How to Replace Doorbells & Transformers

Many houses have low-voltage doorbells with a small transformer that plugs into an electrical outlet or is hard-wired at an electrical box. Over time, the button on the outside wall can wear or become damaged and continued use may short out the transformer. For hard-wired transformers, enlist an electrician to change the transformer, and you can pull the new wires and install the new button. A do-it-yourself homeowner can replace a doorbell with a plug-in transformer in a short time and pull the wires with a method used by professionals.


Unplug the transformer from the electrical outlet. Loosen the screws at the wire terminals on the back end of the transformer with a screwdriver. Pull off the end of each wire from the corresponding terminal screw. Discard the transformer.


Twist the bare ends of the wires together by hand. Twist the bare ends of the new doorbell wires together by hand and align the twists of each pair of wires side by side, similar to making an overlapping splice. Secure the sets of wires together at the splice with several tight wraps of electrical tape. The wraps of tape extend past the bare end of the wires and onto the wire insulation.


Stretch out the wires and apply a light coat of white lithium grease as lubricant for pulling the wires through the walls to the doorbell button.


Remove the doorbell button from the wall at the outside of the house using a screwdriver. Ask an assistant to feed the other end of the wires as you pull the wires out of the wall by hand. Stop when the taped splice is just outside of the wall. Pull off the electrical tape and undo the splice. Discard the old wires.


Attach the end of each wire onto one of the terminal screws at the back of the new doorbell button. Tighten the screws. Push the excess wire into the hole at the wall and mount the button on the wall with the provided screws or double-stick tape from the doorbell kit.


Attach the opposite ends of each wire onto the terminals at the back of the new plug-in transformer and tighten the screws securely. Plug in the transformer at the outlet.