Earth Grid Testing
Testing of an earthing system is important to ensure that earthing installations have not changed over time. An earthing system is designed either as a standalone installation or as part of a larger integrated system. Either way routine checking of its resistance is critical to the fundamental operation of the entire electrical system.
All testing is performed in accordance with IEEE Standard 81.
The “Fall of Potential Method” is the test method used to perform a simply test to determine the resistance of an earthing system.
Other important aspects of checking the integrity of an earthing system are;
· Visual inspections,
· Continuity testing,
· Loop impedance testing,
· System alterations that may affect the designed performance of the earthing system.
If an earthing system is being commissioned for the first time or after augmentation, changes or been damaged, then it is recommended that a Current Injection Test be performed to determine the full functional characteristics of the earthing system. This includes measurements for touch & step potential, transfer voltages, earth optional rise and ensuring compliance to safety criteria. Large earthing system should also be tested every 5-10 years to ensure its integrity.