that produces the sound. You can twist the wires and then cover their ends with a wire connector.

Mount your new doorbell intercom to the wall. Make sure to find a suitable location for the intercom housing. Usually the manufacturer will recommend the best location. Drill the holes in the wall with a power drill and attach the intercom with screws.

Turn the power back on now that the installation and wiring process is completed. Test your new doorbell intercom with the help of another person.


Make sure to follow the instructions on the installation package since there might be slight differences in wiring different kinds of doorbell intercom systems.


Be extremely careful when working with electricity and make sure to follow all safety precautions for this type of work.

Things You'll Need

  • Phillips head screwdriver
  • Flat head screwdriver
  • Wire connectors
  • Power drill
  • Screws
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About the Author

Based in New Jersey, Susan Raphael has been writing technology-related articles since 1991. Her work has appeared in “Wired” magazine, and “Mac Addict” magazine. Raphael received the Janet B. Smith Literary Award in 2002. She holds a Bachelor of Science in journalism from New York University.