The practical application of limb contact current limits in the safety programme at electromagnetically exposed workplace

The international guidelines (including European Directive 2013/35/EU) set out limits for limb contact currents in the frequency up to 110 MHz, in order to protect workers against the indirect effects of exposure to electromagnetic field. The aim of the study was to analyse the practical role of that kind of metric for an evaluation of the electromagnetic hazards at the workplace. For the practical application of limb contact current limits, the practical limitations need to be considered in their in-situ evaluation by measurements, such as the uncertainty of the level of contact current related hazards of at least +/-50% (covering inter-person variability, the influence of the contact and exposure conditions and the calibration of measurement devices). Additionally, with respect to bioethical rules, such an evaluation in routine occupational safety practice needs the use of phantoms (e.g. equivalent circuits) replacing the human body in the measurement circuits - which increases the uncertainty of the evaluation. The next important limitation is caused by inter-person variability in sensitivity to limb currents, which mean that some percentage of workers are sensitive to limb current flow at levels significantly lower than their relevant limits. Considering such practical problems, the management of contact current related hazards should be based on the implementation of sufficient protection measures where a high exposure level at the workplace is identified by electric or magnetic field measurements, avoiding individual tests of contact current levels.