Mitigating transformer hum

Transformers are everywhere. They can be found in our electrical equipment at work, at home, and during our leisure time. Wherever we use electricity, there will be a transformer. Transformers change electricity from one voltage to another. They reduce the voltage to make it safe to use in hairdryers or refrigerators, and they increase the voltage to reduce power loss.

Mitigating transformer hum

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Most of the time, we don’t even know that a transformer is there, and we certainly don’t think about them. They are in all our electrical control components, after all. However, there’s one time that we really do notice them, and that’s when they hum.

Why do transformers make that noise?

The humming noise that we hear all too often is a sign that the transformer is working. Even though there are no moving parts in a transformer, the hum is a result of the electrical activity. It’s caused by “magnetostriction”.

A transformer works by passing an electric current through wires wrapped around a magnetic core. Basically, the magnetic current that passes through the coils of the transformer makes changes in the dimensions of the ferromagnetic coils. This causes vibration and leads to humming.

In addition, air currents can increase the vibration, and some transformers are fitted with fans that make a noise. The noise from the vibration can also be transmitted or even increased by materials surrounding the transformer, the housing of the transformer, or the base that it rests on. For a fuller explanation of transformer noise, check out these articles. ( and (

How can we reduce the noise?

Some people might find the hum soothing, but most of us will find it mildly annoying. In some situations, such as medical equipment, it’s a real problem. Thankfully, there are ways of mitigating this noise.

First, you should make sure that your transformer is fitted as firmly and securely as possible to minimise vibration noise from the surfaces the transformer rests on. A good retailer such as osmelectrical should be able to advise you on the right kind of fixings and frames.

Second, consider using vibration pads or isolation mounts underneath the transformer to dampen the vibrations further. You can also insulate the surroundings. Acoustical-absorbing material is available to cover reflective surfaces that might otherwise transmit, reflect or amplify the sound.