The contribution of local distribution substations and associated area distribution system to personal exposure to power frequency magnetic fields

A number of epidemiological studies has shown a significant correlation between wire coding, magnetic fields and childhood cancer, although a more recent study has not [McBride et al. (1999) Am. J. Epidemiol. 149 (9), 831-842]. In the UK there is currently no equivalent to wire-codes and there is some uncertainty about the extent to which the UK medium-voltage electricity distribution systems contribute to personal exposure and how this compares with US overhead supply systems. Studies on four different area types were carried out to measure magnetic field intensities from typical electricity supply utility substations and cabling in the vicinity of domestic housing. Typically at distances of two metres from the substations mean magnetic field intensities were 20 nano teslas (nT) or less, increasing to 0.98 T or less at the closest public access point. The mean magnetic field exposure level sampled around the four main test areas varied between 0.012 and 0.27 T increasing to 0.30-0.80 T at road junctions.