How to Read and Understand IEC Standards: A Practical Guide for Engineers

by Ohm Engineering Works | Apr 22, 2025 | Electric Company

In the world of electrical engineering, compliance with international standards is non-negotiable. One such vital standard is IEC 61439, which governs low-voltage switchgear and controlgear assemblies. However, reading an IEC standard for the first time can feel overwhelming due to its formal structure and technical depth.

This article provides a clear, professional approach to understanding IEC standards—specifically IEC 61439—so you can confidently interpret, apply, and respond to them in real-world projects.

1. Understand the Structure of IEC Standards

Most IEC standards follow a consistent layout. Familiarizing yourself with this structure is the first step:

• Scope – Defines what the standard covers and what it excludes.

• Normative References – Lists other IEC standards that must be referred to.

• Terms and Definitions – Clarifies key terminology used throughout the document.

• Requirements – Details specific technical and constructional requirements.

• Verification (Testing) – Explains how compliance must be validated.

• Annexes – Provide additional tables, explanations, or informative guidance.

Tip: Start by reading the Scope, Terms and Definitions, and Verification sections before diving into the technical clauses. This builds context for what's expected.

2. Deep Dive into IEC 61439: Key Sections You Must Know

IEC 61439 is a multi-part standard, but Part 1: General Rules forms the foundation. Here's how to read it effectively:

Clause 1 – Scope

This section outlines the types of assemblies covered—typically low-voltage assemblies up to 1000 V AC or 1500 V DC.

Clause 3 – Terms and Definitions

Do not skip this. It defines terms like:

• Functional unit

• PEN conductor

• Main circuit

• Forms of internal separation (Form 1 to Form 4)

Understanding these terms ensures clarity when interpreting technical requirements later.

Clause 6 – Constructional Requirements

This clause outlines:

• Mechanical strength

• Degree of protection (IP ratings)

• Clearances and creepage distances

• Protection against electric shock

Clause 10 – Design Verification

This is one of the most critical sections. It explains how manufacturers or designers must prove compliance—via:

• Type testing

• Design rules

• Reference to previously verified designs

3. Interpreting the Requirements: A Step-by-Step Method

As you read each clause, ask yourself:

• What is the standard requiring?

• Is the clause mandatory or conditional?

• Does it apply to your type of assembly?

• What are the performance limits or test parameters?

Example Interpretation:

Clause 10.10.2 – Verification of Temperature Rise

Requires proof that under rated load conditions, the temperature rise of components remains within safe limits. This can be validated through testing or simulation.

4. Leverage Tables, Figures, and Annexes

Many technical constraints—like test values, limits, and verification criteria—are found in tables and annexes. Examples include:

• Table 6 – Degree of protection

• Annex D – Guidance on forms of separation

• Table 13 – Design verification options

Spend time understanding these, as they form the basis for compliance.

5. Cross-Referencing Other Standards

IEC 61439 often refers to other IEC standards, such as:

• IEC 60947 – For switchgear components

• IEC 60529 – For IP ratings

While you don't need full versions of all related standards, a summary or overview can help you understand interdependencies.

6. How to Apply or Respond Professionally to IEC Clauses

When responding in a compliance document, tender, or client report, always:

• Reference clause numbers

• Use precise terminology

• Support with design evidence, calculations, or test reports

Example Compliance Statement:

“As per IEC 61439-1 Clause 10.9, the assembly has been verified for dielectric properties using type-tested insulation materials and spacing clearances exceeding the required limits.”

This kind of language demonstrates both understanding and professionalism.

7. Tips for Mastering IEC Standards

• Use a highlighter or digital annotation tool to mark important clauses.

• Create a glossary of frequently used definitions from Clause 3.

• Develop a clause summary sheet for quick reference.

• Attend training sessions or webinars offered by major manufacturers (e.g., Schneider, ABB, Siemens).

• Practice with real-life cases – apply the standard to your own panel designs or product evaluations.

Final Thoughts

Reading and applying IEC standards may seem complex at first, but with a systematic approach, even the most technical documents become manageable. IEC 61439, in particular, is essential for ensuring the safety, reliability, and standardization of low-voltage assemblies.

By following these steps and maintaining a methodical approach, you not only ensure compliance but also position yourself as a knowledgeable and responsible electrical professional.