Long story short, necessarily you do not have to turn off the power to replace a doorbell. That is because the button runs on low voltage and draws very amps.
However, it is better safe than sorry. So, the best practice is to turn off the power before starting any electrical work.
Do You Have to Turn Off the Power to Replace a Doorbell?
As a do-it-yourself project, replacing a doorbell is pretty simple. Despite being an electrical project, you can do it without turning off the circuit. That is because the button is run by a low voltage of 24 volts or less. All you have to do is to unscrew the old button and remove the wires to remove the button.
As far as the button is concerned, due to low voltage, you can simply replace the chime without turning off the power. If your bell, chime, and transformer all are functional, your place of interest would be the wires that make up the doorbell circuit.
Most systems in your house have to be powered off before doing anything to them. However, replacing the doorbell does not require turning off the power. That is because the power is stepped down by the doorbell to a safe 16 or even 12 volts with low amps. In other words, your doorbell is an open circuit and it closes upon pushing the button.
As the doorbell and chime work off of low 8 to 24 volts via a transformer from 120 mains, it is technically safe to work without turning off the power if done properly. However, the best practice is to always turn the breaker off when dealing with electricity. Because it is never worth the risk.
A doorbell system has three components. They are-
This component has 120V input and low voltage output. You are not supposed to do anything with it. It might not cause a partial power outage.
This is the component where the low voltage goes. As long as you do not press the doorbell, the circuit is not closed and the voltage is not transmitted to the last component.
Chime is the box inside your house with two phone wires. It is what you mean by a bell sound. This is the component that you are going to replace.
First, remove the old chime and replace it with the new one. Once done, check your wiring against the instructions. You will see that some chimes will support front and rear buttons. Therefore, giving off different sounds. When you have everything put back together, you can test by pressing the button.
Turning Off the Power
To turn off the power, you just simply have to remove the battery. This will disable it given you have a wireless system. All you will need is a screwdriver. You can turn off the breaker supplying power to the doorbell. Although in most scenarios, the breaker will supply other switches or receptacles for some other appliances.
Although not a difficult task, the confusion about whether to turn off the power during the replacement of the doorbell or not comes often. Therefore, if you are going to replace your doorbell soon, this article should make it clear to you what to do.