How To Wire A Video Doorbell

Connecting a video doorbell to wired power should be a simple affair. There are only two wires, after all. If you have an existing doorbell transformer, it should just be a matter of connecting the two wires in your wall to the video doorbell terminals using the provided screws - or so you’d think.

Basic Doorbell Wiring Steps (Existing Transformer)

If you have a mechanical chime and a doorbell transformer already installed, the process should be as simple as this:

  1. Locate the wires from your doorbell transformer at the doorbell location.

  2. Pull out a few inches of wire to give you room to work.

  3. If the wires don’t have any sort of connector on them, you may want to consider attaching ‘fork spade’ terminal connectors to make it easier to get a good connection. Ring sells a spare parts kit for their doorbells that includes spade connector leads and wire nuts, which is probably the easiest way to do this.

  4. Locate the terminals on the back of the video doorbell. These will generally look like a couple of screws side-by-side.

  5. Slot in each wire connector (or wrap the wire around the screw) and secure it.

  6. Tuck the remaining wire back into the wall and mount the doorbell. Be sure not to crush the wires as you put it in place.

You may well be lucky, and this is, in fact, all you need to do. If you don’t have a transformer yet, or it doesn’t suit your video doorbell, then you can run into frustrating problems.

Wiring schematic for a basic doorbell and chime setup

Potential Problems

Issues can arise because of a lack of clear standards around doorbell transformers, the variation in power requirements of video doorbells between different brands and models, and the wildcard of what, if any, chime you have installed. Chimes add extra load and help regulate the power to the doorbell. These installations are generally simpler, but again this depends on the doorbell model as not all video doorbells support wired chimes, or need any special treatment if they do.

Yes, this all gets a bit messy. It’s because of the lack of standards that you’ll often see video doorbell manufacturers specify their power requirements as something like 8-24V 10VA. Doorbell transformer voltages and load ratings vary, so video doorbells need to accommodate a range of possible voltages. What’s more confusing is that some video doorbells require a load resistor to regulate the voltage when not using a mechanical chime, but not all. You can find many of these on the market, but I use the one Ring sells as it’s decent quality (made by hp), insulated, and comes with easy-to-use wire clips.

Wiring schematic for a doorbell that requires a resistor when no chime is present

It’s important to do your homework - preferably before making a purchase - to determine the documented requirements for your particular doorbell for the set up that you have. You’ll need to check the following as these can all affect how you need to wire your doorbell.

  • What is the voltage and load rating of your existing transformer? This will be something like 16V 30VA.

  • What is the power requirement for your video doorbell? This will look similar to the transformer rating.

  • Do you have an existing wired chime installed?

  • Does your video doorbell support wired chimes (support for mechanical or digital chimes will vary).

  • Does your doorbell need a resistor to use without a chime (a direct transformer connection)?

Wired doorbell chime support

If you intend to make use of an existing indoor chime, this adds a whole other level of randomness to the requirements - and potentially wiring. Note that chime support varies quite a bit. Many video doorbells DON’T support wired chimes, and of those that do, only some kinds are covered. Some examples:

The Logitech Circle View doorbell supports the most configurations I’ve seen, but to do that it comes with a whole separate ‘chime kit’ that needs to be wired in depending on your configuration. An interactive setup guide is provided to determine what you’ll need to do and show you where to wire what, so that’s something at least.

Most Ring battery-powered doorbells support mechanical chimes without any special requirements but need a resistor to work without one on a typical doorbell transformer.

Eufy wired doorbells support mechanical chimes only, but prefer to bypass them, so may need a jumper wire to be installed across the chime. No resistor is required with the chime removed from the equation.

Understanding the power requirements

When determining the low-voltage doorbell transformer you need, or troubleshooting power supply issues, it can help to understand what the power requirement specifications mean. Let’s take a brief look at some of the electrical concepts at play.

Understanding the terminology

Firstly, the transformer specifications. There are two parts to this: the voltage, and the load rating. Voltage is straight forward as it’s just the output that the transformer produces from your household supply. The load rating, on the other hand, is specified in VA (Volt Amps) and is the amount of power draw the transformer is rated to handle.

What's with Volt Amps?

VA is unit unfamiliar to many people who would be used to seeing Watts as a load rating. Both Volt Amps and Watts are effectively the same calculation: Volts x Amps. So, why use VA instead? Simply put, it’s because doorbell transformers output AC instead of DC power and this has major implications in calculating actual power draw.

Watts can only be used in DC circuits where the current flow is continuous, and a simple multiplication can provide an accurate indication or power. Because AC cycles between opposing phases the actual current is a wave form, constantly in flux. To calculate the actual power draw at any given point in time is, well, not simple. It’s also not strictly necessary for pairing a power supply to a load, where the approximated figure will do. This is where Volt Amps comes in. It provides an apparent power figure for sizing these components correctly, with some margin for error as the VA rating will be based on the maximum expect current of the circuit.

For a power supply, the VA rating tells you what it can handle.

For the consuming device (the doorbell) it tells you what it is going to draw…or it should.

Can you trust the specs?

Not all doorbell brands are transparent about what they actually need. Sometimes they’re downright confusing. For example, while reviewing the Eufy E340 I came across conflicting documentation and support responses to this question.

The product specs and the in-app instructions stipulate that it MUST have a 16-24V 30VA supply. The support documentation, however, specifies 16-24V 10VA, and Eufy’s support team has provided advice that you can use a plug-in transformer rated at 16V 800mA (16 x 0.8 = 12.8VA). This provides a good example of how the specifications may not actually represent the power draw required. (Eufy has since clarified that they specify 30VA because that’s what most people will have, but that’s not helpful if you don’t)

On the transformer side, a word of caution is in order. These transformers are typically unregulated. This means the output voltage is only delivered at a specific current but will fluctuate under varying loads. Using a high capacity (30 or 40VA) transformer with a video doorbell on it’s own can result in a significant over voltage, depending on the transformer. I was recently testing with 24V 1A (24VA) transformer and found that its output, unloaded, was actually 34V. If your doorbell doesn’t account for this in its circuitry you could be risking permanent damage due to overvoltage.

Mechanical chimes can soak up some of this load, and help stabilize the voltage, and it’s for this reason that some doorbells require the use of a resistor in the circuit when not using a chime. A 25-Ohm 50-Watt resistor provides the correct damping to stabilize these fluctuations and keep the voltage closer to what it’s supposed to be.

The back of a Eufy E340 showing the wire terminal screw connectors

Typical screw-down doorbell wire connectors

A 24VA AC power adapter connected to a wire-bound resistor

A 24VA AC adapter with a resistor attached

A Ring DC doorbell power supply and it's box

The Ring 24V DC power adapter

Using a plug-in adapter

If you don’t currently have a doorbell transformer, it can be a simpler solution to use a plug-in transformer. There are plenty of AC models available, like this one, that provide long wires to help get it to your doorbell from the nearest wall socket. As with a hard-wired transformer, you’ll just need to check it can support the load requirements of the doorbell.

These kinds of plug-in transformers will usually specify their output in Amps (or milliamps), so just multiply that Amp value by the voltage to get the VA so you can compare with the doorbell’s specifications.

Interestingly, some video doorbell models can actually take a DC power supply as well if you’re going this router. Many of Ring’s video doorbell models can use a 24V DC power supply, and Eufy’s also appear to be able to do the same, although again, it’s not very clear in the manual or the app. The E340 specs support page does specify a 19V 600mA DC power supply as an option.

If your doorbell of choice supports DC power, it’s a simpler and safer option as you won’t have to worry about voltage fluctuations and chime wiring.

Frequently Asked Questions

Why is the voltage not clearly defined?

A lack of standards around doorbell transformers mean that video doorbell manufacturers have to cater to a range of different transformer outputs. The specified voltage range on a video doorbell indicates what range it can use. You’ll need to check what your doorbell transformer outputs to match it up.

Why does the chime you have matter?

The presence of a wired chime in the circuit can affect how your need to wired a video doorbell. If your doorbell doesn’t support chimes, you may have to bypass it, or you may need to add a resistor to the circuit to help regulate the voltage if a chime is not present. Specific requirements vary from one doorbell model to the next, so you’ll need to pay careful attention to the documentation.

How is a typical doorbell wired?

A single doorbell button and chime combination is a fairly simple affair consisting of three wires. One wire runs from the transformer to the button, another runs from the button to the chime, with the circuit completed by a third wire that runs from the chime to the transformer. The chime will normally have three terminals labelled something like Front, Trans, and Back. The Front and Back terminals connect to buttons (allowing for two), with the Trans terminal providing the return path to the transformer.

Why bother with doorbell wiring?

Using wire power for your video doorbell is always going to give you a better experience, even if it also supports running on battery. Besides not having to worry about battery charging and lifespan, there are many video doorbells that have features which are only supported on wired power, or simply perform better with a constant supply.

David Mead

David Mead is an IT infrastructure professional with over 20 years of experience across a wide range of hardware and software solutions. David holds numerous IT certifications and has dedicated himself to helping others with technology throughout his career.


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