Grounding Systems

Grounding systems have three main goals: ensuring the safety of people and equipment, maintaining stable voltage levels, and improving the performance of electrical systems while also providing protection for them.

Types of Grounding

System grounding, equipment grounding, and human grounding are the three primary types of grounding systems that can be distinguished apart from one another.

System Grounding:

• Purpose: The purpose of system grounding is to establish a connection between the neutral point of an electrical system, like the neutral of a transformer or generator, and the ground. This sort of grounding not only enables the establishment of a reference voltage for the system but also facilitates the identification and isolation of problem areas.
• Function: The function of system grounding is to stabilize the voltage levels inside the electrical system and to assist in the efficient operation of safety devices. This guarantees a straight path for fault currents to the earth, allowing for quick fault isolation.
• Example: An example of this would be connecting the neutral point of a power transformer to a grounding electrode. This connection ensures that any fault current is securely sent to the ground.

Equipment Grounding:

• Purpose: The objective of equipment grounding is to establish a connection between the ground and the metal components of electrical equipment that do not transport current. These components include conduits, frames, and enclosures, respectively. An electric shock can be avoided by using this method of grounding, which ensures that these components continue to have the same potential as the earth.
• Function: In terms of its function, equipment grounding serves the purpose of facilitating the flow of fault currents to the earth, thereby ensuring that exposed metal components do not reach potentially hazardous voltage levels. Those individuals who might come into contact with these components are safeguarded by it.
• Example: There is a connection made between the metal enclosure of an electrical panel and a grounding conductor. This connection ensures that the metal enclosure is at the same potential as the ground.

Personnel Grounding:

• Purpose: Personnel grounding's primary goal is to protect humans from electric shocks by ensuring that they do not become part of the electrical circuit. In order to discharge static energy in a secure manner, this sort of grounding entails the utilization of grounding mats, wrist straps, and other appropriate gear.
• Function: The function of personnel grounding is to prevent the accumulation of static charges on individuals, hence lowering the risk of electric shock and damage to electronic components that are sensitive.
• Example: For instance, workers use wrist straps connected to grounding points to safely discharge static electricity in environments where it poses a risk.

Figure 2: Grounded wrist strap

Grounding Principles and Standards

National Electrical Code (NEC)

The National Fire Protection Association (NFPA) in the United States issues the National Electrical Code (NEC) as the standard for the safe design, installation, and inspection of electrical systems. The National Electrical Code (NEC) provides comprehensive rules on grounding techniques to ensure the security and efficiency of electrical systems.

Purpose and Scope: The purpose of the National Electrical Code (NEC) is to protect persons and property from the perils of electrical hazards. The requirements for grounding that are necessary for a wide variety of systems and pieces of equipment are included in this comprehensive coverage of electrical installations.

System Grounding: The National Electrical Code (NEC) specifies the standards for grounding electrical systems, which include service grounding, separately derived systems, and the installation of equipment enclosures that are grounded. Among the most important provisions are:

• Grounding Electrode System: The National Electrical Code (NEC) provides a list of approved grounding electrodes, which include ground rods, plates, and concrete-encased electrodes. Additionally, the NEC specifies the installation standards for these grounding electrodes with the aim of ensuring a low-resistance path to the earth.
• Grounding Electrode Conductor: The guidelines for sizing and installing conductors that connect the electrical system to the grounding electrode are referred to as the grounding electrode conductor. These guidelines ensure that the conductors offer sufficient capacity to carry fault currents.

Equipment Grounding: The National Electrical Code (NEC) outlines in great depth the standards that must be completed in order to ground non-current-carrying metal components of electrical equipment, such as conduit systems and enclosures. To ensure that these components do not become dangerous in the event of a malfunction, this measure is taken.

Bonding: Bonding is the process of electrically connecting all exposed conductive parts and the grounding system. The purpose of bonding is to ensure that fault currents have a path that is both continuous and efficiently effective. In order to eliminate potentially hazardous voltage fluctuations between conductive elements, the National Electrical Code (NEC) mandates bonding procedures and materials.

Periodic Updates: The National Electrical Code (NEC) undergoes periodic updates every three years in order to include new technologies, address growing safety issues, and refine current requirements. In order to guarantee compliance and safety, the professionals involved in electrical work must be up to speed with these modifications.

Organizations such as the International Electrotechnical Commission (IEC) and the Institute of Electrical and Electronics Engineers (IEEE) are responsible for the development of international standards for grounding. These guidelines offer a universal foundation for grounding techniques, which guarantees uniformity and safety in electrical installations all across the world.

International Electrotechnical Commission (IEC) Standards

IEC 60364: The International Electrotechnical Commission (IEC) 60364 provides a thorough set of guidelines for electrical installations, including grounding and bonding standards. Additionally, it discusses the selection of grounding electrodes and conductors, as well as the system's earthing and safety measures.

• Earthing Systems: The International Electrotechnical Commission (IEC) 60364 provides a definition of many earthing systems, including TN, TT, and IT systems. Each of these systems has its own unique grounding configurations and safety precautions. The adaptability of these systems allows their use in a wide variety of situations and installations.
• Protective Measures: The standard provides a comprehensive outline of protective measures that are designed to safeguard electrical systems from electric shock, overvoltage, and electromagnetic interference. These procedures are designed to ensure the safety and dependability of electrical systems.

iii. Institute of Electrical and Electronics Engineers (IEEE) Standards

IEEE 80: This is primarily concerned with grounding techniques for substations. It offers comprehensive suggestions for the design, installation, and maintenance of grounding systems in high-voltage situations. There are a variety of issues that are covered, including step and touch potential, grounding grid design, and soil resistivity measurements.

IEEE 142 (Green Book): This is a standard that provides principles intended for grounding electrical systems in commercial and industrial settings. Additionally, it addresses the mitigation of ground potential rise (GPR) and transient overvoltages, as well as the design of grounding systems and the grounding of specific pieces of equipment.

Although the purpose of international standards is to create a framework that is uniform, they also allow for adaptability to the conditions and legislation that are specific to a given location. Professionals in the electrical industry must understand these standards and incorporate them into area codes and practices.