CABLE DESIGN · IEC WORKFLOW

IEC Cable Sizing Calculator

Size a conductor against current-carrying capacity, installation method, derating, voltage drop and short-circuit thermal withstand in one traceable workflow.

IEC 60364-5-52IEC 60364-4-43Ib ≤ In ≤ IzΔU checkI²t / adiabaticCu / Al

Electrical load

Define the circuit operating point.

SystemVoltage VDesign current Ib AOne-way length mPower factorMax voltage drop %

Cable & installation

Reference current rating follows the selected IEC installation method.

ConductorInsulationLoaded conductorsData mode

Installation reference method

IEC 60364-5-52 reference method C.

Ambient air temperature °CBunched circuits / cablesAdditional derating factor

Automatic mode uses IEC 60364-5-52 Annex B reference current ratings. Air temperature correction uses Table B.52.14; buried methods D1/D2 use ground-temperature Table B.52.15.

Short-circuit thermal check

Select one calculation basis. Fields not used by the selected method are disabled.

Calculation basis

Prospective short-circuit current kA Clearing time s Total clearing let-through I²t A²s

I²t mode: the entered value must be the protective device's total-clearing let-through energy for the applicable prospective fault level. Breaking capacity (Icn/Icu/Ics) is not an I²t value.

k factor A√s/mm²Protective device In A

Ready to calculate.

RESULT

Selected conductor

READY

—mm²

Enter the design conditions and calculate.

Why this size?

Ampacity / protection minimum——

Voltage-drop minimum——

Short-circuit minimum——

Final size is the largest minimum required by the active criteria.

Ampacity——

Voltage drop——

Short-circuit——

Protection——

IEC reference method—

Base ampacity Iz,base—

Temperature factor Ca—

Grouping factor Cg—

Total factor—

Corrected ampacity Iz—

Short-circuit modelIsc × clearing time

Required S by short circuit—

Conductor resistance @ operating temp—

Estimated end voltage—

Before use: every active criterion must pass. For current-limiting protection, use verified total-clearing I²t from the protective-device manufacturer. Breaking capacity alone does not define conductor let-through energy.

Verification required: Results are calculation aids and are not guaranteed to be error-free or suitable for a specific project. Independently verify inputs, outputs, applicable standards, manufacturer data and project requirements before design release, procurement or installation.

Method

The ampacity engine uses the reference installation methods and current-carrying-capacity tables of IEC 60364-5-52:2009+A1:2024. Short-circuit thermal verification follows the adiabatic concept used in IEC 60364-4-43.

Ib ≤ In ≤ Iz | ΔU ≤ ΔUmax | I²t ≤ k²S²

Normative references: IEC 60364-5-52, Annex B · IEC 60364-4-43 · DIN VDE 0298-4 (VDE 0298-4):2023-06.

Prefer a guided verification?

Open the IEC Cable Design & Verification Workflow to work through one cable step by step from load and installation method to ampacity, protection, voltage drop, short-circuit thermal withstand and optional lifecycle economic screening. The workflow is currently PILOT.

Cable design guides and related calculators

Use the complete Cable Design cluster beside this calculator: cable sizing vs ampacity → IEC installation methods → temperature and grouping derating → three-phase voltage drop → short-circuit thermal withstand. For protection-side I²t context, see I²t let-through energy. For a North American project, use the separate NEC cable sizing calculator. To examine the upstream protection path, open the FaultChain short-circuit protection calculator.