IEC 61643-21:2025 PDF

Low voltage surge protective devices - Part 21: Surge protective devices connected to telecommunications and signalling networks - Requirements and test methods

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Title (English):

IEC 61643-21:2025

Low voltage surge protective devices - Part 21: Surge protective devices connected to telecommunications and signalling networks - Requirements and test methods

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 85
Publication date:: October 20, 2025
Edition:: IEC IS 61643 edition 2 version 1
ICS:: 29.240.10

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Description (English):

IEC 61643-21:2025 is applicable to devices for surge protection against indirect and direct effects of lightning or other transient overvoltages. These devices are intended to be connected to telecommunications and signalling networks, and equipment rated up to 1 000 V RMS and 1 500 V DC. These telecommunications and signalling networks can also provide power on the same line, e.g. Power over Ethernet (PoE). Performance and safety requirements, tests and ratings are specified in this document. These devices contain at least one voltage-limiting component (clamping or switching) and are intended to limit surge voltages and divert surge currents. This second edition cancels and replaces the first edition published in 2000, Amendment1:2008 and Amendment 2:2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) New structure of IEC 61643-21 based on IEC 61643-01:2024; b) Several safety requirements based on IEC 61643-01:2024 have been added. This International Standard is to be used in conjunction with IEC 61643-01:2024.

Technical details

Technical committee: SC 37A - Low-voltage surge protective devices
SKU: IEC 61643-21:2025

Abstract

Overview

IEC 61643-21:2025 - "Low voltage surge protective devices - Part 21" specifies requirements and test methods for surge protective devices (SPDs) connected to telecommunications and signalling networks. It covers SPDs intended to protect equipment rated up to 1 000 V RMS and 1 500 V DC, including circuits that also carry power (e.g., Power over Ethernet / PoE). Devices covered contain at least one voltage‑limiting component (clamping or switching) and are designed to limit surge voltages and divert surge currents. This second edition is a technical revision aligned with IEC 61643-01:2024 and adds new structure and safety requirements.

Key topics and technical requirements

Scope & classification: Definitions, SPD types, mounting methods, end‑of‑life modes and configurations (single‑port, two‑port, multimode).
Electrical requirements: Protection against electric shock, continuous current handling, measured limiting voltage, operating duty, insulation resistance, dielectric withstand, behaviour under temporary overvoltages (TOV), impulse durability and reset behaviour.
Current‑limiting and safety: Tests and performance for current‑limiting SPDs, overstress/fault modes, short‑circuit protection for end‑of‑life.
Transmission & signal integrity: Requirements and test methods for insertion loss, return loss, near‑end crosstalk (NEXT), longitudinal balance and Bit Error Ratio (BER) for LAN/telecom links.
Mechanical, environmental & material tests: Mechanical strength, connections, creapage/clearance, heat resistance, tracking resistance, damp‑heat ageing.
Type testing & test procedures: Impulse tests (8/20 current, 1,2/50 voltage, combination wave), impulse durability, impulse reset, AC durability, total discharge current, and reduced test procedures. Annexes provide example test circuits, threat parameters and application guidance.
Marking & documentation: Manufacturer information requirements and data necessary for type testing and product labelling.

Practical applications

Protecting telecom and signalling equipment (switches, routers, PoE devices, signalling controllers) from indirect and direct lightning transients and other transient overvoltages.
Ensuring SPDs meet both safety and signal‑integrity requirements when installed in LANs, industrial control networks, railway signalling and telecom infrastructures.
Supporting product design, independent type testing, certification, procurement and compliance verification for low‑voltage telecom surge protection.

Who should use this standard

SPD manufacturers and designers (product development and compliance teams)
Test laboratories and certification bodies performing type testing
Network and telecom equipment manufacturers integrating surge protection
System integrators, installers and asset owners specifying surge protection for PoE, LAN and signalling systems
Procurement and regulatory compliance professionals

Related standards

IEC 61643-01:2024 (general requirements for low voltage SPDs) - IEC 61643-21:2025 is intended to be used in conjunction with IEC 61643-01:2024.

Keywords: IEC 61643-21, surge protective devices, telecommunications surge protection, PoE protection, low voltage SPD test methods, IEC surge protection standard.

Related standards

Mentioned in the description and other IEC standards

Abstract

Overview

Key topics and technical requirements

Scope & classification: Definitions, SPD types, mounting methods, end‑of‑life modes and configurations (single‑port, two‑port, multimode).
Electrical requirements: Protection against electric shock, continuous current handling, measured limiting voltage, operating duty, insulation resistance, dielectric withstand, behaviour under temporary overvoltages (TOV), impulse durability and reset behaviour.
Current‑limiting and safety: Tests and performance for current‑limiting SPDs, overstress/fault modes, short‑circuit protection for end‑of‑life.
Transmission & signal integrity: Requirements and test methods for insertion loss, return loss, near‑end crosstalk (NEXT), longitudinal balance and Bit Error Ratio (BER) for LAN/telecom links.
Mechanical, environmental & material tests: Mechanical strength, connections, creapage/clearance, heat resistance, tracking resistance, damp‑heat ageing.
Type testing & test procedures: Impulse tests (8/20 current, 1,2/50 voltage, combination wave), impulse durability, impulse reset, AC durability, total discharge current, and reduced test procedures. Annexes provide example test circuits, threat parameters and application guidance.
Marking & documentation: Manufacturer information requirements and data necessary for type testing and product labelling.

Practical applications

Protecting telecom and signalling equipment (switches, routers, PoE devices, signalling controllers) from indirect and direct lightning transients and other transient overvoltages.
Ensuring SPDs meet both safety and signal‑integrity requirements when installed in LANs, industrial control networks, railway signalling and telecom infrastructures.
Supporting product design, independent type testing, certification, procurement and compliance verification for low‑voltage telecom surge protection.

Who should use this standard

SPD manufacturers and designers (product development and compliance teams)
Test laboratories and certification bodies performing type testing
Network and telecom equipment manufacturers integrating surge protection
System integrators, installers and asset owners specifying surge protection for PoE, LAN and signalling systems
Procurement and regulatory compliance professionals

Related standards

IEC 61643-01:2024 (general requirements for low voltage SPDs) - IEC 61643-21:2025 is intended to be used in conjunction with IEC 61643-01:2024.

Keywords: IEC 61643-21, surge protective devices, telecommunications surge protection, PoE protection, low voltage SPD test methods, IEC surge protection standard.

IEC 61643-21:2025 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Practical applications

Who should use this standard

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Practical applications

Who should use this standard

Related standards

Related standards

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