IEC 60364-7-704:2017

Overview

IEC 60364-7-704:2017 is part of the IEC 60364 series on low-voltage electrical installations and sets out particular requirements for construction and demolition site installations. It applies to temporary fixed or moveable electrical installations used during construction, repair, alteration, extension or demolition work and intended to be taken out of service on completion. Administrative areas of sites (offices, canteens, dormitories, toilets) are excluded. This third edition clarifies the scope, compliance with standards and requirements for isolation devices.

Key topics and technical requirements

• Scope and structure: Supplements and modifies the general IEC 60364 Parts 1–6 requirements where applicable; particular clauses appear as 704.xxx and work together with general parts.
• Protection for safety: Specifies which protective measures are not acceptable on sites (for example, the measures “obstacles” and “placing out of reach”, and certain measures from Annex C of IEC 60364‑4‑41).
• Electric shock protection:
  • Circuits supplying socket-outlets and hand‑held equipment (rated ≤ 32 A) must be protected by:
    • automatic disconnection of supply plus additional protection by residual current devices (RCDs) with rated residual operating current ≤ 30 mA, or
    • supply by SELV or PELV, or
    • electrical separation (individual isolating transformers or separate windings).
  • For socket-outlet circuits with rated current > 32 A, residual current devices are required as disconnection devices.
• Selection and erection: Addresses compliance with relevant standards, operational conditions and external influences for wiring systems, isolation, switching and control.
• Site-specific considerations: Clearance coordination for overhead lines must be agreed with the line owner, considering cranes, scaffolding and other site equipment.
• Verification and safety services: Includes requirements for verification of installations and application of appropriate safety services and switchgear.

Applications

IEC 60364-7-704:2017 is intended for:

• Temporary power distribution on construction and demolition sites
• Design and installation of distribution boards, site switchgear and portable socket‑outlet circuits
• Integration of generators and multiple supply sources on a single site
• Risk mitigation where heavy machinery (cranes, scaffolding) interacts with electrical infrastructure

Who uses this standard

• Electrical designers and consulting engineers for construction projects
• Site electricians and installation contractors
• Health & safety managers and site supervisors
• Test and inspection authorities and certification bodies
• Manufacturers of switchgear and assemblies for construction sites (ACS)

Related standards

• IEC 60364 (general parts 1–6)
• IEC 60309 series (industrial plugs and sockets)
• IEC 61439-4 (switchgear assemblies for construction sites)
• IEC 60245-4 (flexible cables and cords)

Keywords: IEC 60364-7-704:2017, construction site electrical installations, low-voltage, RCD, SELV, PELV, isolation, temporary power, construction and demolition site installations.