Each circuit breaker should be labeled.
Your electrical panel should have labels next to each switch, or circuit breaker. Your current mechanical doorbell should be labeled.
My doorbell breaker is not labeled. What now?
Consult a professional.
If you do not feel comfortable working with electrical systems, please consult a local professional electrician for help. They will be able to provide hands-on assistance or detailed instructions to identify the correct circuit breaker.
Try to Do-it-Yourself.
If you are comfortable and want to try figuring out your electrical system yourself, you can use some trial and error. At your electrical panel, try turning OFF individual breakers to identify which one controls your current doorbell.
- Important: Test your electrical system at your own discretion and risk. Testing your circuit breakers may cut power to your appliances. Make sure to return your circuit breakers to their original ON or OFF position when you're finished.
If you are comfortable with electrical works, you could try it with trial and error methods, to identify which switch controls the doorbell. Please be careful about the possible consequences of cutting power to any appliances in your house.
If you have identified your doorbell transformer to be 16-24V AC