SGS : General Principles and Safeguards of IEC 62368-1

On December 20, 2020, EN 62368-1 and UL 62368-1 will become the mandatory safety standard for audio, visual, information and communication equipment for EU and US markets respectively.

EN 62368-1 or UL 62368-1 are based on IEC 62368-1(edition 2.0), which is the new standard to cover the products under IEC 60950-1 and IEC 60065. In comparison to these two standards, IEC 62368-1 has been totally rewritten and so its structure and logic are completely different.

IEC 62368-1 has three editions, 1.0, 2.0 and 3.0, and is built around three core principles:

• Principle 1: Product Safety Realization Steps
• Principle 2: Safeguards
• Principle 3: Energy Source Classification

In this article, we will introduce Principles 1 and 2 relating to editions 2.0 and 3.0.

Principle 1: Product Safety Realization Steps

Illustrated below, the concept behind this principle has been adopted from ISO/IEC Guide 51:2014.

Illustration 1 - Product Safety Realization Steps

The logic behind this principle is as follows:

• Step 1: try to use as low energy as possible to operate the product. If the energy used is low enough the product will inherently be safe to use and, usually, no safeguards will be required
• Step 2: if higher, hazardous energy levels are required, the product design must include sufficient safeguards to protect the user from the hazard(s)
• Step 3: if equipment safeguards conflict with the product's intended use, thereby making the safeguards impractical, instructional safeguards must be used
• Step 4: when the safeguards in Steps 2 and 3 prove to be insufficient or not applicable, additional safeguards beyond product design will be necessary

Understanding this principle will help manufacturers design safer and more compliant products, which apply the requirements of IEC 62368-1.

Principle 2: Safeguards

The structure laid out in Principle 1 leads to Principle 2 - the Safeguards - the concept of which is systematically introduced in IEC 62368-1.

Illustration 2 - IEC62368-1 Safeguards

At first glance, the safeguards detailed in IEC 62368-1, such as Supplementary, Instructional, Skill, etc., can seem complicated. In fact, as the illustration above shows, the concept behind these safeguards of these can be easily understood.

Under IEC 62368-1, Safeguards are divided by two methods - Approaches or Levels. These refer to:

1. Approaches - methods by which the safeguard functions
2. Levels - the strength of the safeguard

In the above graphic, it should be noted the safeguards in grey - Installation, Personal, Precautionary, Skill - are not specified in IEC 62368-1 but are assumed effective when the term is used.

Application of Safeguards

By comprehending Principles 1 and 2, manufacturers can begin to understand how the safeguard requirements for IEC 62368-1 should be applied. This can be seen from two different perspectives - safeguards by different approaches or safeguards by different levels.

To look at the application of safeguards via the different approaches method, the different safeguards defined in IEC 62368-1 should be applied with reference to the Risk Reduction Measures contained in ISO/IEC Guide 51.

Illustration 3 - IEC62368-1 Safeguards Application (Product Design & Use)

In the illustration above, the:

• Left column gives a logical step-by-step approach to reducing risk, as defined in ISO/IEC Guide 51
• Middle column details the logic in IEC 62368-1 for how to protect users using different safeguards (NB Equipment Safeguard is highlighted because it is the primary content of IEC 62368-1)
• Right column gives examples of application with reference to clause 4.8 of IEC 62368-1, consumer remote controllers

To consider safeguards from the perspective of different Levels, the manufacturer must first categorize the different safeguards into two levels:

• Level 1: Basic Safeguard, Supplementary Safeguard
• Level 2: Double Safeguard, Reinforced Safeguard

Following this, IEC 62368-1 requires the manufacturer to consider safeguard levels as they apply to different types of user and energy source. This can be a complex topic but, for the purposes of this article, it can be simplified to the following simple rule:

• Users - three types: Skilled Person, Instructed Person and Ordinary Person
• Energy sources - three types: Class 1, Class 2 and Class 3

In the table below, the user is more vulnerable as they become less skilled (bottom to top) and energy sources become more dangerous as the class increases (left to right). Therefore, an ordinary person using a Class 3 product would require two levels of safeguard but a skilled person using a Class 1 product would not require a safeguard.

Illustration 4 - IEC62368-1 Safeguards Application (Energy Sources & Users)

The application of EN 62368-1 and UL 62368-1 will become mandatory in the EU and North America in December 2020. Because the logic behind IEC 62368-1 differs greatly from the safety standards it is replacing, manufacturers should now ensure they understand how the principles and safeguards enshrined in IEC 62368-1 can be applied to their products.

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For more information, please contact:

Dan Xie (谢丹)
Technical Manager - IT & AV & Battery
SGS
t: [phone]