Cover & sound-suppression for doorbell transformer in utility closet

Question

This transformer is installed in the utility closet of a 1970's condo.

Notice the wad of cut paper sheets pinched between transformer and the wall plate. This is an attempt at halting a low-tone humming caused by the transformer. Is there a better way to avoid this annoying hum?

And should a transformer be exposed in the open like this? If this is proper, are there covers available to hide the ugly and protect the wires?

Answer 1

The best way to eliminate transformer noise is to purchase a quality transformer. The noise is because the laminated core is heavily loaded or overloaded and the plates are actually vibrating because of eddy currents. I can’t quite make out the size, but it looks like 24V, 20VA. I would bump it up to a 24V, 40VA unit that would be compatible with video doorbells and probably a lot quieter. Usually, hard mounting is fine unless the core is coming apart or overloaded so going to a new larger one fixes both problems.

Answer 2

First, even though the exposed wires are low-voltage, likely 16 VAC, they should be covered for esthetics (if the transformer were accessible to children, not inside a closet, it is likely required). That said, the buzzing noise is likely being transmitted to the metal plate and wall, which make it much louder. A few things to reduce the buzz:

• Remove the transformer from the metal plate and reinstall it using rubber grommets in the mounting holes of the transformer and of the cover plate, but run a ground wire from the box to a mounting lug of the transformer. This would also reduce vibration of the plate cause by the transformers magnetic field, effectively making the plate act as a loudspeaker.
• Put sound-deadening tape inside the metal box cover. Perhaps a local garage has a small left=over piece? Golf-club weighting tape might also work.
• Install a replacement of the correct voltage and current or VA rating, in the hope it would be quieter. A similar transformer might be ~US$10.