Hazard-Based Safety Engineering (HBSE): The new standard UL-CSA-EN-IEC62368-1, the Standard for Audio/Video, Information and Communication Technology Equipment, was developed by IEC Technical Committee TC108 using a relatively new safety science discipline referred to as “Hazard-Based Safety Engineering”. The methods used to protect the user from harm are very similar to the “6 Hazards of Product Safety” approach of the previous standards UL-CSA-EN-IEC60950-1 and UL-CSA-EN-IEC60065-1 (see Whitepapers #30 – #37). However, the HBSE process begins with a broader view, evaluating all “energy sources” and the potential for each to cause “pain and injury” as well as their ability to ignite combustible materials.
The HBSE Process: The overall HBSE process within the new 62368 standard is fairly straightforward:
1) Identify all “energy sources” in the product.
2) Classify each of the energy sources in the product = Class 1, Class 2, or Class 3.
3) Identify “safeguards” used to protect the users from the energy sources capable of causing pain, injury, or damage per the requirements in the standard.
4) Verify that the safeguards comply with the test and construction requirements in the standard.
Energy Sources: The same type of hazards are considered in the new standard as with the old standards, they are just organized and titled differently. Under the title “Forms of Energy”, the new 62368 standard identifies these five possible energy sources:
A) Electrical Energy = electrical injuries
B) Thermal Energy = electrically-caused fire considerations as well as skin burns from contact
C) Chemical Reaction = exposure to hazardous chemicals
D) Kinetic Energy = injuries caused by movement from moving parts and from people in motion contacting equipment parts
E) Radiated Energy = energy that is radiated out from the product such as optical and acoustic energy
Energy Source Classification: Each of the five energy sources identified by the standard are divided into 3 classes based on their effect on the human body and their effect on combustible materials. It’s important to note that the standard is now in color and each of the class levels is color coded as shown below:
Safeguards: Once each energy source in the product has been identified and classified based on their hazard potential, the safeguards used to protect the users from these potentially hazardous energy sources are then identified and evaluated in accordance with the standard. The standard categorizes “safeguards” by type with construction and, in some cases, testing requirements provided for each:
a) Equipment Safeguard: An “equipment safeguard” is a safeguard that is an integral part of the product. This is the preferred type of safeguard since it does not require any knowledge or actions by the persons using or coming into contact with the product. For example, electrical insulation is considered an equipment safeguard. Equipment safeguards can serve as a “basic”, “supplementary”, “double”, or “reinforced” safeguard.
b) Installation Safeguard: An “installation safeguard” is a safety characteristic that can only be provided after installation of the product. For example, equipment that must be mounted in place to insure stability. Installation safeguards are considered a “supplementary” guard.
c) Personal Safeguard: A “personal safeguard” is a safety device worn on the body. Requirements for personal safeguards are not included in the standard. The standard assumes that the user will wear all personal safeguards instructed by the manufacturer.
d) Behavioral Safeguard: A “behavioral safeguard” is a voluntary or instructed behavior intended to reduce the likelihood of transfer of energy to a body part. There are three kinds of behavioral safeguards, each type applying to a specific kind of user (see Weekly Whitepaper # 93):
1. Instructional Safeguards are intended for an “ordinary” person, but may also be addressed to an “instructed” or “skilled” person.
2. Precautionary Safeguards are used by an “instructed” person.
3. Skill Safeguards are used by a “skilled” person.
Summary: The new standard identifies five different energy sources that have the potential to cause a hazard to the user. Each of the energy sources within a product are divided into 3 “class” levels depending on the level of pain, injury, and their ability to cause ignition of combustible materials. Safeguards are used to protect the user from Class 2 and Class 3 energy sources (hazards). As with the previous standards, higher hazard levels require two levels of protection (double or reinforced safeguards). And as with previous standards, much of the requirements in the new 62368 standard involve requirements used to evaluate repeatability and reliability of the needed safeguards (levels of protection). This is similar to the previous standards but confusingly different terminology.
We will continue to publish additional whitepapers over the coming weeks to help everyone understand the new 62368 standard – providing details on each of the energy sources, the class level limits for each energy source, and the safeguard requirements for each.
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