A doorbell that is humming is a common problem that can be fixed easily because the button is used often; it can get partly stuck in the contact position or damaged.
The humming of a doorbell is not always dangerous however is the transformer gets excessively warm and the hummings start after previously running without humming, this could indicate there is excess loading due to sorted secondary windings of the transformer.
The humming of a transformer is caused by a magnetic field of the current that causes the thin metal laminations to vibrate and create the humming sound. A transformer that is shorted or overloaded will buzz and get very hot. It’s the 60Hz line frequency that makes the laminated steel plates rattle.
If you mount the transformer loosely to a junction box or a panel, this amplifies the noise.
If the doorbell is humming relentlessly, it is also possible that the button could be stuck in the contact position. When this happens, the bell or the chime unit won’t work even when the current is being delivered to it when you press the button. You have to disconnect it from its low voltage wires.
Can a Doorbell Cause a Fire?
If you are testing the voltages, the circuit should be on but if you are replacing any of the things on the doorbell, then make sure it is off. Even a 12 volt short can cause a fire as there could be something connected wrongly to the 120-volt line.
Doorbell Does Not Work but Hums
- Check the bell
- Check the chime or the bell units piston
- Check the wiring
- Check for a circuit breaker that is tripped
- Check if the transformer is burned out
- Make sure all of the wires are connected securely on the transformer bell and button
- Remove and check the button
- Reconnect the wires
Troubleshooting Why a Doorbell Might Hum
Tighten any loose screws in the chime hardware
As the humming and buzzing are caused by vibrations in the chime, it may be possible to reduce the vibrations by tightening any loose mounting screws. Just make sure to turn off the circuit breaker when you are working inside around the exposed wires.
Install the Doorbell Cam Chime Power Board
If the above does not solve, you may have to get a chime power board, like that of August doorbells. This device is installed on the chime and is designed to reduce humming significantly.
As mentioned above, doorbell humming is mostly caused by a stuck button or a faulty transformer. Once you have located the appropriate circuit breaker to kill power, back out the button from the wall and perform a visual inspection on the wires or the screws, a short circuit can also cause a hum; make sure they are tight and secure. Also, make sure that the button moves freely in or out. The button contacts may often become corroded or rusted over time, and they will have the tendency to stick. If there is any sign of corrosion, simply replace the button as they are not expensive.
If the problem is not a corroded or stuck button, the next item to test or replace is the transformer. This is because it can also fail over time, though not always but is also a possibility. You can get a replacement doorbell transformer at any improvement store.
The other problem could be within the wall-mounted chime unit. This is because the chime unit may fail over time, but it is the least common problem to expect with most doorbells. The stuck solenoid could be the only problem here.