This part of IEC 62271 gives practical guidance for the evaluation and documentation of the external electromagnetic fields which are generated by HV switchgear assemblies and HV/LV prefabricated substations. Basic requirements to measure or calculate the electric and magnetic fields are summarised for switchgear assemblies covered by IEC 62271-200 and IEC 62271-201, and for prefabricated substations covered by IEC 62271-202. NOTE 1 The methods described in this technical report refer to three-phase equipment. However, the methodology may be used correspondingly for any single- or multi-phase equipment covered by this technical report. This technical report applies to equipment rated for voltages up to and including 52 kV and power-frequencies from 15 Hz to 60 Hz. The electromagnetic fields which are generated by harmonics or transients are not considered in this technical report. However, the methods described are equally applicable to the harmonic fields of the power frequency. Detailed generic information on requirements and measurements of low-frequency electromagnetic fields is given in IEC 61786. This technical report covers evaluation under factory or laboratory conditions before installation. The electric and the magnetic fields can be evaluated either by measurements or by calculations. NOTE 2 Where practicable, the methods described in this technical report may also be used for installations on site. It is not within the scope of this technical report to specify limit values of electromagnetic fields or methods for the assessment of human exposure.