why is my outdoor nest cam making a constant humming or buzzing sound? it's not the fan, it's like an electrical buzz

Diagnosis

The constant electrical humming or buzzing sound emanating from your Google Nest Cam Outdoor Wired is almost certainly caused by "coil whine," specifically originating from the AC power adapter (the transformer brick). This occurs when the inductor coils inside the power supply vibrate at a high frequency due to the electromagnetic field created by the current passing through them. When these vibrations hit a frequency audible to humans, it manifests as a persistent, high-pitched buzz or hum. This is rarely an issue with the camera head itself, as the camera contains very few moving parts or high-voltage components that would generate such a sound. To confirm the source, you must physically isolate the noise. While the camera is powered on, place your ear close to the power adapter plugged into the wall outlet. If the sound intensifies as you get closer to the brick and disappears as you move toward the camera mounting point, the adapter's internal capacitors or inductors are failing to dampen the vibration. While this is generally harmless to the device's circuitry, it indicates a component that is operating outside of its ideal tolerance.

How to Fix It

Since the power adapter is a sealed unit, it cannot be repaired internally. The only permanent solution is to replace the faulty power brick with a new unit that meets the exact voltage and amperage specifications of the Nest Cam Outdoor Wired.

1. Power down the system by unplugging the power adapter from the 120V AC wall outlet.
2. Carefully disconnect the weatherproof cable from the power adapter. Be mindful not to pull on the wires; instead, grip the plastic housing of the connector.
3. Inspect the pins on the connector for any signs of corrosion or oxidation. If you see green or white buildup, clean the contacts with a small amount of 90% isopropyl alcohol and a cotton swab.
4. Contact Google Nest Support to request a replacement power adapter. Provide them with the serial number found on the back of the camera or the bottom of the power brick to ensure you receive the correct revision of the hardware.
5. Once the replacement arrives, plug the adapter into the wall first, then connect the camera cable. Ensure the cable is seated firmly to prevent intermittent power cycles which can exacerbate electrical noise.

If That Didn't Work

• Test a Different Circuit: Plug the power adapter into a different wall outlet on a completely separate circuit breaker. Sometimes, "dirty power" or electrical interference from other high-draw appliances (like a refrigerator or HVAC unit) on the same circuit can induce a hum in sensitive power adapters.
• Remove Power Strips/Surge Protectors: If you are using a third-party surge protector or a cheap power strip, bypass it and plug the Nest adapter directly into the wall. Low-quality surge protectors can introduce voltage ripples that cause the adapter's coils to vibrate more aggressively.
• Check for Cable Interference: Ensure the Nest Cam power cable is not bundled tightly with other high-voltage electrical lines (such as 110V house wiring) inside the wall or along the siding. Electromagnetic interference (EMI) from nearby wires can occasionally cause an audible hum if the shielding in the cable is compromised.
• Perform a Factory Reset: While unlikely to fix a hardware buzz, a firmware glitch causing the camera to constantly reboot or "hunt" for a connection can cause the power adapter to fluctuate in power draw, creating a rhythmic buzzing. Hold the reset button on the back of the camera for 10-15 seconds until the status light pulses.

Heads Up

• Avoid Third-Party Adapters: Never use a generic 12V or 5V power brick from another device. The Nest Cam Outdoor Wired requires specific voltage regulation; using an incorrect adapter can fry the camera's mainboard instantly.
• Weatherproofing: When replacing the adapter, ensure the connection point remains dry. If the adapter is located outdoors, use a weatherproof electrical box to prevent moisture ingress, which can lead to electrical arcing and audible buzzing.
• Cable Tension: Do not pull the power cable taut across the mounting surface. Leave a small amount of slack (a "drip loop") before the cable enters the wall or the adapter to prevent tension on the internal copper wiring.