The methods of measurement detail the techniques and procedures for use when measuring fields on site near to an overhead line and also the techniques and procedures for making laboratory measurements of interference voltages and currents generated by line equipment and accessories. The procedures for determining limits define the expected values of radio noise field and the width of the "disturbed corridor" following the route of the line. This corridor takes into account the effective field strength of the wanted signal, the signal-to-noise ratio selected and the expected strength of the noise field for a given line. The procedures are valid only for long and medium waves.