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What Size Transformer for Nest Hello?

Last Updated Mar 4, 2022
nest doorbell
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In the world of smart doorbells, only a couple of brands consistently stand out year after year, including Google’s Nest brand. The Nest brand always impresses with its feature set, upgradability, and ease of use. Furthermore, homeowners can install the doorbells on their own without requiring an electrician, further enhancing their value. For those who fear installing the device on their own, one of the biggest questions is regarding what wiring decisions they need to make.

For the Nest Hello, a 16V transformer is the most appropriate choice. While you technically can use a 24V transformer for the Nest, it is not recommended. To ensure your Nest Hello is protected while it’s protecting your home, a 24V transformer is the best option.

If you’re ready to install your own Nest Hello or need to change the tranformer, and need more information on the right size transformer for the job, you’ve come to the right place. Keep reading for more on what size transformer you need for Nest Hello.

Can I Use a 24V Transformer on a 16V Doorbell?

Bigger is not always better in the electrical world, so using a transformer with a higher voltage doesn’t equal better performance.

You can use a 24V transformer, but it is not recommended and may not be completely safe. These doorbells will list the transformer they require to work properly but can often go within 20% above or below this requirement. When doing the simple math, 20% in this scenario would equal approximately 5V. This means a 24V transformer is not a real option.

Going into more depth, the overvoltage that results in using a 24V transformer on a 16V Nest would more than likely result in damage to at least the doorbell. The major risk here is the possibility of fire which is far more dangerous than just damaging the device.

What Power Supply Do I Need for Nest Hello?

There are a total of three options for power supplies for the Nest Hello, including battery power, hard wiring your Nest Doorbell, or going with an AC adapter.

Here’s a little more on each of those options:

  • Nest Doorbell (Battery): Just as it sounds, this version of the doorbell has a rechargeable battery that the user just needs to plug in when it’s low.
  • Nest Doorbell (Hard wired): Although this is technically one version, it gives the user two options. The installer can use the home’s existing doorbell wiring to connect directly. This power supply needs to have at least 16V of power to work properly, posing a problem to older homes.
  • Nest Doorbell (AC Adapter): To make up for older homes that are incapable of providing enough power to run the doorbell, an aftermarket AC adapter is available. A small hole would need to be made to the outside near the Nest then connected through to an outlet inside. These adapters can be purchased by Google directly or places like Amazon.

How Do I Increase My Nest Voltage to Hello?

As previously stated, older homes often do not provide enough consistent voltage to allow the Nest Hello to work properly. There are a couple of ways to increase the voltage enough to make it work well for you. You can replace the original transformer, or you can try an AC adapter.

Replacing the transformer with a newer, more consistent one is the most direct way since your home already has it somewhere. The problem is they can be difficult to find in much older homes.

Another way goes back to using an aftermarket AC adapter. This method can be cumbersome because it involves drilling a new hole into your wall. Also, there is the added cost of the AC adapter, which will most likely be higher than the cost of a new transformer. Either method should get your Hello enough voltage to work as intended.

How Do I Know What Voltage My Doorbell Transformer Is?

So, you know what voltage your doorbell transformer needs to be, but how do you know what your existing voltage is? It is a fairly simple four-part process using a basic multimeter that can be found at any hardware store:

  1. First, disconnect the wires to your existing doorbell while making sure they do not slide down behind the wall (which creates way more work than you want to get into for this exercise).
  2. Adjust the knob on the multimeter to AC.
  3. Attach the probes on the meter to the wires from the doorbell.
  4. The display will show what your current voltage is, which hopefully coincides with what the Nest requires.

Simply looking at the existing transformer is another way to find the voltage of a transformer if you do not want to use a multimeter. One must remember to shut off the power to the breaker connected to the transformer to make sure no harm comes to anyone.

Another point to make here is that the transformer could be showing its age or faulty, which would make a multimeter a necessity.

Final Thoughts

The Nest Hello doorbell from Google has become one of the most popular options homeowners have to enter the smart home space. The combination of features, upgradeable software, and ease of use make it very difficult to beat. Furthermore, Google has made it very easy for most people to install whether they have an electrical background or not.

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