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 bet ween wire coding, magnetic fields and childhood cancer, although a more rec ent 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 som e uncertainty about the extent to which the UK medium-voltage electricity d istribution systems contribute to personal exposure and how this compares w ith US overhead supply systems. Studies on four different area types were c arried out to measure magnetic field intensities from typical electricity s upply utility substations and cabling in the vicinity of domestic housing. Typically at distances of two metres from the substations mean magnetic fie ld intensities were 20 nano teslas (nT) or less, increasing to 0.98 muT or less at the closest public access point. The mean magnetic field exposure l evel sampled around the four main test areas varied between 0.012 and 0.27 muT increasing to 0.30-0.80 muT at road junctions.