Step Potential- The difference in surface potential experienced by a person bridging a distance of 1m with the feet without contacting any grounded object.

 

Touch Potential- The potential difference between the ground potential rise (GPR) and the surface potential at the point where a person is standing while at the same time having a hand in contact with a grounded structure.

 

Soil Resistivity- The unit of resistivity is the ohm meter (Ω.m). This corresponds to the theoretical resistance in ohms of a cylinder of soil 1m² cross-section and 1m long.

 

Methods for testing Earth Resistance (existing electrodes)

 

Fall of Potential Method

61.8% method

Clamp On test method

 

Methods for testing Soil Resistivity (no earth grid)

 

Wenner 4 pole method

Schlumberger method