Health effects of magnetic fields during live-line maintenance

Abstract

Based on the latest researches and guidelines of International Commission on Non-Ionizing Radiation Protection (ICNIRP) extra-low frequency (ELF) electric and magnetic fields have several short-term and long-term health effects. The short-term effects of these fields is detectable, but the long-term effects are mostly unknown - results of epidemiological investigations are available only. Basically electric fields are determined by the voltage of an equipment and magnetic fields are generated by currents flowing through the conductors. In case of high voltage (HV) live-line maintenance (LLM) both high voltage levels and high currents could endanger the safety of the worker. Electric fields can be easily shielded by a conductive clothing based on the principle of the Faraday-cage, but only properly designed and manufactured clothing can guarantee the required efficiency. This principle of shielding electric fields is not effective against magnetic fields. Results of calculations, simulations and measurements prove that in some cases induced magnetic fields in the body of the live-line worker exceed the current limits defined by ICNIRP. This risk caused by the miss of the proper protection against magnetic fields endangers the safety of the workers and is unacceptable for any period of time during any live-line method.