Lightning protection systems and overcurrent protection

The lightning protection system is a system that protects the building against the dangerous effects of lightning discharges. The first lightning rod was installed in 1752 by Benjamin Franklin in Philadelphia.

Where does lightning come from

Water droplets and ice particles in a thundercloud rub against each other generating an electric charge (lód donates electrons to the water). When the charge is large enough (so the potential difference between the top of the cloud and the ground is sufficient) an electrostatic discharge occurs. During a lightning strike, a huge amount of energy is released, which can be very dangerous, both for electrical installations (all devices connected to the installation) and for human life. 

Lightning-protection principle of operation

The principle of operation of the lightning protection system is to intercept the discharges through the air-termination and, through the rest of the installation, safely transfer them to the ground. The coil is made of metal – usually aluminum, copper or stainless steel – thanks to which the lightning strikes it (the resistance of metal is lower than the resistance of air). A typical lightning protection system consists of:

• aów – elements that receive high-intensity electrostatic discharges (in the order of kiloamperes), which can be divided into natural air terminals (e.g. antenna masts, reinforced concrete reinforcements and other elements "naturally" protruding beyond the roof) and artificial ones (vertical bars or installations wrapper)
• drainóducts – elements connecting the air terminals with the earth electrode
• earthów – elements dissipating the energy of the discharge to the ground

Surge protectors

In the event of a lightning strike in close proximity to your home, a lightning protection system may not be sufficient. In this case, the currents that penetrate the network can ruin the devices connected to the installation. To protect yourself from the effects of such situations, use surge protection – use protectors and equipotential connections.

The protector is an element of the installation used to transfer the overvoltage current to the ground, thus protecting the devices connected to the network against the effects of these overvoltages. The protectors are divided into three classes marked with Roman numerals:

• class I – also known as B – protectors placed in the building connector
• class II – also known as C – surge protectors placed in the switchgear
• class III – also known as D – protectors placed directly on the device

In some cases (usually in single-family houses) arresters of class I+II (B+C) are used, which take up less space in the switchgear and do not require the use of additional decoupling chokes.

Knowledge of security may prove to be practical, but each time the construction of the installation should be commissioned to professionals who are licensed and comply with the standards.