What is Grounding? Types, Standards, Soil Resistance, and Application Guide

Safety in electrical installations is ensured not only by selecting the right materials but also by grounding the system in accordance with international standards. Grounding is one of the most critical components of electrical installations, both for life safety and equipment protection. In this guide, we will discuss what grounding is, why it is done, its types, standards, earth resistance measurement, and basic application steps in detail from an engineering perspective.

What is grounding?

Grounding is a safety practice that ensures leakage current in electrical systems is transferred to the ground in a controlled manner , following the path of lowest resistance. A properly designed grounding system protects people from electric shock, prevents damage to equipment, and ensures the safe operation of the facility.

To put it in international terms; according to the TS EN 60364-5-54 standard, grounding is the direct connection of inactive metal surfaces or the neutral point to the earth via a conductor with electrical continuity.

Why is grounding done?

Without proper grounding, electrical faults can directly damage equipment, facilities, and most importantly, people. A healthy grounding system significantly reduces the following risks:

• Reducing the risk of electric shock: Leakage currents flow through the ground, not through the human body.
• Eliminating voltage imbalances: This prevents damage to devices in cases such as neutral wire breakage or phase imbalance.
• Equipment and facility protection: Devices that experience body voltage are made safe thanks to grounding.
• Lightning protection: Lightning strikes and sudden voltage surges are channeled into the ground in a controlled manner.
• Operational continuity: Failures are localized, preventing the entire plant from shutting down.

What are the different types of grounding?

Grounding applications can be examined under three main headings according to their purpose and facility structure: protective grounding , operational grounding , and lightning grounding .

Protective Earthing

Protective grounding is the process of connecting inactive metal surfaces (device housings, panel casings, metal pipes, etc.) in electrical installations to the ground. Its primary purpose is to protect people from electric shock .

Application examples:

• Ground terminals of power outlets and end-user devices
• Grounding of machines such as motors, pumps, and fans.
• Grounding of panels, cabinets and metal enclosures.
• Outdoor lighting poles and metal structures

Industrial Grounding

Operational grounding is the process of connecting the neutral point or certain circuit components of an electrical system to the ground under normal operating conditions, as required by the system's operating principles. The aim is to ensure the stable and safe operation of the system.

Application examples:

• Transformer star point (neutral) grounding
• Generator neutral grounding
• Star point grounding in medium voltage systems.

Lightning Grounding

Lightning grounding is a system in lightning protection systems (LPS) that ensures the safe transmission of high-energy current from the catcher terminals and down conductors to the ground. The TS EN 62305 standard defines the design criteria for these systems.

Lightning grounding protects buildings and facilities from mechanical damage, fire, overvoltages, and electronic equipment damage that may be caused by lightning.

How to do grounding?

Grounding applications are not simply a matter of driving a rod into the ground. Soil properties, resistivity, electrode depth, conductor cross-section, connection techniques, and regulatory requirements must all be considered together. Below you will find the basic steps of a professional grounding application.

1) Ground Measurement and Design

A sound grounding design first requires measuring the resistivity (ρ) of the soil. The most common method for this is the Wenner four-electrode method .

ρ = 2 · π · a · R

• ρ : Soil resistivity (Ω·m)
• a : Distance between electrodes (m)
• R : Measured resistance (Ω)

Approximate specific resistance ranges according to sample soil types:

2) Placement of Grounding Electrodes

The most commonly used electrodes are copper-clad steel rods and galvanized strip plates. The placement of the electrodes is determined according to the specific resistance of the ground and the desired grounding resistance.

• Rod electrodes are generally used in lengths such as 1 m, 3 m, or 6 m.
• The electrode head should remain approximately 30–40 cm below the ground to protect it from frost and external influences.
• If the desired resistance cannot be achieved, multiple electrodes are used in a star, ring, or mesh arrangement.

The location of the grounding electrode should be chosen as close as possible to the building foundation and as far away from underground utilities (water, sewage, natural gas, etc.) for safety reasons.

3) Basic Grounding Application

One of the most reliable methods for newly constructed buildings is foundation grounding . According to TS EN 50522 and related regulations, a continuous loop is formed by laying galvanized strips inside the concrete foundation.

• Galvanized strips (e.g., 30×3 mm, 25×4 mm) are laid along the raft foundation or foundation beams.
• Electrical continuity of reinforced concrete reinforcement is ensured.
• Riser terminals are left for connection to the outside of the foundation and are connected to the external grounding system.

Thanks to foundation grounding, a grounding system with a large surface area and low resistance is obtained between the building and the ground. You can find more technical details about this application in Esco Elektrik's foundation grounding strip usage guide.

4) Connecting the Grounding Conductors

Copper, galvanized strip, or copper stranded bar are preferred conductive materials for grounding conductors. The robustness and corrosion resistance of the connection points are critical for the longevity of the system.

• Exothermic welding: Provides a permanent bond at the molecular level between grounding rods, strips, and conductors. It is the most reliable solution against corrosion.
• Bolt and clamp connections: Easy to install, but require regular maintenance to withstand outdoor conditions.
• Connection busbars: Used to connect different branches of the grounding system to a single point.

Thermowelded connections are preferred, especially in critical facilities and outdoor applications. Esco Elektrik's grounding stake and plate selection guide will help you choose the right materials.

5) Grounding Resistance Measurement

After the grounding installation is completed, the grounding resistance of the system must be measured . For this measurement, special devices (ground meggers) using the 3-pole (3P) or 4-pole (4P) method are generally preferred.

Generally accepted target resistance values:

Measurement results must be recorded and repeated at regular intervals (usually at least once a year in industrial facilities).

6) Periodic Inspections and Maintenance

Grounding systems can experience performance degradation over time due to corrosion, changes in soil structure, and mechanical impacts. Therefore:

• In industrial facilities, once a year,
• Lightning protection systems should be inspected at least once a year.
• More frequent intervals in hazardous environments (explosive environments, etc.)

Measurement and visual inspection are recommended. Connection points, thermowelds, strips, and rods should be inspected periodically and replaced if necessary.

Points to Consider When Performing Grounding

• Grounding electrodes must be at a safe distance from underground water, sewage, natural gas, and similar networks.
• In very stony, dry sand, or rocky terrain, it is difficult to achieve low resistance with a single rod; a multi-electrode and ring system should be preferred.
• Soil conductivity directly affects system performance; low-resistance soils should be preferred.
• The joints should be free of looseness or oxidation; thermowelding should be used if possible.
• Measurements must be taken after installation, and systems that exceed the target value should not be put into operation.

How to Reduce Grounding Resistance?

The following methods can be used to reduce the grounding resistance to the desired level:

• Install additional grounding rods and increase the distance between them.
• To set up a star, ring, or mesh type electrode arrangement,
• By penetrating to deeper levels, we can reach moist and conductive layers.
• Using soil conditioners such as bentonite,
• Increasing the surface area with a grounding strip.

Esco Elektrik's technical content regarding correct grounding methods and grounding types guides engineers and installers during the application phase.

Materials Used in Grounding

• Copper-clad steel grounding rods
• Galvanized strip and flat bar conductors
• Copper conductor and stranded wire
• Grounding busbars and connection clamps
• Thermoweld molds and welding powders
• Grounding boxes and connection points

The correct selection of these materials, proper installation techniques, and compliance with relevant standards form the basis of a long-lasting and safe grounding system.

Benefits of Grounding Systems

• It minimizes the risk of electric shock.
• It reduces the risk of fire caused by electrical faults.
• It extends the lifespan of electrical and electronic equipment.
• It supports production and business continuity.
• It ensures compliance with regulations and standards.

Frequently Asked Questions

What should the ideal grounding resistance be in ohms?

In residential and commercial buildings, the generally accepted target value is 5 Ω and below . In substations, sensitive electronic systems, and telecommunication facilities, this value can be further reduced (1–3 Ω range).

What happens if there is no grounding?

Without proper grounding, dangerous voltages can build up in equipment casings, leading to serious risks such as electric shock, equipment damage, and fire. Furthermore, lightning strikes and surges can cause significant damage to facilities and equipment.

What should a grounding cable be like?

The grounding conductor is usually selected from green-yellow colored copper conductors, and its cross-section must comply with the relevant standards and the short-circuit current it will carry. TS EN 60364-5-54 defines the minimum values for protective conductor cross-sections.

How often should grounding measurements be taken?

In industrial facilities and critical systems, it is recommended to measure grounding resistance at least once a year, and every six months for more sensitive applications. Regular periodic inspection and measurement are also mandatory in lightning protection systems.

What standards must be followed in grounding systems?

The main references for grounding applications in electrical installations in Turkey are TS EN 60364-5-54 , TS EN 50522 , TS EN 62305 , and the Electrical Internal Installations Regulation . Compliance with these standards is critically important both as a legal requirement and for operational safety.