Protective Grounding:

Protective grounding protects people and electrical equipment from overstrain and currents that can occur in case of an accident, misuse of equipment or lightning. Protective grounding is also used to protect equipment from ripples or breakages, especially when there are an instantaneous fluctuation in the grid and consumer chain as well as from electromagnetic signals from nearby equipment.

The main purposes of protective grounding are:

1.  Lightning protection grounding

2.  Grounding of pulsed surges

3.  Grounding of surges inside the grid

Such kind of groundings are constructed for electrical safety purposes (PU 1.7.29).

SPD - Surge Protection Device

SPD is designed to protect electrical equipment from accumulated charge in any part of the line / grid, which may result in:

• Electromagnetic fields (EMF);
• Powerful electrical equipment (or high voltage lines) nearby;
• Lightning struck nearby.

Before the installation, the SPD is installed in parallel with the electrical load to protect it from overvoltage.

Classic SPD is a gas damper, calculated for a certain limit of charge, which is less than the "safety range" of protected equipment. When this threshold is crossed, a charge occurs between the electrodes in the coil. As a result, the accumulated charge is transferred to the ground through the grounding.

Grounding is obligatory for both lightning rod and SPDs, as it is the grounding that carries out the discharging process, protecting the equipment from overloads above the permissible value on the line /grid.

Grounding Inside the Grid:

Another important function of grounding is to ensure the safety of humans and electrical equipment in case of an accident. The simplest example is the case of a short circuit of a phase wire in a power unit or water heater that passes through water. By touching such a device, a person will create an additional electrical circuit through which current will pass, causing damage to the internal organs of the body, especially to the nervous system and the heart.

To avoid such consequences, it is recommended to ground the equipment bodies. And the special protective electrical equipment are needed to turn off the power in emergency situations within milliseconds.

In our previous articles we spoke about the importance of technical materials in the plain language, so this material is also written in plain language, no complex calculations, schemes, or terminology is used.

The article was published in 30.07.2018.

Last updated in 20.06.2021.