In New York state, a church with brick cavity wall construction is hit by a lightening bolt, ignited, and gutted by fire before help can be summoned from the nearby village. In Illinois, a one story industrial plant is struck by a bolt which literally explodes a two story concrete block wall with brick facing. In Texas, a school janitor notices structural damage to a reinforced concrete wall near a lightning downed conductor following a severe weekend thunderstorm. Three common occurrences. So common, in fact, theat they have in the past largely taken for granted. But they need not be, says the Lightning Protection Institute, Chicago, for occurrences like them are easily and economically prevented by lightning protection systems for concrete and masonry low-rise buildings. Lightning protection consists of three major divisions: a roof system to intercept any bolt; a conducting system to carry the charge from roof to ground without damage to the structure; and a ground electrode system to harmlessly dissipate the lightning charge. A typical installation consists of these parts. The first is air terminals. Copper, or aluminum, 10 inches or higher, placed at a maximum of 20 feet apart on the high points of the roof and all projections, and sized, anchored and spotted. The second is the main conductors. These are special heavy copper or aluminum cable, interconnecting all air terminals, thus forming a closed loop on the roof, and leading to each ground electrode. In a concealed installation, the conductors may be run between the framing members of the roof, within the cavity of a double brick wall or within a placed concrete wall if desired. The third is the branch conductors. These are lengths of lightning conductor cable which connect into the main conductor system all major metal bodies not other wise properly interconnected, and which are within 6 feet or any conductor. Finally is the grounding. For small buildings on moist, tight soil, at least two one-half inch or larger diameter copper clad cords sunk to a minimum of 10 feet are required. For larger buildings, additional ground rods are required. Special counterpoise grounding systems may be needed where soil is high-resistance- sandy, rocky, arid.