What is Plate Earthing and why is it used?
Plate Earthing is a grounding method in which a metal plate made of copper or G.I. is buried deep in the earth. It provides a low-resistance path for fault current to flow safely into the ground, protecting electrical systems and people from electric shock or damage.
Thank you for reading this post, don't forget to subscribe!2. How is Plate Earthing constructed?
In plate earthing construction, a pit about 2.5 to 3 meters deep is dug. A copper or G.I. plate is placed vertically inside and surrounded by alternating layers of charcoal and salt. A watering pipe is installed to maintain moisture, and a G.I. or copper strip connects the plate to the electrical system.
3. What materials are used in Plate Earthing?
The main materials used in plate earthing include a copper or galvanized iron plate, charcoal powder, salt, Kalmi Sora, a PVC watering pipe, and a G.I. or copper strip. These materials help reduce earth resistance and ensure effective fault current dissipation.
4. How does Plate Earthing work?
During a fault, excess current flows through the earthing conductor into the buried plate. The plate then transfers this current into the earth through the surrounding salt and charcoal, which maintain soil conductivity. This process ensures safety and prevents electric shocks or equipment failure.
5. What are the advantages of Plate Earthing?
Plate earthing offers several advantages:
- Provides low earth resistance
- Ensures reliable performance under all soil conditions
- Suitable for heavy electrical loads
- Long-lasting and durable
- Easy to maintain using the watering pipe method
6. What are the applications of Plate Earthing?
Applications of plate earthing include:
- Transformer earthing
- Generator and motor installations
- Industrial and commercial buildings
- Electrical substations
- Domestic systems requiring high reliability
7. Why are charcoal and salt used in Plate Earthing?
Charcoal improves soil conductivity, while salt helps retain moisture around the plate. Together, they create a conductive layer around the electrode, ensuring fault current flows easily into the ground and minimizing earth resistance.
8. How much salt and charcoal are used in transformer Plate Earthing?
For transformer plate earthing, use around 50 kg of salt and 50 kg of charcoal to achieve low earth resistance. In domestic systems, 20 kg salt and 10 kg charcoal are sufficient. The exact amount depends on soil type and installation size.
9. How is moisture maintained in a Plate Earthing system?
A PVC or G.I. watering pipe with holes at the bottom is installed near the plate. Water is poured periodically into this pipe—called earthing charging—to maintain soil moisture and keep the system conductive and efficient.
10. What is the difference between Copper Plate and G.I. Plate Earthing?
A copper plate offers higher conductivity and durability, ideal for industrial use. A G.I. plate is more economical and suitable for residential systems. The choice depends on the load, soil type, and budget.
11. How is Plate Earthing maintained for long life?
Regularly pour water through the watering pipe, inspect joints for corrosion, and test earth resistance once a year. Replace salt and charcoal if needed. Proper maintenance ensures consistent conductivity and a long-lasting earthing system.
12. Why is Plate Earthing preferred for transformers and industries?
Transformers and industrial machines produce large fault currents. Plate earthing can handle these currents efficiently due to its low resistance and stable performance. It provides better protection for high-load equipment compared to pipe earthing.
Table of Contents
Introduction
In every electrical installation, earthing plays a vital role in ensuring safety and reliability. It protects people from electric shock and saves equipment from damage caused by fault currents.
Among various earthing systems, Plate Earthing is one of the most dependable and widely used methods, particularly in industrial and heavy-load installations.
In this system, a metal plate (made of either copper or galvanized iron) is buried deep into the ground to provide a low-resistance path for fault or leakage current to safely flow into the earth.
⚙️ What Is Plate Earthing?
Plate earthing is a traditional yet highly effective method of grounding electrical systems.
Here, a metallic plate acts as the main earthing electrode and is placed vertically inside the ground at a depth of about 3 meters (10 feet) or more — depending on the soil condition and electrical load.
A G.I. strip (Galvanized Iron) or copper strip connects this buried plate to the main electrical installation, providing a continuous and conductive path for any fault current to safely discharge into the earth.
Construction of Plate Earthing System
In the plate earthing system, several materials are carefully selected to ensure high conductivity, long life, and low resistance. Let’s understand each component in detail:
🪙 1. Earthing Plate
The main earthing electrode is a metal plate that can be made of either copper or galvanized iron (G.I.).
- Copper Plate: Usually 3.15 mm thick, having excellent conductivity and high durability.
- G.I. Plate: Commonly 6.3 mm thick and sized around 60 cm × 60 cm, which is easily available in the market.
- A copper plate (60×60×3.15 mm) or G.I. plate (60×60×6.3 mm) is placed vertically at the center of the pit.
For heavy-duty applications like transformers or large motors, the plate size may be increased up to 90 cm × 90 cm.
👉 As the plate size increases, the earth resistance decreases, but the installation cost also rises accordingly.
💧 2. Watering Pipe
A PVC or plastic pipe, about 2.5 to 3 meters long, is placed vertically inside the pit.
The pipe has 7–10 holes at its lower end to help water circulate easily around the plate.
This allows continuous moisture retention, which is essential for maintaining low earth resistance.
Through this pipe, water can be poured periodically to keep the surrounding soil cool and conductive.
⚡ 3. Earthing Strip
A G.I. or copper strip is tightly bolted to the plate and connects it to the main electrical system.
These strips are usually 10–12 mm wide, providing a reliable and strong conducting path for leakage or fault current to pass safely into the ground.
🌿 4. Charcoal and Salt Mixture
To improve conductivity, the earthing pit is filled with alternate layers of charcoal (carbon) and salt around the plate.
This combination helps retain moisture and ensures a low-resistance path for current flow.
💠 5. Kalmi Sora (Alum)
About 800 grams of Kalmi Sora (Alum) is often added during installation.
It helps maintain humidity and enhances the conductivity of the surrounding soil, especially in dry regions.
Layer Filling:
Around the plate, fill alternating layers of charcoal (carbon) and salt to maintain soil moisture and improve conductivity.
Each layer should be about 15 cm thick.
Important Notes
- Use 50 kg of salt and 50 kg of charcoal when earthing for transformers or heavy-load equipment.
- For domestic systems, 20 kg of salt and 10 kg of charcoal are sufficient.
- Maintain proper watering intervals to keep the system effective for years.
- Regular testing of earth resistance ensures safety and performance.
Materials Used in Plate Earthing
The efficiency of plate earthing largely depends on the quality and quantity of materials used. For general and transformer earthing, the following materials are typically required:
| Material | Quantity (General) | Quantity (Transformer) | Purpose |
|---|---|---|---|
| Salt | 20 kg | 50 kg | Maintains soil moisture and improves conductivity |
| Charcoal (Coal) | 10 kg | 50 kg | Reduces soil resistance and enhances conductivity |
| Kalmi Sora (Alum) | 800 g | 800 g | Helps retain humidity and improves soil conductivity |
| Copper or G.I. Plate | 60 cm × 60 cm (standard) | 90 cm × 90 cm (for heavy load) | Acts as the main earthing electrode |
| Copper or G.I. Strip | 10–12 mm | 10–12 mm | Connects the plate to the electrical system |
| PVC Watering Pipe | 2.5–3 m with drilled holes | 2.5–3 m with drilled holes | Used for maintaining moisture through water circulation |
Manufacturing (Installation) Method of Plate Earthing
Follow these step-by-step guidelines for proper plate earthing installation:
① Excavation
Dig a pit about 215 cm deep (approximately 2.1 meters) and around 100 cm × 100 cm (1 m × 1 m) wide.
The depth may vary depending on the soil type and moisture level.
This ensures the earthing plate remains below the permanent moisture level of the ground.
② Placing the Earthing Plate
Place the Copper or G.I. plate vertically at the center of the pit.
Ensure it is securely connected with a G.I. or copper strip that runs from the plate to the surface for connection with the main earthing point.
③ Filling the Pit
Fill the space around the plate with alternate layers of charcoal powder and salt.
Each layer should be approximately 15 cm thick.
This combination reduces earth resistance, keeps the soil moist, and improves conductivity.
④ Moisture Maintenance
Finally, pour Kalmi Sora (Alum) evenly over the top layer.
This helps retain soil humidity and prevents drying, especially during hot weather.
A watering pipe is installed to allow regular pouring of water, which maintains proper soil conductivity and low resistance over time.
⑤Earthing Strip Connection
For connecting the earthing plate to the electrical system:
- Use a copper strip if a copper plate is installed, or a G.I. strip if a G.I. plate is used.
- The strip is securely connected to the plate using nut and bolt arrangements.
- For long-lasting performance and better conductivity, the joints can also be brazed instead of using ordinary nuts and bolts.
This ensures a strong, corrosion-free, and low-resistance path for fault current to flow safely into the ground.
⑥ Water Pipe Installation (Earthing Charging System)
A PVC or G.I. water pipe is installed vertically near the plate, and it is tightened to the plate with a nut.
This pipe serves an essential purpose — maintaining humidity and soil moisture around the earthing plate.
- The pipe should extend slightly above ground level and remain in an upright position.
- Water can be poured into this pipe periodically to keep the surrounding soil moist and conductive.
- This regular watering process is known as “Earthing Charging.”
7. Filling and Surface Covering
After all the connections and fittings are done, the pit is filled with original soil.
The top surface is then covered with a cement box of size 60 cm × 60 cm for protection.
A G.I. lid is placed over the box to keep it closed and safe from dust, debris, and rainwater.
This protective box makes future maintenance easier — you can open the G.I. lid from time to time and pour water through the pipe to recharge the earthing system and maintain its effectiveness.
Tip: If you are using brazed copper or silver connections, then avoid using nuts and bolts to prevent corrosion and ensure long-term stability.
All the materials mentioned above are easily available in ready-made packets in the market.
Working Principle of Plate Earthing
When a fault occurs in an electrical system and a current leakage takes place, this current flows through the earthing strip to the metal plate buried in the ground.
From the plate, the current travels directly into the earth through a low-resistance path, preventing electrical shock and protecting both people and equipment.
The charcoal, salt, and alum surrounding the plate maintain soil conductivity and moisture, ensuring smooth current flow and minimal resistance.
Advantages of Plate Earthing
- ✅ Low Earth Resistance: Offers a safe, low-resistance path to discharge fault current.
- ✅ Long Life: Copper or G.I. plate provides durable performance when installed properly.
- ✅ Ideal for Heavy Loads: Suitable for transformers, generators, and industrial setups.
- ✅ Consistent Operation: Works effectively under varying soil and weather conditions.
- ✅ Easy Maintenance: Moisture can be maintained easily using the watering pipe.
Applications of Plate Earthing
- Industrial and commercial buildings
- Transformer substations
- High-voltage and heavy-load equipment
- Large motors and generator installations
- Domestic systems requiring high reliability
Copper Plate vs G.I. Plate – Comparison
| Type | Conductivity | Cost | Durability | Common Use |
|---|---|---|---|---|
| Copper Plate | Excellent | Expensive | Long-lasting | Heavy industries and substations |
| G.I. Plate | Moderate | Affordable | Good | Homes and small industries |
🧠 Conclusion
Plate earthing is one of the most dependable and long-lasting grounding methods used worldwide.
It ensures that any leakage or fault current flows safely into the earth, preventing electric shocks and protecting valuable equipment.
By using quality materials like copper or G.I. plates, maintaining proper charcoal-salt layers, and ensuring regular earthing charging, you can achieve low resistance, high reliability, and maximum electrical safety.