Oftentimes people may take on their simple electrical tasks upon themselves to save a few bucks. One such installation is wiring a doorbell transformer. It is a very simple task that one may do himself. No point in spending money on such a task.

So, how to wire a doorbell transformer?

The first step is to properly know each individual part and its functions. Then the steps are as follows, turning off the power, stripping the wires and wiring the transformer, and finally, troubleshooting.

So, if you wish to wire a doorbell transformer by yourself, this guide will teach you how to do it. Step by step with thorough explanations. So without further ado, let’s begin.

How To Wire A Doorbell Transformer?  [Step-by-Step Guide]

Why is a Doorbell Transformer Needed?

Doorbell transformers are used so that they may reduce the voltage on your mains before going into the doorbell. As the excess voltage is too much for the small circuit and could even fry it. Let’s discuss this further below.

Fig 1- A Doorbell Transformer
Fig 1- A Doorbell Transformer

Does a doorbell need a dedicated circuit? No, it does not. It receives its power from your regular circuits. Basically, every household is supplied with a voltage between 100 volts and 240 volts.

Depending on where you are and other factors. The task of the doorbell transformer is to reduce that voltage between the values of 10 volts to 24 volts.

Because the doorbell has such a small circuit, it cannot handle the huge 100 volts. If that voltage is applied to the doorbell without decreasing it, it will certainly fry the entire circuitry of your doorbell. And could even result in a fire.

But, how many amps does a doorbell use? It is mostly somewhere around 20 amps. But most households supply 15 amps.

The transformer hence also helps to convert it to 20 amps. Hence it is crucial to install a doorbell transformer to protect your doorbell as well as your household from unwanted electrical hazards.

Does a doorbell have its own breaker? No, it does not. Then what breaker does doorbell go on? Or what size breaker for a doorbell? Well, your regular breakers for light fixtures will always do the trick. Doorbells do not have any special requirements as such.

Steps to Install a Doorbell Transformer

There are a few steps required to wire a doorbell transformer. Such as gathering tools, turning off the power, wiring, etc. I will go through these steps in detail in this segment. How to wire a doorbell from a light switch? I’ll answer that as well.

Gathering Necessary Tools:

Before proceeding with any electrical endeavors, it is highly advised to gather the necessary tools beforehand. And to take proper safety measures to ensure proper safety during the entire task. As electricity is a dangerous subject.

The tools needed to wire a doorbell transformer are listed below:

  • Properly Rated Transformer: Doorbells each have their own power ratings. Both the voltage and the amperage ratings are always written either on the box or the doorbell itself. Before buying the transformer, make sure it complies with the ratings of the doorbell.
  • Rubber Gloves and Boots: These are essential safety measures for any electrical work. These ensure that you do not get accidentally electrocuted in the process. It is highly advised against working on any electrical components without these items.
  • Wire Cutters and Pliers: Wire cutters are needed to cut wires to the proper length as well as to remove extra plastic covering from the wires to reveal the copper wire beneath. So that it may be easier to make the connections.
  • Electrical Tape: Electrical tape is necessary to cover the exposed part of the wire connections. So that they may not short circuit with another bare wire. It also helps to hold the connection in place.

These are some of the tools and items which you have to gather before beginning with the installation procedure.

Turning off the Power:

It is a must to turn off the circuit before proceeding to work on it. You could either turn off the main breaker or the individual circuit breaker.

How to turn off the power from the main panel:

  1. If you want to switch off the electricity from a local circuit breaker, first figure out which circuit breaker supplies power to the outlet you want to turn off.
  2. You may also turn off the main breaker, but this would cut off all power in the house.
  3. Simply turn the switch once you’ve selected the suitable breaker.
  4. Check the LED indication to ensure there is no electricity to the outlet.
  5. If there are no indicators, you can examine the circuit with a non-contact voltage tester.

These are the steps you need to follow to turn off the power to the circuit. This will ensure a safe working environment.

Wiring the Doorbell Transformer:

The wiring is the final and most crucial step of an electrical installation.  The steps to wire a doorbell transformer are provided below with a wiring diagram.

Fig 2- Wiring Diagram for a Doorbell Transformer
Fig 2- Wiring Diagram for a Doorbell Transformer

How to wire a doorbell transformer?

  1. A transformer will have a total of 5 terminals. 3 of which will be for the input, and 2 will be for output.
  2. Strip the wires coming out of your walls about 3/4th of an inch. This will help with the installation procedure and ensure proper contact.
  3. Connect the white neutral wire to the white wire of the transformer.
  4. Attach the hot wire (black) to the black wire coming out of the transformer.
  5. The green wire of the transformer will be connected to the ground of your connection.
  6. Now for the output wires. Connect the black neutral terminal to the black wire or neutral terminal of your doorbell.
  7. The other terminal is for the red wire/positive terminal of your doorbell.

These are the steps o properly wire a doorbell transformer. However, you may also wish to wire a 2 pole GFCI breaker without a neutral. Which is also possible.


After reading through this article, I can guarantee that you now know the ins and outs of how to wire a doorbell transformer. I have also explained why a transformer is a necessary component for a doorbell.

However, if you still feel intimidated by the procedure, feel free to consult a professional.

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