IEC 60364-5-51:2005

Overview

IEC 60364-5-51:2005 - "Electrical installations of buildings - Part 5-51: Selection and erection of electrical equipment – Common rules" specifies common rules for selecting and erecting electrical equipment in buildings. The standard ensures compliance with protection measures for safety, correct functioning for intended use, and provisions appropriate to foreseeable external influences. This edition introduced Clause 516 on mitigation of protective conductor currents and an informative Annex B (extracted from IEC 61140) on protective conductor currents, plus corrections to Table 51.

Key topics and requirements

• Scope and general rules (Clause 510): equipment selection and erection to meet safety and functional requirements.
• Compliance with standards (Clause 511): equipment shall comply with appropriate IEC/ISO standards or be agreed by specification/installer where none exist.
• Operational conditions (Clause 512): equipment must be suitable for the nominal voltage, current, frequency and power conditions of the installation and capable of withstanding abnormal currents and switching stresses.
• External influences (Clause 512.2): selection by degree of protection or conformity to tests (see Table 51A). Where equipment lacks required characteristics, additional protective measures may be provided without impairing operation.
• Accessibility, identification and interference prevention (Clauses 513–515): requirements for access, marking/identification and prevention of mutual detrimental influence between devices.
• Mitigation of protective conductor currents (Clause 516): new measures to manage currents in protective conductors to maintain safety and compatibility.
• Annexes: informative and normative annexes cover external influence lists, environmental parameter interdependence, mechanical classifications, macro-environment classification, permissible protective conductor currents and restructuring guidance for IEC 60364 parts.

Practical applications and users

Who uses IEC 60364-5-51:

• Electrical designers and consulting engineers specifying equipment for building installations
• Electrical contractors and installers implementing wiring, enclosures and protective measures
• Safety officers and inspection authorities verifying compliance with installation rules
• Manufacturers referencing required construction or degree-of-protection attributes for intended environments

How it is used:

• Select equipment rated for site voltage, current, frequency and environmental class (temperature, humidity, mechanical and electromagnetic influences)
• Choose appropriate IP/enclosure ratings or additional protective measures for outdoor, damp or corrosive locations
• Implement earthing, protective conductor planning and mitigations for protective conductor currents to preserve safety and EMC

Related standards

Key cross-references include:

• IEC 60364‑4‑41 (protection against electric shock)
• IEC 60364‑5‑52 (wiring systems) and IEC 60364‑5‑54 (earthing/protective conductors)
• IEC 61140 (protective conductor currents / protection against electric shock)
• IEC 60529 (IP Code, degrees of protection) and IEC 61000 series (EMC)

IEC 60364-5-51 is essential for ensuring that building electrical installations are specified and installed to meet both safety and functional expectations under real operational and environmental conditions.