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EN 62368 adopts a hazard-based approach to product safety
Technological innovation has seen the lines become increasingly blurred between previously distinct technologies. This change means that multimedia products often fall under both IEC 60065 (AV equipment) and IEC 60950-1 (IT equipment).
A new standard, IEC 62368‑1:2018 (audio/video, information and communication technology equipment, Part 1: safety requirements), was introduced to cover products that fall under these two standards, and will supersede both of them, worldwide.
IEC 62368 is applicable to the safety of electrical and electronic equipment and business and office machines with a rated voltage not exceeding 600V. According to the IEC: “This is a product safety standard that classifies energy sources, prescribes safeguards against those energy sources and provides guidance on the application of, and requirements for, those safeguards. The prescribed safeguards are intended to reduce the likelihood of pain, injury and, in the case of fire, property damage.”
EN 62368-1, the European version of IEC 62368, 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.
Manufacturers have been able to use it for the past four years, with early adoption giving them the opportunity to take advantage of the increased flexibility offered by the new standard.
Changing compliance dates
The date for the withdrawal of EN 60065 and EN 60950 was initially 20 June 2019, creating a mandatory requirement for all AV and information and communication technology (ICT) components and equipment in Europe to comply with EN 62368 after this date.
The European committee for electro‑technical standardisation (CenElec) and regulators in North America recently agreed a new date of 20 December 2020 to synchronise the date that both IEC 62368 and EN 62368 will replace the outgoing 60950-1 and 60065 standards. This will help to make compliance simpler for manufacturers, as both USA and EU standards will be harmonised simultaneously.
The EU has also extended the end date for existing products, which, having been previously tested against the two old standards, can now benefit from a presumption of conformity. Originally planned for 20 June 2019, this cessation of conformity has now also been set for 20 December 2020. This date extension by the EU and USA gives manufacturers more time to update their testing procedures and documentation.
After December 2020, EN/IEC 62368 will become mandatory under the requirements of the Low Voltage Directive and the Radio Equipment Directive, so there is a single date upon which they can focus compliance activities. Other countries and their local authorities will confirm their adoption schedules.
More than a merger
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. It has both differences in its structure and 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 defines hazard-based requirements, using engineering principles and taking into account relevant equipment standards and pilot documents.
This makes EN 62368-1 a technology‑independent safety standard that should provide more future‑proofing than its predecessors and introduce greater design freedoms, leading to the creation of safer products for end users.
New hazard-based approach
Hazard‑based safety engineering (HBSE) 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.
HBSE principles are intended to protect end users by identifying potentially hazardous energy sources and the mechanisms by which they may transfer energy to a user.
The scope of the standard’s requirements include both normal operation and fault conditions. It also requires that safeguards protect against pain or injury from electric shock or thermal burn injury, as well as prevent electrically‑caused fires.
The effectiveness of those safeguards must also be measured.
An energy source can be electric shock, electrically-caused fire, chemical (including batteries), mechanical (such as moving parts, sharp edges, physical stability), thermal energy source (skin burn) and radiation (ionising, non‑ionising or acoustic).
An HBSE approach means that manufacturers need no longer prove that prescribed specifications have been met, but it does require them to demonstrate that known hazards have been considered.
There must also be evidence that the product has been designed to be safe to use in the expected context. Even though this is a hazard-based approach, it does not require risk analysis.
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.
Energy sources
Unless otherwise specified, a Class 1 energy source is one with levels not exceeding Class 1 limits under normal operating conditions, 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. Under contact with a body part it may be detectable, but is not likely to cause injury.
A Class 2 energy source is one with levels exceeding Class 1 limits and not exceeding Class 2 limits under normal operating conditions, abnormal operating conditions, or single fault conditions. In contact with a body part it may cause pain, but is unlikely to cause injury.
The energy in a Class 3 source, in contact with a body part, can cause injury. It may cause ignition and the spread of flames where fuel is available.
New approach
EN 62368-1 introduces a completely new methodology, turning the established principles of EN 60065 and EN 60950 on their heads. This requires a new mindset when applying the standard. Product designers must also recognise that the new standards apply not only to the end product, but to major components and subsystems, such as power supplies.
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 moves us 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 individual engineers may not 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 early‑adopter manufacturers is that they have had plenty of time to become familiar with the new standard, and to adapt their design approaches. As technologies converge, products must rely on both their physical components and integrated software to function safely and reliably.
The new standard should provide greater flexibility in proving safe design, as it should be technology independent so it will better allow for the rapid pace of technological innovation and convergence.
We are moving towards the latter part of the transition period for 60950 and 60065 to be replaced by IEC/EN 62368, so it is vital that the fundamental concepts and the differences of this hazard-based standard approach are fully understood.
A typical three-step 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 whether 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 prevent this, and measure their effectiveness.
There is a hierarchy of safeguards, which can be applied, that must be taken into account.
Equipment safeguards, for example, do not require any knowledge or actions by persons coming into contact with the equipment.
For installation safeguards a safety characteristic can only be provided after installation. For example, the equipment has to be bolted to the floor to provide stability.
Behavioural safeguards are when the equipment requires an energy source to be accessible.
