The risk from lightning to different objects and living beings, as well as the possibility of reducing this risk, are considered in this chapter. To do this in unequivocal way, the terms involved will first be properly defined.
First, the distinction between an object and a structure or a service should be clarified. The term ‘object’ covers both the structure and the external services [1]. The term ‘structure’ is reserved for a building and its internal equipment, in particular its electrical and electronic systems, and for those people within it and its external areas. The term ‘service’ is reserved for the different kinds of external installations or systems (mains, electronics, informatics and telecommunications systems, water and gas piping) connected to a structure for which a lightning hazard is considered.
Similarly we will distinguish between the terms ‘lightning flash’, ‘lightning strike’ and ‘lightning stroke’ [2]: