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, this is not typically recommended. More specifically, it may work but your doorbell will likely sound louder than it was intended to.
We’ll 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.
What Is A Doorbell Transformer?
For most circuits, household current is usually 120 volts. However, there are a few circuits such as electric clothing 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 needed to activate the chime. This is where the doorbell transformer comes in.
Your doorbell transformer is a device that converts line-voltage into low voltage to be used in conjunction with your doorbell. Its main 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 the 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.
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 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.
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 passes through the transformer.
When in doubt or if you ever feel uncomfortable handling electrical devices, seek help from a professional, licensed electrician.
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 over voltage 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 sound bar 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 wirewound resistor is an electrical device that restricts or limits the current electrical 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, for whatever reason, your doorbell is not working you may want to begin with checking if the issue is a faulty transformer. The first step in this process is finding the transformer as they can often be difficult 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.
- Take your voltage meter and adjust it to 25 VAC.
- 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.
- Using the reader on the voltage meter, compare it to the transformer’s voltage requirements.
- 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.
- 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.
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’s likely that by doing this you’ll experience a louder, buzzier chime. However, this can be avoided by installing a wirewound 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).”