In oil and gas installations, earthing systems play a crucial role in ensuring safety and mitigating risks associated with electrical faults and preventing hazardous incidents such as fires, explosions, and equipment damage due to static electricity buildup or lightning strikes.
Some functional earthing installations commonly used in Oil & Gas industry are:
- Equipotential Bonding
- This involves connecting all metallic structures and equipment within the facility to create an equipotential zone. This minimizes the risk of potential differences and reduces the likelihood of electrical hazards.
- Lightning Protection Systems
- Oil and gas facilities are often equipped with lightning protection systems to safeguard against lightning strikes. These systems include lightning rods, conductors, and grounding electrodes to safely dissipate the energy from lightning strikes.
- Substation Grounding
- Electrical substations within oil and gas installations require specific grounding systems to ensure the safe operation of high-voltage equipment. This typically involves grounding grids or mats installed beneath the substation to provide a low-impedance path to earth.
- Cathodic Protection
- In environments where corrosion is a concern, such as pipelines and storage tanks, cathodic protection systems are employed. These systems use sacrificial anodes or impressed current to protect metal structures from corrosion. Proper grounding is essential for the effective operation of these systems.
- Equipment Grounding
- All electrical equipment and machinery within the facility should be properly grounded to prevent electrical shocks and ensure the safe operation of the equipment.
These installations are designed and implemented in accordance with relevant industry standards and regulations to ensure the safety of personnel, equipment, and the environment in oil and gas installations.
Types of Earthing Systems
IEC 60364, also known as the International Electrotechnical Commission (IEC) standard for low-voltage electrical installations, provides guidelines for various aspects of electrical installations, including earthing systems. IEC 60364-4 provides five method of earthing which are abbreviated as TNC, TNS, TNCS, TT and IT. Three of these methods are most commonly applied to oil industry installations. The three common ones are TN, TT and IT.
Land-based installations
- The high voltage network is IT.
- The low voltage network is TT (or TNC or TNS) for four-wire systems.
- A motor feeder could be regarded as a TT system with neutral not present.
Offshore and marine installations.
- The high voltage network is IT.
- The low voltage network is TT due to the abundance of interconnected steelwork.
- A motor feeder could be regarded as a TT system with neutral not present.
