Article 143 of the Korean Electrical Code (KEC) specifies the minimum cross-sectional area of protective earthing conductors (grounding wires) required to prevent electric shock in electrical installations. This calculator supports both calculation methods defined in KEC 143. Method A (proportional) instantly determines the minimum grounding conductor size based on the phase conductor cross-section. Method B (adiabatic equation) applies the formula S = โ(Iยฒรt)/k, using fault current (A), disconnection time (s), and a material-dependent k-factor for copper or aluminum conductors with PVC or XLPE insulation. Results are automatically rounded up to the nearest standard cable cross-section (SQ) available in the market, allowing immediate material procurement. This tool is designed for electrical engineers, electrician exam candidates, and on-site construction technicians.
Common Use Cases
๐๏ธ
New Building Electrical Design
Apply KEC 143 Method A across all circuits in a distribution panel to determine grounding wire sizes in bulk during the design phase.
๐ญ
Industrial Fault Current Calculation
Enter transformer secondary short-circuit current, breaker trip time, and cable material to precisely calculate grounding conductor size using Method B.
๐
Electrician Exam Preparation
Verify KEC 143 grounding calculations (Method A and B) with real input values to practice the formula types that appear on the exam.
๐
On-Site Construction & Inspection
Quickly verify the adequacy of grounding conductor sizes on-site and recalculate immediately when design changes occur to ensure code compliance.
How to Use
1
Select Calculation Method
Choose Method A (proportional) from the top tab if you only know the phase conductor size, or Method B (adiabatic) if you have fault current and disconnection time data.
2
Enter Input Values
For Method A, enter the phase conductor cross-section in mmยฒ. For Method B, enter fault current (A, RMS), disconnection time (seconds), and select the cable material combination (Cu/PVC, Cu/XLPE, Al/PVC, or Al/XLPE).
3
Review Results
The theoretical minimum size and the recommended standard SQ size (rounded up to the nearest commercially available cable) are displayed. The recommended size is the most economical minimum that satisfies KEC 143.
4
Apply to Design
Incorporate the recommended SQ into your electrical drawings or material orders. Always verify the final specification with the supervising electrical engineer and local authority.