This International Standard provides guidance for measuring the steady-state root-meansquare (r.m.s.) values of quasi-static magnetic and electric fields which have a frequency content in the range 15 Hz to 9 kHz. Sources of quasi-static fields include devices that operate at power frequencies and produce power frequency and power frequency harmonic fields, as well as devices that produce fields independent of the power frequency. The magnitude ranges covered by this standard are 100 nT to 100 mT and 1 V/m to 50 kV/m for magnetic fields and electric fields, respectively. When measurements outside this range are performed, most of the provisions of this standard will still apply, but certain provisions such as specified uncertainty and calibration procedure may need modification. Specifically, this standard – defines terminology; – identifies requisite field meter specifications; – indicates methods of calibration; – defines requirements on instrumentation uncertainty; – describes general characteristics of fields; – surveys operational principles of instrumentation; – describes measurement methods that achieve defined goals pertaining to human exposure. Sources of uncertainty during calibration and measurements are also identified and guidance is provided on how they should be combined to determine total measurement uncertainty. In regard to electric field measurements, this standard considers only the measurement of the unperturbed electric field strength at a point in space (i.e. the electric field prior to the introduction of the field meter and operator) or on conducting surfaces. NOTE – Some separation between the normative measurement requirements in clauses 5 and 6 and the example measurement protocols and guidance for measurements in annexes D and E is unavoidable because of format requirements.