Protecting a distributed data acquisition system from lightning

In 1983 AECL Research installed a hydrogeological monitoring system at its underground research laboratory (URL) site to record water levels in about 40 boreholes spread over an area 1.5 km by 2.5 km. A major concern in designing this system was to make it resistant to damage from lightning. Other systems, installed over much smaller areas, were frequently damaged by lightning, even though pickup from the power line was often eliminated by using battery or generator power. The system described is line-powered and achieves resistance to lightning through the following measures: surge protectors, filters and ultraisolation transformers installed on connections to the power line, and surge protectors installed at each end of the lines transmitting analog and digital signals over long distances. These measures have not completely eliminated damage from lightning, but have kept it within acceptable limits and are probably all that can be done with existing technology.<>