IEC Quick Reference
Key IEC and IEEE standards for electrical system design and installation.
IEC 60364 — Low-Voltage Electrical Installations
The foundational IEC standard for the design, erection, and verification of low-voltage electrical installations. Adopted internationally (as national variants like BS 7671, AS/NZS 3000).
Fundamental principles — protection for safety, design, verification.
Protection against electric shock — automatic disconnection of supply (ADS).
Protection against overcurrent — overload and short-circuit protection coordination.
Selection and erection of wiring systems — current-carrying capacity, cable installation methods, derating factors.
Earthing arrangements and protective conductors — TN, TT, IT systems.
Verification — initial and periodic inspection and testing procedures.
IEC 60909 — Short-Circuit Currents in Three-Phase AC Systems
Calculation of short-circuit currents using the equivalent voltage source method. Used worldwide for equipment rating, protection coordination, and system design.
Calculation of currents — uses voltage factor c and impedance methods for Ik″, Ip, Ib, Ith.
Voltage factor c: cmax = 1.1 for max SC current, cmin = 0.95 for min SC current.
Network feeding point impedance calculation from upstream transformer data.
Symmetrical components method — positive, negative, and zero sequence impedances.
Balanced and unbalanced short-circuit types: 3-phase, 2-phase, 1-phase-to-earth.
IEC 61642 — Industrial AC Networks Affected by Harmonics — Power Factor Correction
Guidelines for application of capacitor banks in networks with harmonic distortion. Addresses detuned reactors, THD limits, and capacitor protection.
Effect of harmonics on capacitors — resonance risk at harmonic orders matching system natural frequency.
Detuned reactor design — 7% or 14% detuning to avoid parallel resonance with 5th/7th harmonics.
Capacitor bank switching strategies — fixed, automatic, thyristor-switched.
Protection requirements — overcurrent, overvoltage, and unbalance protection for capacitor banks.
IEC 60076 — Power Transformers
Complete standard for power transformers covering ratings, impedance, temperature rise, and testing.
General — rated power, rated voltage, rated frequency, cooling classification (ONAN, ONAF, etc.).
Temperature rise — limits for winding and oil temperatures at rated load.
Ability to withstand short circuit — mechanical and thermal withstand requirements.
Loading guide — permitted overloading based on ambient temperature and prior loading.
IEC 60038 — Standard Voltages
Defines the standard voltage levels for AC and DC systems worldwide.
LV: 230/400V (50Hz), 120/240V (60Hz) — single and three-phase.
MV: 1 kV to 35 kV nominal voltage series.
HV: 66 kV, 110 kV, 132 kV, 220 kV, 330 kV, 500 kV.
IEEE 1584 — Arc-Flash Hazard Calculations
Standard for performing arc-flash hazard calculations to determine incident energy and arc-flash boundaries. Used globally alongside IEC standards.
Model applicability — valid for 208V to 15kV, 700A to 106kA bolted fault current.
Incident energy calculation method — uses arcing current, working distance, electrode configuration.
Arc-flash boundary determination — distance at which incident energy = 1.2 cal/cm².
Electrode configurations: VCB, VCBB, HCB, VOA, HOA — each has different arc energy characteristics.
NEC vs IEC — Key Differences
| Aspect | NEC (NFPA 70) | IEC 60364 |
|---|---|---|
| Scope | USA and adopted territories | International (170+ countries) |
| Voltage Standard | 120/240V, 480V (60Hz) | 230/400V (50Hz) |
| Wire Sizing | AWG / kcmil | mm² cross-section |
| Earthing Systems | Grounded / Ungrounded | TN-S, TN-C-S, TT, IT |
| Conduit Fill | Chapter 9 tables | Installation methods + derating |
| Motor Circuits | Article 430 (FLC tables) | IEC 60034 (nameplate) |
| Short Circuit | IEEE methods | IEC 60909 (cmax/cmin) |
| Update Cycle | 3-year (2023, 2026...) | Varies by standard |
Disclaimer: This quick reference is for informational purposes only. IEC standards are copyrighted by the International Electrotechnical Commission. Always consult the full standard documents, available from webstore.iec.ch, for design and compliance decisions.