Hooking Up a Door Bell to a Transformer

Doorbells operate with power supplied by a transformer that reduces 120-volt house current to voltages ranging between nine and 24 volts depending on the bell or chime system in use. The transformer is usually hard wired to a junction box or the home’s main electrical panel. Once the appropriate gauge electrical wire has been run, you can hook up the doorbell to the transformer with basic wiring skills.

Voltmeter
Wire strippers
Needle-nose pliers
Flathead screwdriver

Instructions

- 1
  Turn off the electrical power to the doorbell transformer.
- 2
  Test the transformer's two output terminals with a voltmeter to ensure no power exists. Place one probe of the tester on either terminal and the other probe on the remaining terminal. A voltage reading of zero (0) verifies that the power is off. If you get any other reading, you need to check your circuit breaker again to ensure that no power runs to the system while you are working on it.
- 3
  Strip 1/2 an inch of insulation from the doorbell wire and the bell switch wire using wire strippers. Doorbell wire is typically 18-gauge solid copper.
- 4
  Bend a loop in each end of the stripped wires using a pair of needle-nose pliers.
- 5
  Loosen the two terminal screws on the transformer using a flathead screwdriver. Turn the screws counterclockwise.
- 6
  Attach one wire to either terminal and tighten the terminal screw clockwise with the screwdriver. Connect the other wire to the remaining terminal and tighten.
- 7
  Restore electrical power.

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