Earth Testing or “Earthing” is an integral and important component of any power system and lighting protection systems. Earth testing is performed to ensure the earth ground resistivity is at a low, compliant level.

Overtime, earthing resistivity levels can increase and earthing rods and connections can deteriorate. Factors that vary the earthing resistivity can be corrosive soils, soil type, temperature variations and high salt content.

Whether soil is largely clay or very sandy, for example, can change the earth resistivity a great deal, compared to other soils such as lime stone or gravel.


Two facts lead to the effects of temperature of earthing resistivity. One, water content in soil mostly determines earthing resistivity. Two, an increase in temperature markedly decrease the water resistivity.

In soil, conduction of current is largely electrolytic. Therefore, the amount of moisture and salt content of soil radically affects its resistivity.

Preventative Electrical Services will ensure the appropriate testing is conducted, ensuring bonding, earth grids and systems are at the same potential difference and perform to their specification.