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A new, hazard-based approach to product safety standards

21 December 2018

Clare Gittens of TÜV SÜD Product Service looks at EN 62368-1, which sees us move from a prescriptive and objective method of proving compliance to a more subjective approach, which relies on engineering expertise to identify potential hazards.

As technologies converge, products must rely on both their physical components and integrated software to function safely and reliably. This change means that multi-media products are increasingly falling under both IEC 60065 (AV equipment) and IEC 60950-1 (IT equipment). A new standard, IEC 62368 (Audio/video, information and communication technology equipment - Part 1: Safety requirements), has therefore been introduced, which covers products that fall under these two previously separate standards.

The European version of IEC 62368, EN 62368-1, was adopted in 2014. As the new EN 62368-1 represented a significant departure from traditional standards, it was initially introduced as a voluntary alternative to the existing standards. So, manufacturers have been able to use it for four years, with early adoption giving them the opportunity to take advantage of the increased flexibility offered by the new standard.

The date of withdrawal for the EN 60065 and EN 60950 standards was originally only six months away (June 20, 2019), meaning that after this date compliance with EN 62368 would be mandatory for all audio-visual (AV) and information and communication technology (ICT) components and equipment in Europe. However, the European committee for electro technical standardisation (CENELEC) and regulators in North America recently agreed on a new date (20 December 2020) to harmonise the date that both IEC 62368 and EN 62368 will replace the outgoing 60950-1 and 60065 standards.

After this date, EN/IEC 62368 will become mandatory under the requirements of the Low Voltage Directive and the Radio Equipment Directive. This gives manufacturers which supply the global market a single, unified date on which they can focus their compliance activities. Other countries and their local authorities will confirm their adoption schedule.

EN 62368 is not simply a merger of the two old standards. While it still contains some of the same specific requirements and compliance criteria as its predecessors, it follows a different methodology.

Not only does it have limited similarity in its structure, it is the first time that a hazard-based approach has been taken to product safety.

The previous standards, 60950-1 and 60065, closely dictated product design and were known as ‘prescriptive’ standards. The new philosophy applied has been to define hazard-based requirements, using engineering principles and taking into account relevant equipment standards and pilot documents. To a large extent this makes EN 62368-1 a technology-independent safety standard, which introduces greater design freedom.

Hazard-Based Safety Engineering

The hazard-based approach HBSE (Hazard-Based Safety Engineering) was used as a principal methodology in developing EN 62368-1, which defines a hazard as an energy source that exceeds the body susceptibility limits.

An energy source can be:
• Electric shock energy source
• Electrically-caused fire energy source
• Chemical energy source (e.g., chemicals, including batteries)
• Mechanical energy source (e.g., moving parts, sharp edges, physical stability)
• Thermal energy source (e.g., skin burn)
• Radiation energy source (e.g., ionizing, non-ionizing, acoustic)

While EN 60065 and EN 60950-1 follow a set of rules and criteria outlined in both standards, EN 62368-1 requires the identification of safety hazards in the early product development phase so that subsequent product design eliminates them. It also provides more performance options to demonstrate compliance.

The following is a typical example of the Hazard Based Approach:
• Identify the energy sources by reviewing the product and its associated schematics.
• Take measurements to determine the energy levels (Class 1, 2, or 3) and identify if the sources are hazardous.
• If they are hazardous, identify the means by which energy can be transferred to a body part and design the safeguards that will stop this and measure their effectiveness.

There is also a hierarchy of safeguards that must be taken into account:
1. Equipment safeguards - do not require any knowledge or actions by persons coming into contact with the equipment.
2. Installation safeguards - when a safety characteristic can only be provided after installation. For example, the equipment has to be bolted to the floor to provide stability.
3. Behavioural safeguards - when the equipment requires an energy source to be accessible.

Source identification

Unless otherwise specified, a Class 1 source is an energy source with levels not exceeding class 1 limits under:
• normal operating conditions; and
• abnormal operating conditions that do not lead to a single fault condition; and
• single fault conditions that do not result in class 2 limits being exceeded.

A class 1 energy source, under contact with a body part, may be detectable, but is not likely to cause injury. A Class 2 source is an energy source with levels exceeding Class 1 limits and not exceeding Class 2 limits under normal operating conditions, abnormal operating conditions, or single fault conditions. Under contact with a body part, a Class 2 energy source may be painful, but is not likely to cause an injury. However, the energy in a Class 3 source, under contact with a body part, is capable of causing injury. For fire, the energy in a Class 3 source may cause ignition and the spread of flames where fuel is available.

A complete change

EN 62368-1 introduces a completely new methodology, turning on its head the well-established and understood principles of EN 60065 and EN 60950, and requires a new mind-set when applying the standard.

The prescriptive test-based approach of the old standards leaves little room for subjectivity, as they require engineers to apply specific tests to prove compliance. The introduction of EN 62368 sees us move from an objective method of proving compliance to a more subjective approach, which relies on engineering expertise to identify potential hazards. However, ‘to err is human’ and not every individual engineer may identify exactly the same hazards when considering a similar product. Only time will tell if this new, more flexible, less objective approach ensures that products remain safe.

The advantage for any manufacturers that were early adopters is that they have had plenty of time to become familiar with the new standard, and adapt design approaches accordingly. The new standard should provide greater flexibility in proving safe design, it should be technology independent and should better allow for technology advancement.

About the author

Clare Gittens is Business Line Manager, Consumer Product Service at TÜV SÜD Product Service and has a decade of experience in customer relations management. Her primary areas of technical expertise include the Radio Equipment Directive and Low Voltage Directive, as well as issues surrounding the electromagnetic capability of products.

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