how to change doorbell transformer

Can I Use A 24V Transformer On A 16V Doorbell?

Are you having some difficulty determining the correct transformer to pair with your doorbell? If you've recently purchased a new doorbell and already have an existing transformer, you probably have some questions. While all doorbells will come with specific instructions and voltage requirements, you may be wondering if you can use a 24V transformer on a 16V doorbell.

In short, although possible, it is typically not recommended to use a 24V transformer on a 16V doorbell. More specifically, it may work, but your doorbell will likely sound louder than it was intended to. You may also experience a buzzing noise, and it will eventually wear out your doorbell.

We will explore the reasons for this in further detail and also provide you with some vital information in regards to your doorbell, transformer, and adding a resistor into the mix, if necessary. This will help you understand why it's not a good idea to add a 24V transformer to a 16V doorbell; we will explain what you can do instead.

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Table of Contents

What Is A Doorbell Transformer?
- Doorbell Voltage Specifics
How Does A Doorbell Switch Work?
- How Does The Doorbell Chime Function?
Electrical Safety Regarding Doorbells
Can I Use A 24 Volt Transformer On A 16 Volt Doorbell?
- What Is A Wirewound Resistor?
How To Find And Test A Doorbell Transformer
- How To Test Your Doorbell Transformer
Related Questions
- Do I need a doorbell transformer?
- What is the color coding on the transformer's small-gauge wires?
- Is the doorbell transformer in the chime?
Wrapping It Up
- Related Articles

What Is A Doorbell Transformer?

For most circuits, the household current is usually 120 volts. However, there are a few circuits, such as electric clothes dryers, that will require 240 volts. Doorbells have a very low voltage requirement and therefore need a way of converting those 120 volts down to the 8, 16, or 24 volts required to activate the chime. This is where the doorbell transformer comes in.

Your doorbell transformer is a device that converts line-voltage into a low voltage to be used in conjunction with your doorbell. Its primary purpose is to keep wired doorbells powered at the correct voltage for optimal operation.

The higher voltage will begin at the transformer, where it will transfer through a system of wiring that is wound around an iron core. As the current exits the transformer through the output wire, it produces a lower voltage.

Doorbell Voltage Specifics

As previously mentioned, doorbells operate on a very low voltage. Most older models will require between 8 and 20 volts, with the most common being 16 volts. However, newer doorbell models require 24 volts of electricity. The higher voltage is designed to accommodate larger homes with longer runs of wire.

The doorbell system includes the transformer that converts the voltages and a switch for completing the circuit, resulting in the bell or chime sound. Find out how to fix a doorbell that keeps ringing.

How Does A Doorbell Switch Work?

Leading from the transformer to the doorbell chime is a series of thin wires. For such a low voltage, small gauge wires are all that is needed here. The switch simply refers to the button on the outside of your home that triggers the bell or chime. By pushing the button, you complete the circuit, interrupt the flow of electricity, and ultimately cause the doorbell to ring.

How Does The Doorbell Chime Function?

Once the current reaches the doorbell chime, it initiates the piston. As electricity goes through an electromagnet, the piston fires resulting in the doorbell tone sound we are all familiar with.

Electrical Safety Regarding Doorbells

Thankfully since doorbells work on such a low voltage, if you need to test, install, or maintain one, you can do so with a low risk of injury. However, when you're working with electricity, you should always verify the voltage and turn off the electricity to the circuit before proceeding with any work.

Use a voltage meter or other type of electrical testing device to check the voltage that you will be working with. For example, if you're dealing with a failed transformer, it won't be reducing or converting the voltage. It is very probable that the output is the same as the 120 volts that pass through the transformer.

When in doubt or if you ever feel uncomfortable handling electrical devices, seek help from a professional, licensed electrician. It's better to be safe than sorry. Or, you can always reach out to a friend or family member who has more experience working with electrical projects if you don't have the funds to hire an electrician. Check this out so you can easily find your doorbell transformer.

Can I Use A 24 Volt Transformer On A 16 Volt Doorbell?

Now that you better understand how doorbells and their transformers function, let's dive into this question. If the doorbell is rated for 16 volts and your transformer is putting out 24 volts, you have an overvoltage of almost 50%.

What this means is that whether or not you will have proper functionality will depend largely on the construction quality, design, and voltage requirements of your particular doorbell. That's not to say that it won't work. More than likely, it will, but it will sound louder, and you may experience a buzzing noise.

This is caused by the increased voltage making the piston hit the soundbar at a harder and faster rate. Therefore, it is not recommended to use a 24v transformer with a 16v doorbell to achieve correct operation. One way you can get around this is by installing a resistor.

What Is A Wirewound Resistor?

Although it's not recommended to pair a 24-volt transformer with a 16-volt doorbell, there is a way you can get away with it without any changes in the sound of your doorbell. If you want to use the 24-volt transformer, you can add a resistor in a series with one of the wires.

A wire-wound resistor is an electrical device that restricts or limits the electrical current flow within a circuit. If you choose to install a resistor to your doorbell, it will reduce the amount of voltage that is "seen" by the doorbell to the accepted amount of 16 volts.

How To Find And Test A Doorbell Transformer

If your doorbell is not working for whatever reason, you may want to begin by checking if the issue is a faulty transformer. The first step in this process is finding the transformer, as they can often be challenging to locate.

The doorbell transformer will almost always be tucked out of view. It could be housed in the bell enclosure and the doorbell's chimes but is most often found elsewhere. If you have visibility to where the doorbells' wires run, you can try tracing them back to where the transformer will be connected. If this doesn't work, try checking one of the following places to locate your transformer:

High up on a garage wall, in plain sight
A floor joist in your basement
In your entryway closet or another nearby closet
Beneath the doorbell chimes or bell
In your attic (perhaps buried underneath insulation)
In a crawlspace
Near the electrical panel or doorbell inside of its own electrical box

Once you've located the transformer, make a note of the voltage rating listed on the device, you'll need this for testing.

How To Test Your Doorbell Transformer

Follow the below steps to test a possible faulty transformer.

Adjust your voltage meter. Take your voltage meter and adjust it to 25 VAC.
Connect the meter to the transformer. Using the probes on the meter, touch them to the two flat screws on the transformer. These screws connect the small-gauge doorbell wires to the transformer.
Compare the reading. Using the reader on the voltage meter, compare it to the transformer's voltage requirements.
Turn off the power. If it's too low or exceeds the voltage requirement, turn off the power to the transformer before doing any more work on the system.
Get a new transformer. Replace your transformer with a brand new one.

Do I need a doorbell transformer?

Yes, you will need a transformer if you have a wired doorbell. Since doorbells work on a low voltage, they will not work without something to convert the high voltage into a lower, more usable voltage. However, some battery-powered doorbells bypass the need for a transformer but can have many limitations.

What is the color coding on the transformer's small-gauge wires?

The three small-gauge wires connect the transformer to the rest of the electrical system in your home. In general, green will be the ground wire, white is your neutral wire, and black is the hot, live wire.

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Wrapping It Up

If you are installing a new doorbell that is rated for 16 volts but want to recycle your 24-volt transformer, although not recommended, it may work. It is likely that by doing this, you will experience a louder, buzzier chime. However, this can be avoided by installing a wire-wound resistor to reduce the amount of voltage that goes to the doorbell.

For more great doorbell-related reads check out, "What's The Best Ring Doorbell Angle Mount?" and "7 Home Intercom System Replacement Ideas (You'll Love)."

How To Fix A Doorbell That Keeps Ringing (Do This!)
Can't Find The Doorbell Transformer? (Look Here)

Jessica Stone

Jessica considers herself a home improvement and design enthusiast. She grew up surrounded by constant home improvement projects and owes most of what she knows to helping her dad renovate her childhood home. Being a Los Angeles resident, Jessica spends a lot of her time looking for her next DIY project and sharing her love for home design.

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