PROTECTION OF GROUND SPACE FACILITIES FROM THE EFFECTS OF LIGHTNING 700933

Aerospace and ground facilities are often both extensive in area and located in regions of high lightning activity. While the hazards of fire, explosion, and electrocution caused by direct lightning strokes are generally well recognized, the indirect effects of lightning on electrical and electronic systems are less well recognized. Electronic systems can often be damaged even by lightning strokes that do not hit the buildings or electrical wiring directly. The lightning hazards to electronic systems are often compounded by shielding and grounding practices used for control of lower frequency electromagnetic interference. These shielding and grounding practices are sometimes diametrically opposite to those that should be employed for control of lightning effects. This paper first describes the conflicts, real and apparent, between the grounding and shielding requirements for control of lightning and EMI. It discusses some ways to resolve these conflicts and draws upon a case history to illustrate the points raised.