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  • Noise

  • High voltage overhead lines and certain items of substation equipment can generate noise. With lines, the level of this noise depends on the voltage. Sometimes a ‘crackling’ sound accompanied by a low frequency hum can be heard.

    Noise from an overhead power line is produced by a phenomenon known as ‘corona discharge’. Overhead lines are built to minimise this, but surface irregularities caused by damage, insects, raindrops or pollution may locally enhance the electric field strength sufficient for corona discharges to occur.

    The noise levels associated with an overhead power line are weather related – higher noise levels are likely to occur:

    •during damp weather conditions
    •during long dry spells when airborne debris sticks to the lines (but this is washed away by a heavy rain shower)
    Where complaints about noise arise from our works, National Grid will investigate the cause of the noise and, if our equipment or practices are at fault, do all that we reasonably can to minimise the noise level.

    We undertake research into lower noise alternatives that can be used when installing or refurbishing equipment. Where practicable, we will deploy new techniques or equipment which produce less noise.