What is Earthing How Earthing Works
1. What is Earthing (Grounding)?
Earthing is the process of connecting the non-current-carrying metal parts of electrical equipment to the earth so that:
Fault current goes safely into the ground
Electric shock is preventedEquipment is protected from damage
Fire risk is reduced
👉 In simple words:
Electricity chooses the earth instead of your body.
2. How Earthing Works (Working Principle)
During normal operation, current flows through live and neutral
If insulation fails, the metal body becomes liveEarthing provides a low-resistance path
Fault current flows to the ground
MCB / Fuse trips immediately
Person touching the body remains safe
Formula concept (for exams):
Low earth resistance ⇒ High fault current ⇒ Faster tripping
3. Main Parts of an Earthing System
Earth electrode (pipe / plate / rod)
Earthing conductor (copper or GI wire/strip)
Earthing clamp (shown in your image)
Earth pit (with charcoal & salt)
Earth inspection chamber
4. Types of Earthing (Very Important)
1. Pipe Earthing (Most common – BEST)
GI pipe driven into ground
Used in homes, buildings2. Plate Earthing
Copper or GI plate buried
Used in substations3. Rod Earthing
Copper/GI rod driven deep
Used where space is limited4. Strip/Wire Earthing
Used in industries & transmission lines👉 For houses: Pipe earthing is preferred.
5. Step-by-Step Procedure of Pipe Earthing
Step 1: Select Location
Moist soil area
Away from foundationNot waterlogged
Step 2: Digging the Pit
Size: 1 m × 1 m × 2.5–3 m deep
Deeper pit = better earthingStep 3: Install GI Pipe Electrode
GI pipe:
Length: 2.5 to 3 meters
Diameter: 38–50 mm
Place vertically in pit
Pipe should have holes for moisture contactStep 4: Fill with Charcoal & Salt
Layering method:
Charcoal (improves conductivity)
Salt (reduces resistance)Alternate layers around pipe
👉 This keeps soil moist & conductive
Step 5: Connect Earthing Wire
Use copper wire or GI strip
Connect wire to pipe using:
Copper clamp (left image)
GI clamp (right image)Tighten nuts firmly
Step 6: Watering Arrangement
Funnel or pipe provided
Regular watering maintains low resistanceStep 7: Inspection Chamber
Brick or PVC chamber on top
Cover with lidAllows testing & maintenance
Step 8: Connect to Main Earth Bus
Earthing wire goes to:
Main distribution board
Equipment bodyNeutral-earth link (as per design)
6. Why Charcoal and Salt Are Used?
| Material | Purpose |
|---|---|
| Charcoal | Absorbs moisture |
| Salt | Increases conductivity |
| Water | Keeps resistance low |
7. Standard Earthing Resistance Values
| Installation Type | Resistance |
|---|---|
| Residential house | ≤ 5 ohms |
| Commercial | ≤ 2 ohms |
| Substation | ≤ 1 ohm |
| Sensitive equipment | ≤ 0.5 ohm |
8. Materials Required (Complete List)
GI pipe (2.5–3 m)
Copper/GI earthing wireEarthing clamp
Charcoal (25–30 kg)
Salt (25–30 kg)
Water pipe/funnel
Bricks & cement
Inspection chamber cover
9. Cost of Earthing (India – Approx)
Normal House (Pipe Earthing)
| Item | Approx Cost (₹) |
|---|---|
| GI pipe | 600 – 1,200 |
| Copper/GI wire | 500 – 1,500 |
| Charcoal + Salt | 400 – 700 |
| Clamp & accessories | 200 – 400 |
| Labour | 1,000 – 2,000 |
👉 Total Cost: ₹3,000 – ₹6,000
Copper Plate Earthing (Costly)
| Total Cost | ₹10,000 – ₹18,000 |
10. Complete Mini Project Example (For Exams / Diploma / ITI)
Project Title:
Installation of Pipe Earthing System for Residential Building
Objective:
To provide safe grounding for electrical installation.
Method Used:
GI Pipe Earthing
Materials Used:
GI pipe, copper wire, salt, charcoal, clamp, inspection chamber
Procedure:
Pit dug → Pipe installed → Salt & charcoal filled → Wire connected → Watering done → Chamber fixed
Result:
Earth resistance achieved below 5 ohms, ensuring electrical safety.
11. Common Mistakes to Avoid
Loose clamp connection ❌
Dry soil without watering ❌Shallow pit ❌
Rusted wire ❌
Single earthing for heavy load ❌
Earthing is the process of connecting the exposed metal parts of electrical equipment to the general mass of earth to protect humans and equipment from electric shock