Earthing Strip Size Calculator

To calculate the earthing strip size, use the IEC formula S = (I × √t) / K. First, convert your Fault Current (I) to Amps. Multiply it by the square root of the Fault Duration (t) in seconds. Finally, divide the result by the Material Constant (K) (e.g., 226 for Copper). The result is the minimum required cross-sectional area in mm².

Earth rod sizing depends on the soil resistivity and the required fault current dissipation. Typically, the diameter (e.g., 14mm, 17mm) is selected based on mechanical strength to penetrate the ground, while the length (e.g., 2m, 3m) determines the contact area with the soil to lower resistance. You can use our Earthing Rod Size Calculator for precise results.

A 2.5 mm² copper cable can typically carry between 18 Amps to 24 Amps depending on the installation method (e.g., enclosed in conduit vs. clipped direct) and ambient temperature. It is commonly used for standard power circuits in residential wiring.

The earthing busbar should handle the maximum fault current of the system. A common rule of thumb is to size the main earthing busbar to be at least equal to or larger than the main protective earthing conductor. It is often calculated using the same thermal withstand formula (S = I√t / K) with a safety factor applied (usually 1.2 to 1.5 times the calculated area).

Deciding the strip size involves two main factors: Thermal Stability (calculated using the Fault Current and Duration) and Mechanical Strength. Even if the calculation allows for a very small strip, standards (like IEC 60364) dictate minimum physical dimensions (e.g., minimum thickness of 3mm for copper) to prevent mechanical damage and ensure longevity against corrosion.

A "size strip" or "earthing strip" refers to a flat rectangular conductor used for grounding. It is defined by its Width (W) and Thickness (T) (e.g., 25mm × 3mm). Flat strips are often preferred over round conductors for surface earthing because they offer a larger surface area for contact and are easier to mount on walls or structures.