Earth Cable Size Calculator
Accurate earth cable sizing for electrical earthing systems
Earth Cable Size Calculator
Compliant with IEC 60364 & IEEE 80 Standards
Results:
Minimum Cable Size: 0.00 mm²
Recommended Size: 0.00 mm²
How to Use the Calculator
Fault Current
- Enter maximum fault current in amperes
- This is typically the earth fault current
- Obtain from fault analysis studies
- Consider future system expansion
- Include safety margins
Fault Clearing Time
- Enter protection device clearing time
- Typical values: 0.1s to 3s
- Check relay/breaker settings
- Consider backup protection time
- Use maximum expected time
Material Selection
- Choose appropriate cable material
- Copper: Best conductivity (k=226)
- Aluminum: Cost effective (k=148)
- GI: Economical option (k=78)
- Consider corrosion resistance
Earth Cable Sizing Fundamentals
Thermal Considerations
Earth cable sizing must consider:
- Fault current magnitude and duration
- Cable material thermal properties
- Ambient and maximum temperatures
- Heat dissipation in soil
Safety Requirements
- Adequate current carrying capacity
- Mechanical strength for installation
- Corrosion resistance in soil
- Compliance with safety standards
Key Considerations:
Thermal capacity limits cable temperature rise
Soil conditions affect heat dissipation
Material properties determine sizing factors
Calculation Formulas
Earth Conductor Size:
PE(Sqmm) = √ (I(Fault-A)² × t(s)) / k
Where:
I(Fault-A) = Fault Current in Amps
t(s) = Time in Seconds
k = Material Constant
Material Constants:
Copper: k = 226, Aluminum: k = 148, GI: k = 78
Example Calculation
Earth Cable Sizing:
Fault Current: 5000A
Fault Time: 1s
Material: Copper (k=226)
PE = √ (5000² × 1) / 226 = √ (25,000,000) / 226 = 5000 / 226 = 22.12 mm²
Minimum Size = 22.12 mm²
Recommended = 25 mm² (next standard size)
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