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Earthing Audit

Earthing Audit for Grounding System

EARTHING HEALTH ASSESSMENT

JEF Earthing System Health Assessment ensures the healthiness of the complete Earthing system. The earthing system must be inspected periodically to ensure health and effectiveness. Since the majority of Earthing System is buried underground/inaccessible, it suffers from “OUT OF SIGHT IS OUT OF MIND” syndrome. Unseen Components like Equipment Earth Conductor (Strip), Earth Grids / Mats which are buried or inaccessible, tend to be taken for granted or ignored, though they are crucial.

As per CEA regulation 41 (xv) b, the resistance of earthing system shall be maintained as low as possible such that sufficiently large fault current flows in the circuit and the breaker trips ON TIME to isolate the faulty circuit.

A Complete Earthing System with all its components- Equipment Earth Conductor, Earth Electrode, and Earth Grid / Mat should offer a low resistance path for fault current to flow so that breakers trip on time to prevent accidents such as -Fire, Short Circuit, and Electric Shock and so on.

Earthing Health Assessment Audit Overview

Application Area: AIS & GIS Substations, Commercial Buildings, Retails outlets, Warehouses, Data Center's, Factories, Manufacturing Plants, Oil & Gas, Metro rail, Process plants, Wind & Solar Plants, Tank farms, Critical structures like communication towers, power plants and more.

Reference Standards: IEEE 81-2012 | IEE Regulation | CEA regulations for measures relating to safety and electric supply - 2021 (Draft) | IEEE 80 – 2013 | IS 3043 | BS 7430 | CBIP manual-339

Why Earthing Health Assessment Audit?

  • Earthing Health Assessment Audit is needed because earthing deteriorates over time due to various reasons such as Chemical Properties of Soil leading to Environmental Corrosion, Thermal & Electrical Stress on joints due to Electrical Faults, Galvanic Corrosion in some cases and Improper Workmanship.
  • Normally Earth Electrode (Pit) Resistance alone is measured periodically. Electrical System is deemed safe with a low Earth Electrode Resistance.
  • The Integrity of the Earth Conductor (Strip) between the Earth Electrode and Equipment is rarely checked. Hence, Breaker may not trip even if Earth Electrode Resistance is low.
  • In reality, timely operation of the breaker (Electrical Safety) depends on the resistance of earth loop formed by equipment the earth conductor (Strip), earth electrode and phase conductor.
  • System modifications and Deterioration of Earthing system can render the original design calculations of protection systems (breakers) invalid.
  • JEF’s assessment methodology covers this crucial gap by checking all the above parameters, thereby ensuring timely operation of the breakers to prevent accidents/damage.
  • Carried out on live systems without shut down using sophisticated meters and practices. By emphasizing and encouraging the use of the right personal protection equipment.
  • Design risk mitigation/ management measures to enhance safety

Value Adds from JEF

  • Cost-effective solution to overcome the hazards and mitigate risks.
  • Pin point open or weak joints in a buried earthing grid, which can severely affect safety and cause the unexplained failure of equipment.
  • Identifies locations with unsafe touch & step potentials in the substation.
  • Ensures timely tripping of breakers in case of a fault, thus preventing short circuits, fire, shocks and so on.
  • Ensures Human and Equipment Safety.
  • Site Survey and measurements from qualified and experienced Engineers.
  • Recommendations by experts based on a detailed site survey.
  • Recommendations ensure compliance with the latest Indian and International Standards.
  • Detailed report with measured data, anomalies & defects observations, recommendations for rectification along with site photographs.

• Majority of faults in the system are phase to ground.
• Majority of earthing system is below the ground.

• Failure of Electronic Cards & Equipment.
• Failure of ELV assets.
• Maloperation of Ground Fault Protection.
• System Derating due to Power Quality Issues.
• Neutral Voltage shift due to rise in Neutral to Ground Voltages.
• Noise Interferences Resulting in Nuisance Tripping.
• Risk to human life.

• Grounding Audit is not just the measurement of resistance.
• Resistance measurement may not give holistic view of the condition of earthing system.
• Ground grid has multiple parallel paths, few open risers/ groundconnections/ grid disconnections will not impact the overall resistance.

• Reduction in equipment failures by about 38-40%.
• Enhanced reliability of equipment.
• Reduces nuisance tripping.
• Improves human safety.

• Pinpoint open and defective risers.
Corrective action - excavate that specific point and rectify.
• Identify specific areas of Grid Islanding (Intra Grid)
Corrective action - provide alternate connections.
• Identify grids which are not connected (Inter Grid)
Corrective action - provide alternate connections.

ACTIVITY

• Soil Resistivity Test.
• Earth Electrode Resistance Test.
• Riser Integrity Test.
• Grid Integrity Test.
• Effect of Corrosion.
• Touch and Step Potential Test.
• Modelling and Simulation of earth grids for safe touch & step potentials.

ACTIVITY

• Soil Resistivity Test.
• Earth Electrode Resistance Test.
• Earth Loop Impedance Test.
• Prospective Fault Current Test.
• Riser Integrity Test.
• Effect of Corrosion.