LOW-VOLTAGE AC · THREE DISTINCT CHECKS

Earthing & Grounding Checks

Select one method. A PE thermal check, a TT protective-measure criterion and an analytical rod estimate answer different questions and must not be treated as one compliance result.

INPUTS

Select the calculation

Each method has its own reference and input set.

Method and reference

IEC 60364-5-54:2011+A1:2021, protective-conductor thermal withstand. k must come from the applicable material, insulation and temperature conditions. For t ≤ 5 s only; mechanical minimum, bonding, routing and disconnection remain separate checks.

Prospective earth-fault current through PE (kA)Protective-device clearing time (s, max 5)Verified adiabatic k factor (A√s/mm²)Measured installation RA including PE path (Ω)RCD rated residual current IΔn (mA)Selected touch-voltage limit (V)Soil resistivity (Ω·m)Embedded rod length (m)Rod diameter (mm)

Method boundaries and sources

The page separates three calculations because they have different inputs and evidence:

PE · IEC 60364-5-54: S = I√t/k. The next listed conductor size is only a catalogue aid; check mechanical minima and the complete protective-conductor design. Official standard IEC 60364-5-54.

TT · IEC 60364-4-41: RA,max = UL/IΔn, using measured installation RA. The result assesses this inequality only. Verify the selected UL under the applicable national and special-location rules. Official standard IEC 60364-4-41.

Rod estimate · R ≈ ρ/(2πL)[ln(4L/d) − 1]. This is an analytical approximation, not a normative pass/fail test. Confirm by field measurement under IEC 60364-6 with suitable equipment. Verification standard IEC 60364-6.

Standard and scope

Excluded from all three results: lightning protection, high-voltage earthing, soil stratification, multiple electrodes, RCD timing and selectivity, and complete automatic-disconnection verification.

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