IEC electrical installation standards
The international standard IEC 60364 is the series of standards of the International Electrotechnical Commission for low-voltage electrical installations, with a structure of 8 parts and more than 20 specialized sections covering from fundamental principles to installations in swimming pools, electric vehicles, and photovoltaic systems.
Fundamental principles and scope
Section titled “Fundamental principles and scope”IEC 60364 establishes the requirements for the design, installation, and verification of electrical installations in buildings and other works, with the objective of ensuring the safety of persons, domestic animals, and property against dangers arising from the use of electricity. Part 1 defines the fundamental principles, assessment of general characteristics, and definitions applicable to the entire series. It applies to low-voltage installations up to 1000 V AC / 1500 V DC, covering from residential dwellings to medical locations, fairs, marinas, and transport vehicles.
The standard serves as a harmonizing reference for national wiring regulations, such as the UK BS 7671, which closely follows the section structure of IEC 60364 while incorporating additional provisions for local historical practices.
Protection against electric shock
Section titled “Protection against electric shock”Section 41 of IEC 60364 addresses protection against direct and indirect contacts. For protection against direct contact, insulation of live parts or installation of barriers with minimum protection degree IP2X or IPXXB for accessible top surfaces is required. Protection against indirect contact is achieved by automatic disconnection of supply, using residual current protective devices and coordination with the standardized earthing arrangements in Section 54.
| Earthing arrangement | Technical description |
|---|---|
| TN-S | Neutral and protective conductor separated throughout the installation |
| TN-C-S | Neutral and protection combined in part of the installation |
| TT | Neutral earthed at supply, exposed conductive parts earthed independently |
| IT | Supply isolated from earth or connected to earth via impedance |
Protection against overcurrents and thermal effects
Section titled “Protection against overcurrents and thermal effects”Section 43 defines protection against overloads and short-circuits. Every circuit must have overcurrent protective devices that interrupt currents exceeding the continuous current-carrying capacity of the conductors. Protection against thermal effects in Section 42 requires that electrical equipment does not generate surface temperatures capable of causing ignition in adjacent materials; for example, in atmospheres with dust or flammable fibers, the surface temperature is limited to a maximum of 200 °C / 392 °F under normal conditions.
Selection and installation of equipment
Section titled “Selection and installation of equipment”Part 5 of IEC 60364 is composed of seven sections governing the selection and installation of all electrical system components:
| Section | Main content |
|---|---|
| 51 | Common rules for equipment selection according to external influences |
| 52 | Wiring systems, installation methods and current capacities |
| 53 | Protection, isolation, switching and control devices |
| 54 | Earthing arrangements and protective conductors |
| 55 | Miscellaneous equipment: generator sets, auxiliary circuits, lighting |
| 56 | Safety services such as emergency lighting and fire pumps |
| 57 | Stationary secondary batteries |
Section 52 contains the criteria for cable sizing according to current-carrying capacity, with capacity tables considering installation methods such as embedded conduits (method B1) or perforated trays (method F). For a 2.5 mm² / 14 AWG copper cable with PVC insulation in embedded installation, the typical capacity is 18.5 A.
Verification of installations
Section titled “Verification of installations”Part 6 establishes the verification procedures that every new or modified installation must pass before commissioning. It includes visual inspection to check that equipment complies with safety standards, is correctly selected, and shows no visible damage. Mandatory tests include continuity of protective conductors, insulation resistance (minimum 0.5 MΩ for test voltages of 500 V DC in circuits up to 500 V), polarity test, measurement of fault loop impedance, and tripping of residual current devices.
R_{insulation} > 0.5 MΩ for nominal circuit voltages ≤ 500 V
Installations in special locations
Section titled “Installations in special locations”Part 7 covers more than 20 locations with specific risks, defining additional protection measures:
| Section | Special location |
|---|---|
| 701 | Bathrooms and showers: volumes 0, 1 and 2 with different IP protection degrees |
| 702 | Swimming pools and other pools: safety distance requirements |
| 708 | Caravan parks and campsites |
| 709 | Marinas and pleasure craft |
| 710 | Medical locations |
| 712 | Solar photovoltaic power supply systems |
| 722 | Supply for electric vehicles |
| 740 | Temporary installations at fairs, amusement parks and circuses |
Energy efficiency and functionalities
Section titled “Energy efficiency and functionalities”Part 8 introduces modern functional aspects such as energy efficiency in electrical installations (Section 8-1) and prosumer installations (Sections 8-82 and 8-3). Section 8-1 specifies methodologies for evaluating the energy performance of the complete electrical system, including optimal transformer location, reactive energy compensation, and load management. The prosumer sections address the integration of distributed generation and storage, allowing bidirectional operation of low-voltage installations.
Earthing and protective conductors
Section titled “Earthing and protective conductors”Section 54 defines earthing systems and protective conductors, establishing that every installation must have an earthing electrode connected to the main earthing terminal. The standard recognizes optional auxiliary electrodes, such as additional rods connected to equipment protective conductors, which need not comply with the 25 Ω resistance requirements typical of the NEC nor be sized according to the main earthing conductor. However, the physical earth must not be considered as an effective path for fault current, since the high contact resistance between electrode and soil prevents overcurrent devices from clearing the fault in safe times.
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What maximum voltage does IEC 60364 cover for low-voltage installations?
Section titled “What maximum voltage does IEC 60364 cover for low-voltage installations?”IEC 60364 applies to low-voltage electrical installations with nominal voltages up to 1000 V AC and 1500 V DC, covering all common distribution systems in residential, commercial, and industrial buildings.
How many main parts does the IEC 60364 series have and how many specialized sections?
Section titled “How many main parts does the IEC 60364 series have and how many specialized sections?”The IEC 60364 series is composed of 8 main parts (Part 1 to Part 8) encompassing more than 20 sections dedicated to special locations such as bathrooms, swimming pools, medical locations, and photovoltaic systems.
What is the minimum insulation resistance required in the initial verification?
Section titled “What is the minimum insulation resistance required in the initial verification?”During initial verification of an installation according to Part 6, the insulation resistance must be greater than 0.5 MΩ when measured with a test voltage of 500 V DC in circuits up to 500 V nominal voltage.
How are earthing arrangements classified in IEC 60364?
Section titled “How are earthing arrangements classified in IEC 60364?”Section 54 classifies earthing arrangements into four main systems: TN-S with separate neutral and protection, TN-C-S with partial combination, TT with independent earthing of exposed conductive parts, and IT with isolated supply or supply connected to earth via impedance.
What IP protection requirements apply in bathroom volumes according to Section 701?
Section titled “What IP protection requirements apply in bathroom volumes according to Section 701?”Section 701 establishes three protection volumes: in volume 0 (inside the bathtub or shower) IPX7 is required, in volume 1 (up to 2.25 m / 7.38 ft above floor) IPX4, and in volume 2 (up to 0.6 m / 1.97 ft around volume 1) IPX4.
Which section regulates the installation of charging points for electric vehicles?
Section titled “Which section regulates the installation of charging points for electric vehicles?”Section 722 of Part 7 of IEC 60364 establishes the specific requirements for electric vehicle supply installations, including protection against shock, selectivity of protections, and conditions for connection to the network.
References
Section titled “References”- mikeholt.com: https://www.mikeholt.com/files/PDF/23_BG_250.54.pdf
- electrical4u.com: https://www.electrical4u.com/