Finding out more: Audible noise


There are three basic sources of noise from substations, with different characteristics.

  • Transformer noise is a practically constant low-frequency hum. Transformers generally run continuously except for maintenance.
  • Switchgear noise is generated by the operation of circuit breakers and is “impulsive” in character - it is loud but of short duration.
  • Substation auxiliary plant such as diesel generators and air compressors may also contribute to the noise.

Overhead Lines

High-voltage power lines can generate noise under certain conditions.

  • Audible noise from overhead-line conductors and fittings is generally either a “crackle” or a “hum”. It occurs mainly in wet weather, particularly fog and rain.
  • Noise may also arise as a result of the wind blowing past the line or pylons.

What to do about noise issues

If you have concerns about audible noise, contact the electricity company which owns the equipment - National Grid or the relevant Distribution Network Operator.

For noise from the operation of a National Grid overhead line or substation, contact 

More information is available on the National Grid website.