The actual load-carrying capacity of a cable Iz = Iz₀ × k_temperature × k_grouping It is found by: the base value (Iz₀) in the catalog is corrected according to the ambient temperature and the number of circuits laid together. The design current (Ib) should not exceed this corrected value.

Iz = Iz₀ × k_temperature × k_grouping · Ib ≤ Iz
Example calculation: Catalog Iz₀ = 76 A, ambient 40 °C (k=0.87), 3 circuits together (k=0.70) → corrected Iz = 76 × 0.87 × 0.70 ≈ 46 A; suitable if design current is 40 A.

Cable Load & Correction Factor (Ampacity)

Adjust your cable's catalog current carrying capacity according to ambient temperature and grouping; check if it meets the design current.

Corrected capacity trace
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Correction factor
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Notes: Iz = Iz₀ × k_temperature × k_grouping (IEC/HD 60364-5-52). Catalog value Iz₀ from the cable manufacturer's table / relevant standard Correction factors are selected (depending on the laying method, number of conductors, and insulation). The correction factors are a reference for PVC 70°C; they are different for XLPE. The exact selection requires engineering verification.
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How is it calculated?

  1. Enter the design current (Ib) and catalog carrying capacity (Iz₀).
  2. Select the ambient temperature and the number of circuits to be laid together.
  3. Press Calculate; the corrected capacity and eligibility will be displayed.

Frequently Asked Questions

What factors affect cable load-carrying capacity?
The cross-section varies depending on the conductive material, insulation (PVC/XLPE), installation method, ambient temperature, and the number of circuits laid together.
Where can I find the basic bearing capacity (Iz₀)?
The cable specifications are obtained from the cable manufacturer's catalog or from IEC/HD 60364-5-52 tables, according to the laying method.
Why are corrective factors applied?
High ambient temperature and the proximity of cables make heat dissipation difficult; therefore, capacity is reduced (derating).

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This tool and its content are for general informational purposes only; they do not constitute a binding inspection/declaration of conformity. Definitive results will be determined through on-site inspection in accordance with relevant legislation and standards. Get a quote →