Turn off power at the breaker
Verify the circuit is de-energized with a voltage tester
Confirm the light switch box has a neutral, hot, and accessible cable path
Check local electrical code before proceeding
Determine whether the doorbell transformer can be powered from the existing switch circuit
Install a doorbell transformer rated for the doorbell system
Mount the transformer in an approved electrical box or location
Run low-voltage doorbell wire from the transformer to the doorbell button and chime
Use the existing switch box only as a source for line voltage if permitted
Connect the transformer primary to the switch circuit hot and neutral as required
Use proper wire connectors for all splices
Keep low-voltage wiring separate from line-voltage wiring
Secure all cables with approved clamps or staples
Restore power and test the transformer output
Test the doorbell button and chime operation
Replace all covers and ensure all boxes are closed
Call a licensed electrician if the switch box lacks a neutral or if code compliance is uncertain