Doorbell Transformer Location: How to Find, Test and Replace It

Maybe your doorbell stopped working, or you want to replace an old transformer.

Finding a doorbell transformer location is not always easy.

But as an expert in the field, I will guide you to find where the doorbell transformer is located in your house. Keep reading!

What is a doorbell transformer?

A doorbell transformer is an electrical device that steps down the household current from 120 V to about 10-24 volts required by smart doorbells.

It is a brass- or silver-colored box of about 2 to 3 inches square, containing two to three terminal screws on the face.

You can install a transformer anywhere in the house, but most electricians fix it on the electrical panel or inside the circuit breaker box.

Once you locate the transformer, troubleshooting or upgrading to a smart doorbell can be easy.

Related article: How to test a doorbell transformer

What is the work of a doorbell transformer?

The role of a doorbell transformer is to step down the 120v, or 240v alternating current to a lower voltage, usually about 10 to 24 volts which can be used by the doorbell.

How to find a doorbell transformer.

While some transformers can be located inside the doorbell’s chimes or bell enclosure, others can be elsewhere. Below are the places to find your bell transformer.

Doorbell transformer location number one: electrical panel.

The electrical panel is the most common place to locate your doorbell transformer. This is because of its open nature. It also hastens replacement if the transformer spoils.

It is usually the best place to look for your doorbell transformer, however, not all electricians install the transformer there.

Doorbell transformer location number two: Garage

We have seen many transformers installed in the garage. This is because of their easy access.

Normally, a doorbell transformer is surface mounted to avoid overheating.

While looking for your transformer in the garage, check around the front door, communication cables, or near any outlets in your garage, hopefully, you will see it.

But if you do not, never lose hope. Instead, check the next location.

Transformer location number 3: Near the security system.

Sometimes, the doorbell transformers are located near the security system. So while looking for your transformer, look around the security system. Check near the system keypad and the control station and it might be there.

Also, some security systems such as the intercom have the transformer tied inside them.

Location Number 4: Closet.

Your closet is also a good place to look for your transformer. Look inside the closet, check above the closet door and on the front wall, it might be there.

Check your furnace closet

Look above the closet door and along the walls, you might see the bell transformer.

Check the attic or basement.

Gain access to the attic and check around the front door and above the doorbell location.

Look beneath the stairs in the basement, the transformer may be there.

Check beneath your stairwell

Look under the stairwell of a two-story building and if you have a storage area under the stairs, check it. Some installers fix the transformers in such a hidden area.

How to test the doorbell transformer

Once you have seen the location of the transformer, check the wiring system to see if it is correct.

To check the wiring, see our article on how to wire a doorbell.

If the wiring system is correct, check the transformer with a digital multimeter to know if it is functional.

For details on how to test a transformer, read our article on how to test a doorbell transformer.

How to replace a doorbell transformer

Replacing a faulty transformer is quite easy once you have found its location.

Tools and materials required for the installations

  • New transformer
  • Screwdriver
  • Wire stripper
  • Electrical tape
  • Wire nut
  • Flashlight
  • Multimeter

Installation procedures

Turn off the main circuit breaker

Locate the circuit breaker box that controls all the lights in your home and turn it off. This is to make sure there is no power supply to the whole electrical system.

Disconnect and remove the old transformer

A doorbell transformer is usually installed at the junction box, or inside the electrical panel. Locate the transformer, loosen the screws and remove the wires connecting the transformer to doorbell and electricity.

Keep the screws safe and pull out the transformer.

Note: Make sure the new one is compatible with the old one.

Connect and install the new transformer

A doorbell transformer comes with three wires, one black or hot wire, a neutral and an earth wire.

Mount the new transformer inside the junction box and complete the wire connections.

Connect the black wire from the doorbell transformer to the black wire from power supply, the white or neutral to neutral, and the earth wire (green or brown) to the earth terminal. Cover the connections with wire nuts.

Connect the two wires from the chime and push button to the two screw terminals at the bottom of the transformer to complete the connection.

Switch ON the power supply and test your work

Once you are through with the wire connection, turn on the main switch that supplies power to the doorbell and test run your work.

How much does it cost to replace a doorbell transformer?

Currently, a new transformer costs about 13 to $24 amazon, and the cost of hiring an electrician is around $150 to $250.

So, the cost of replacing a doorbell transformer is around 12 to $24 if you can install the transformer yourself, and around 200 to $300 if you will hire an electrician.


Because I have seen what some people pass through just to locate their smart bell transformer, I have made a list of where to find it. And how to test and replace a faulty transformer.

Hope it helps.

To buy a new doorbell, get it here at Amazon

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About mariaelectricals

Hi, I am Emmanuel Nwankwo, a commercial electrician and the founder of I established this blog to share my decades of work experience in electrical installations and repairs.