IEC 62368-1 - New hazard-based standard approach
Due to technology convergence, the same multi-media products are increasingly falling under two safety standards - IEC 60065 (audio, video and similar electronic apparatus) and IEC 60950-1 (information technology equipment). IEC Technical Committee (TC) 108 has therefore created a new ‘hazard-based’ standard, which would cover both.
Consequently, IEC 62368-1 (Audio/video, information and communication technology equipment - Part 1: Safety requirements) was published in January 2010. Although the new standard covers products that fall under IEC 60065 and IEC 60950-1, this is not a simple merger of them, but is entirely new and has no similarity in its structure to the two standards that it is intended to replace.
This is the first time that a hazard-based, approach has been taken to product safety and it is important to recognise at this point that risk assessment and risk management does not form part of the new standard, rather it still contains specific requirements and compliance criteria but follows a different methodology. The basic process being to identify and classify energy sources in the product, identify safeguards required for protection and then qualify the effectiveness of those safeguards.
As the new IEC 62368-1 represents a significant departure from traditional standards, it has initially been introduced as a voluntary alternative to the existing standards, but is expected to be fully adopted in the next few years. It may now be followed by electronics manufacturers in their safety testing process instead of the two older standards, with early adoption giving them the opportunity to take advantage of the increased flexibility offered by the new standard.
The hazard-based approach
HBSE (Hazard-based Safety Engineering) was used as a principal methodology in developing IEC 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)
The philosophy applied has been to define hazard-based requirements, using engineering principles and taking into account relevant IEC
equipment standards and pilot documents. To a large extent this makes IEC 62368-1 a technology independent safety standard allowing for more design freedom.
IEC 60065 and IEC 60950-1 follow a set of rules outlined in both standards. IEC 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.
- 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, design the safeguards that will stop this and measure their effectiveness.
There is also a hierarchy of safeguards, which can be applied, that must be taken into account:
Equipment safeguards - do not require any knowledge or actions by persons coming into contact withthe equipment.
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.
Behavioural safeguards - when the equipment requires an energy source to be accessible.
Classes of energy source
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.
To err is human
IEC TC 108 considers that the new standard is no different to the legacy standards IEC 60065 and IEC 60950-1, as it is a complete product safety standard with specific requirements and compliance criteria. However, IEC 62368-1 introduces a completely new methodology, turning on its head the well-established and understood principles of IEC 60065 and IEC 60950 and requires a new mind-set when applying the standard.
The new standard should provide greater flexibility in proving safe design, it should be technology independent and should better allow for technology advancement. But are you prepared for what is in effect a fundamental change in how to demonstrate product safety compliance?