Earthing Rod Size Calculator
Calculate optimal earthing rod dimensions for safe fault current dissipation
Earthing Rod Size Calculator
Based on Adiabatic Heating Principle
Results:
Required Cross-Sectional Area: 0.00 mm²
Minimum Rod Diameter: 0.00 mm
Recommended Rod Diameter: 0.00 mm
How to Use the Calculator
Step 1: Fault Current
- Determine maximum fault current
- Calculate from transformer capacity
- Consider system impedance
- Use worst-case scenario
- Enter value in Amperes
Step 2: Fault Duration
- Check protective device settings
- Consider circuit breaker trip time
- Include relay coordination time
- Use maximum clearing time
- Enter value in seconds
Step 3: Material Selection
- Choose appropriate rod material
- Consider corrosion resistance
- Check local standards
- Copper offers best conductivity
- GI is cost-effective option
Earthing Rod Fundamentals
Adiabatic Heating
During fault conditions, the earthing rod must:
- Safely conduct fault current to ground
- Withstand thermal stress without melting
- Maintain structural integrity
Material Properties
- Material constant (k) varies by conductor type
- Higher k values require smaller cross-sections
- Copper has highest thermal capacity
Key Considerations:
• Fault current magnitude and duration
• Material thermal properties
• Safety factors and standards compliance
Calculation Formulas
Cross-Sectional Area:
S = √(If² × t) / k
Rod Diameter:
d = √(4 × S / π)
Where:
If = Fault Current (A), t = Time (s), k = Material Constant
Example Calculation
Galvanized Iron Rod:
Fault Current: 30,000A
Fault Duration: 0.5s
Material: GI (k=80)
S = √(30,000² × 0.5) / 80 = 265.16 mm²
d = √(4 × 265.16 / π) = 18.4 mm
Recommended: 20 mm diameter rod
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