Electricity: Doorbells and Chimes

A doorbell or chime system consists of the sounding device, a front-door button, an optional rear-door button and a transformer that reduces 120-volt current to the lower voltage most systems require. Bell wire connects the components. The transformer must be connected to an unswitched branch circuit in a junction box, often in the basement or near the service panel.

When estimating cable, measure the distances between components and add another 15 ft. (4.5 m) for connections and route turns. Follow the manufacturer’s instructions. Although bell wire can be exposed, fish it behind finished surfaces where possible.

If you’re replacing a doorbell, check the old transformer to make sure it has the same voltage rating. Replace the transformer, if necessary. Before repairing a doorbell, check the service panel for a tripped breaker or blown fuse.

Installing a Doorbell or Chimes

1. With power off, remove a knockout from the junction box; insert transformer wires. Fasten transformer to box with locknut. Use wire connectors to join one transformer wire to a black wire, the other to a white wire.

2. Drill holes for door button wires and mounting screws at doorknob height adjacent to the door’s edge. After running the bell wiring, connect one wire from the transformer and one from the bell or chime unit to the button’s terminal screws.