Lightning protection-General introduction

1. General introduction

Lightning is a naturally occurring spark discharge or short-lived electric arc. Lightning discharges can take place from one cloud to another, or between a cloud and the ground. Lightning - one of the "electrometeors" - generally occurs during thunderstorms, where it is accompanied by thunder. Lightning involves an ex-change of electric charges (electrons or gas ions), in other words, electric currents flow. Depending on the polarity of the electrostatic charge, lightning can alternatively start from the ground.
Some 90% of all lightning discharges between a cloud and the ground are negative ground-to-cloud strikes. Here, the lightning begins in an area of negative charge in the cloud and spreads to the positively charged ground.

However, the vast majority of discharges take place within clouds, or from one cloud to another.
NASA has measured the annual global frequency of lightning over the period 1995 to 2003. The local values obtained by NASA can be used to determine the annual number of lightning strikes per km² even for countries that do not have their own information on numbers of lightning impulses. For risk assessments according to IEC 62305-2, it is recommended that these values are doubled.

The less common types of discharge are:
• Negative ground-to-cloud lightning
• Positive cloud-to-ground lightning
• Positive ground-to-cloud lightning

1.General introduction

1.1 Lightning

1.1.1 How lightning is formed

1.1.1.1 Types of thunderstorm

1.1.1.2 Charge separation

1.1.1.3 Charge dispersion

1.2 Risks Posed by lightning discharges

1.2.1 Risk to humans

1.2.2 Risk to buildings and equipment

1.2.2.1 Transient surges

1.2.2.2 Lightning surges

1.2.2.3 Effects of surges

1.3 Sources and causes of damage according to standards

1.4 Test currents and simulated surge voltages 

1.5 Legal regulations defining what lightning protection standards

1.5.1 Lightning and surge protection standards

1.5.2 Hierarchy of standards: international/European/national

1.5.3 Latest German national lightning protection standards

1.5.4 Responsibility of the erection engineer

1.5.5 Responsibility of the operator

1.6 Financial implications of lightning and surge voltage damage

1.7 lightning protection risk analysis and categorisation by lightning protection class

1.7.1 frequency of lightning stikes by region

1.7.2 equivalent interception area

1.7.3 estimation of the damage risk

1.7.4 empirical lightning protection classification of buildings

1.7.5 cost-effectiveness calculation for lightning protection systems

1.7.5.1 costs without lightning protection system

1.7.5.2 costs with lightning protection system

1.7.5.3 comparing the costs of lightning damage in buildings with and without a lightning protection system

1.8 laboratory testing of lightning and surge protection componentys