BASIC LIGHTNING - Lightning Protection


Lightning voltages and currents (up to 200kA) are very high and do cause damage to buildings and electrical or electronic equipment.

Direct Strike: is when lightning strikes a building resulting in mechanical and structural damage. Protection against direct strike lightning is achieved by installing an air termination system, comprising finials and ridge conductor and an earthing system. A direct strike may also result in induced over voltages to power cables, telephone lines, data lines, resulting in damage to electronics, TV's, computers data lines, electrical equipment etc. Surge protection devices (SPD) need to be installed for protection.

Indirect Strike: is when lightning may strike “in the area”- the power lines, the ground, the telephone lines, causing surges in the building’s power supply, telephone and/or data lines resulting in damage to electronic equipment, computers, TV's, telephones etc. Surge protection devices need to be installed in the power supply and cable link systems for protection. 


The information covered in this document is intended to be a practical guide
for basic design and installation of a Lightning Protection System (LPS).

1 - Capture the lightning at a desired point on a building/structure.
2 - Conduct this lightning energy safely to earth.
3 - Provide safety to human life and protection to business systems.

The IEC issued a set of Standards in 4 Parts (IEC62305-1, -2, -3 & -4) that
comprehensively covers:
General Principles (-1),
Risk Management (-2),
Physical Damage to Structures and Life Hazards (-3) and
Electrical and Electronic Systems within Structures (-4).



The IEC 62305 came into force in September 2006 and consists of four parts.
South Africa has issued a front end standard SANS 10313 that is used in conjunction with the IEC Standards.

IEC 62305-1 Part 1 General Principles
Introduction to the other Parts of the Standards.

IEC 62305-2 Part 2 Risk Management
This part specifically deals with making a risk assessment, the results of which define the level of lightning protection system (LPS) required.

IEC 62305-3 Part 3 Physical Damage to Structures and Life Hazards
This part gives guidance on the classification of an LPS and maintenance and inspection programmes.

IEC 62305-4 Part 4 Electrical and Electronic Systems within Structures
This part looks at the electrical and electronic systems and includes a risk assessment that is separate from the structural assessment.

SANS 10313 Front End Standard, covers issues specific to South Africa for Protection against Lightning Physical Damage to Structures and Life Hazards.

The following pages address the salient points from these standards and is a practical guide for installers of lightning protection systems.


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