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What are the power requirements for Alarm.com Video Doorbells?

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Power requirements

The following values represent the full compatibility range for AC and DC power sources across all compatible wiring setups. Depending on the specific wiring setup, you may need a higher-rated power source than what is shown on the low end of the range.

Power source ADC-VDB750 ADC-VDB770* ADC-VDB775
AC transformer 16-24 VAC, 10-40 V 16-30 VAC, 10-30 VA 16-24 VAC, 10-40 VA
DC transformer 15-24 VDC, 6-20 W 15-30 VDC, 8 W Wired chime
  • 18-24 VDC, 12-30 W
No wired chime
  • 15-24 VDC, 8-20 W

*Important: The Power Module (ADC-VDBA-PM) included with the ADC-VDB770 is required for every installation. For more information about the power module, see Power module for the ADC-VDB770 - User Guide.

Power accessories
Accessory SKU Hardware type Compatible devices
ADC-VDBA-770BAT 770 Replacement battery ADC-VDB770
ADC-VDBA-770BLI Battery-Less Insert ADC-VDB770
ADC-VDBA-775-PM 775 Power Module ADC-VDB775
ADC-VDBA-MCD Mechanical Chime Dongle ADC-VDB770
ADC-VDB775
ADC-VDBA-PM 770 Power Module ADC-VDB770
ADC-VDBA-PM-750 750 Power Module ADC-VDB750
ADC-VDBA-PM-INT Power Module (International only) ADC-VDB750
ADC-VDB770
ADC-VDBA-PSU-DC DC Power Supply ADC-VDB750
ADC-VDB770
ADC-VDB775
ADC-VDBA-PSU-DC-R DC Power Supply with Resistor ADC-VDB750
ADC-VDB770
ADC-VDB775
ADC-VDBA-RES-10W-10OHM 10 W, 10 ohm resistor pack ADC-VDB750
ADC-VDB770
ADC-VDB775

For multiple Alarm.com Video Doorbells

An additional 10 VA must be supplied for each additional Alarm.com Video Doorbell connected to the same transformer (i.e., two Video Doorbells would require at least 20 VA).

Notice: Alarm.com has not tested or verified support for wiring different Alarm.com Video Doorbell models on the same circuit. It is recommended to use a separate power source and wiring circuit for different Video Doorbell models (e.g., an ADC-VDB750 should not be wired to the same power source as an ADC-VDB775).

For more information about wiring, see:

Supported American Wire Gauge (AWG)

18-20 gauge wire (AWG) is supported for all video doorbell camera installations. 18-20 AWG provides the correct amount of resistance needed to power a video doorbell camera.

Gauges outside of these recommendations affect the resistance of the wire and may deliver incorrect power to the device. 

Verifying the Video Doorbell is receiving enough power

Testing the transformer and wiring

After installing a transformer with a rating that matches your Alarm.com Video Doorbell's power requirements, it is important to test the system on-site to verify the Video Doorbell will receive sufficient power under all conditions. High resistance wiring, poor transformer performance under load, or unexpected components in the circuit can result in performance issues that may not be immediately evident when the device is first powered on.

Replacing the transformer

If the transformer needs to be upgraded, we recommend installing a transformer with voltage and power ratings above the minimum required by the Video Doorbell (e.g. upgrade to 24 VAC, 20 VA transformer) to accommodate the multiple potential causes of insufficient power to the doorbell. In cases where the resistance of the wiring is the primary cause, a higher-rated transformer than what was originally installed will be required to avoid replacing the wiring.

In cases where it is not possible to fully replace the transformer (e.g., an electrician is required), the transformer can instead be bypassed by removing the wires from the low voltage (secondary) side of the existing transformer and connecting those to a plug-in style AC transformer.

Run the AC Power Check tool

If the device is powered by an AC transformer, the AC Power Check tool can be used to verify the Video Doorbell is receiving enough power. This check can be run using the Partner Portal or Partner MobileTech app.

Note: The ADC-VDB750 must be on firmware version 02089+ in order to run the AC Power Check.

Using the Partner Portal:
  1. Log in to the Partner Portal.
  2. Find the customer account.
  3. Click Equipment.
  4. Click Video Devices.
  5. Using the Video Device dropdown menu, select the desired video device.
  6. In AC Power Check, click Run.
  7. Click to select the accessories currently installed.
  8. Click Run again to start the test. Wait about 20 seconds to view the results.
Using the Partner MobileTech app:
  1. Log in to the Partner MobileTech app.
  2. Find the customer account.
  3. Tap Equipment.
  4. Tap Video Devices.
  5. Find the desired video device and tap Go to Device.
  6. Tap AC Power Check.
  7. Tap to select the accessories currently installed.
  8. Tap Run to start the test. Wait about 20 seconds to view the results.
Possible results of the test

The language used to relay the results of the AC Power Check vary slightly between Alarm.com Video Doorbell models. Select the Video Doorbell you are testing to view possible results.

ADC-VDB750 results
  • The doorbell circuit is in good condition and is expected to be able to power the device. No action is required.
  • The doorbell circuit is not supplying the expected power to the device, which could result in performance issues such as power loss after the button is pressed. If the device is wired to a MECHANICAL CHIME, the Mechanical Chime Dongle (ADC-VDBA-MCD) should be installed to improve the delivered power to an acceptable level (if the Mechanical Chime Dongle was already installed before running this test or is not available, then the power source should be replaced). If the device is wired to a DIGITAL CHIME or there is NO WIRED CHIME, the power source should be replaced.
  • The doorbell circuit is not supplying the expected voltage. If wired to a MECHANICAL CHIME, this could result in undesired chime behavior such as rattling/humming after a button press. The Mechanical Chime Dongle (ADC-VDBA-MCD) should be installed. If the Mechanical Chime Dongle is not available, a resistor (included in the box) can be used instead. If the Mechanical Chime Dongle or resistor was already installed before running this test, no action is required. If the device is wired to a DIGITAL CHIME or there is NO WIRED CHIME, no action is required.
  • The doorbell circuit is not supplying sufficient power to the device. The power source should be replaced.
  • A DC power source was detected. This test can only be used for AC power sources.
ADC-VDB770 results
  • PASS
  • PASS (MARGINAL)
    • The transformer was able to power the device through the test, but the AC Voltage detected indicates that there may be insufficient power delivered during times of peak usage or as the transformer performance degrades over time. This device may experience performance issues such as low speaker volume or the indoor chime not ringing. Please consider upgrading the transformer to ensure stable performance.
  • FAIL
    • The transformer was not able to power the device through the test. Please upgrade the transformer to ensure stable performance.
ADC-VDB775 results
  • The doorbell circuit is in good condition and is expected to be able to power the device. No action is required.
  • The doorbell circuit is not supplying sufficient power to the device. The power source should be replaced.
  • A DC power source was detected. This test can only be used for AC power sources.

Note: The results of the AC Power Check tool for the ADC-VDB750 and ADC-VDB775 may cause a trouble condition to appear on the Partner Portal and Alarm.com customer website.

AC Voltage for the ADC-VDB770

The AC Voltage of the ADC-VDB770 can also be retrieved at any time to verify the voltage received by the device under specific conditions.

The AC Voltage value is expected to fluctuate based on the state of the device (e.g., AC Voltage may drop when streaming video with active Two-Way Audio). This value should be disregarded if the power source to the doorbell is DC.

AC Voltage values below 12 VAC indicate that the ADC-VDB770 is not receiving enough power and that the transformer may need to be upgraded. However, AC Voltage values above 12 VAC do not necessarily indicate that the device will receive enough power under all conditions. It is recommended to use the AC Power Check tool to verify the AC Voltage in a high-power condition.

To view the AC Voltage for the ADC-VDB770
Using the Partner Portal:
  1. Log in to the Partner Portal.
  2. Find the customer account.
  3. Click Equipment.
  4. Click Video Devices.
  5. Using the Video Device dropdown menu, select the desired video device.
  6. In AC Voltage, click the refresh button to load the current value.
Using the Partner MobileTech app:
  1. Log in to the Partner MobileTech app.
  2. Find the customer account.
  3. Tap Equipment.
  4. Tap Video Devices.
  5. Find the desired video device and tap Go to Device.
  6. In AC Voltage, click the refresh button to load the current value.
DC power

If the device is powered by a DC source (e.g., ADC-VDBA-PSU-DC):

  1. Verify the wiring. For information about wiring an Alarm.com Video Doorbell, see:
  2. Disconnect the Video Doorbell from the circuit and use a digital multimeter (or similar device) to measure the voltage and current at the two wires that were connected to the doorbell. Verify that they are within the rated range.