Electrical Earthing: A Comprehensive Guide to Grounding

Electrical earthing, also known as grounding, is a crucial safety measure designed to channel electrical energy directly to the earth in the event of a short circuit or fault. This is achieved by connecting the neutral point of the power supply to the ground or by linking non-current-carrying parts of equipment to the earth.

Essentially, electrical earthing provides a low-resistance pathway for high-magnitude currents to safely discharge into the ground. It’s widely used across various sectors, including:

• Telecommunications
• Lightning arrestor systems
• Equipment body earthing
• Water treatment plants
• Residential buildings
• Banks and hospitals
• Heavy industries

There are generally two primary methods for earthing: conventional and maintenance-free earthing.

Conventional Earthing

This traditional method involves digging a sizable pit and positioning a Galvanized Iron (GI) pipe or copper plate at its center, surrounded by layers of charcoal and salt. However, conventional earthing requires periodic maintenance, including regular water pouring to maintain its effectiveness.

Maintenance-Free Earthing

A more modern and scientifically standardized approach.

Conventional earthing techniques can be further categorized into:

• Plate earthing
• Pipe earthing
• Rod earthing
• Strip earthing
• Earthing through water mains

Earth electrodes, made from materials like copper, cast iron, or galvanized iron, are essential components of earthing systems.

The primary benefits of earthing are:

• Protecting humans from electric shock
• Safeguarding expensive equipment and appliances from damage due to high currents during short circuits or faults.

The Role of Salt and Charcoal

In conventional earthing, layers of salt and charcoal are strategically used around the earthing electrode. These materials help maintain low resistance and consistent moisture levels, enhancing the earthing system’s performance.

Electrical Earthing Procedure: A Step-by-Step Guide

The following items are commonly used in electrical earthing procedures. The quantities may vary based on the power requirements and desired lifespan of the earthing system:

• Industrial salt (100 Kg)
• Charcoal (75 Kg)
• Copper plate (1 x 1 square feet)
• Copper wire (8mm diameter, 5 Kg)
• MS (Mild Steel) earthing pipe (6 feet length, circular shape) - 2 numbers (earthing electrodes)
• Underground power cable (35 mm diameter, length as per distance from pole to meter panel)

Here’s a step-by-step guide to rod-based electrical earthing:

• Step 1: Dig a pit near the electrical meter panel, approximately 6 feet deep and 2 x 2 feet wide.
• Step 2: Connect the copper plate to the end of the MS rod using copper bolts and wrap it securely with copper wire.
• Step 3: Insert the pipe vertically into the pit, ensuring the copper plate is at the bottom.
• Step 4: Fill the hollow part of the MS pipe and its surrounding area with salt.
• Step 5: Surround the MS pipe with charcoal.
• Step 6: Add a mixture of sand and concrete around the pipe.
• Step 7: Repeat steps 4 to 6 several times until the pit is filled to ground level.
• Step 8: Keep the copper wire accessible for connection to the appropriate point in the electrical meter panel.
• Step 9: Install one MS rod or pipe at the electrical pole and the other at the meter panel.

Qualities of Good Earthing

A well-designed and implemented earthing system should possess the following qualities:

• Low electrical resistance
• Good corrosion resistance
• Ability to repeatedly dissipate high fault currents

10 Advantages of Earthing

1. Provides an alternative path for fault current, protecting users from electrical hazards.
2. Saves lives by preventing electric shocks or fatalities through fuse activation.
3. Ensures that exposed conductive parts remain at safe potential levels.
4. Protects electrical equipment and appliances from damage caused by voltage surges, reducing repair or replacement costs.
5. Stabilizes voltage levels, ensuring equipment operates within specified ranges and preventing overvoltage.
6. Offers a safe pathway to dissipate lightning strikes and short-circuit currents.
7. Essential for dissipating static charges that can accumulate and pose hazards.
8. Minimizes electromagnetic interference, improving the performance of sensitive electronic devices and communication systems.
9. Enables the detection of ground faults, triggering protective devices like GFCIs to disconnect power and enhance safety.
10. Proper grounding is often legally mandated and ensures compliance with electrical safety codes, mitigating legal liabilities.

5 Disadvantages of Earthing

1. Grounding electrodes and conductors can corrode over time, increasing resistance and reducing effectiveness.
2. Requires regular maintenance to ensure continued effectiveness; corroded or damaged components must be repaired or replaced.
3. Designing and implementing proper grounding systems can be complex and costly, especially in large or specialized facilities.
4. Some grounding materials, like copper, raise environmental concerns related to mining, processing, and disposal.
5. Improper grounding can be more dangerous than no grounding, providing a false sense of security without adequate protection.

Conclusion

Electrical earthing offers significant advantages, including enhanced safety through the prevention of electric shocks and protection from lightning and voltage surges. It contributes to stable voltage levels, reduces electromagnetic interference, and dissipates static electricity. While it requires maintenance and may face challenges like corrosion and complex implementation, proper grounding is fundamental for electrical safety and system reliability.