IEC 60947-7-1:2025

Overview

IEC 60947-7-1:2025 is the latest international standard governing low-voltage switchgear and controlgear ancillary equipment, specifically focusing on terminal blocks for copper conductors. Published by the International Electrotechnical Commission (IEC), this fourth edition updates and replaces the 2009 version, introducing significant technical revisions to better address modern industrial requirements.

The standard applies primarily to terminal blocks with screw-type or screw-less-type clamping units, intended for industrial environments or similar applications. These terminal blocks are designed to connect round copper conductors with cross-sections ranging from 0.05 mm²/30 AWG up to 300 mm²/600 kcmil, suitable for circuits with rated voltages of up to 1,000 V AC (up to 1,000 Hz) or 1,500 V DC. IEC 60947-7-1 also specifies standardized testing methods for verifying mechanical, electrical, and thermal performance under defined conditions.

Key Topics

• Scope and Application: Terminal blocks for copper conductors used in industrial controlgear with rated voltages not exceeding 1,000 V AC or 1,500 V DC.
• Terminal Block Types: Includes test disconnect terminal blocks covered in Annex D, with both screw-type and screw-less-type clamping units.
• Conductor Cross-section Range: Covers a broad range from very small (0.05 mm²/30 AWG) to large sizes up to 300 mm²/600 kcmil.
• Technical Revisions in 2025 Edition:
  • Extension for smaller conductor cross-sections.
  • Introduction of Contact Pressure via Insulation (CoPI) test.
  • Inclusion of informative annexes such as Annex E for larger cross-sections and Annex A for main terminal block characteristics.
  • Reorganization of tables and annexes for clarity and usability.
  • Implementation of AWG conductor size equivalences with examples.
• Performance Specifications:
  • Voltage ratings and short-time withstand currents.
  • Clearances and creepage distances to ensure electrical safety.
  • Temperature rise limitations to prevent overheating.
  • Dielectric properties, voltage drop, and electromagnetic compatibility (EMC).
• Testing Requirements:
  • Verification of mechanical strength and clamping integrity.
  • Electrical tests including dielectric strength, voltage drop, and short-time withstand current.
  • Thermal and EMC tests for durability and compliance.
  • Specific ageing tests for screwless terminal blocks.

Applications

IEC 60947-7-1:2025 terminal blocks are integral components in:

• Industrial Control Panels: Providing reliable and safe electrical connections in motor controllers, machine automation, and process control.
• Power Distribution Systems: Serving as connectors in low-voltage switchgear assemblies.
• Building Automation: Ensuring secure wiring in HVAC systems, lighting control, and security installations.
• Renewable Energy Systems: Enabling durable connections for solar inverters and energy management systems.
• Transportation and Railways: Used in controlgear for low-voltage signaling and power distribution.

The standardization of electrical, mechanical, and safety requirements enhances the reliability and interoperability of terminal blocks across various industrial and commercial applications, reducing risks such as electrical failure, fire hazards, and maintenance challenges.

Related Standards

For comprehensive safety and performance, IEC 60947-7-1 should be used in conjunction with related standards including:

• IEC 60947 Series: The overarching standard series for low-voltage switchgear and controlgear.
• IEC 60947-1: General rules applicable to all low-voltage switchgear and controlgear products.
• IEC 60999-1: Connecting devices for low-voltage circuits and their corresponding safety requirements.
• IEC 60204-1: Safety of machinery - electrical equipment of machines, applicable for integrating terminal blocks in machinery.
• IEC 61800-5-1: Adjustable speed electrical power drive systems - safety requirements.
• National and regional wiring regulations: Compliance with local electrical codes and installation practices.

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