IEC TR 62368-2:2015
(Main)Audio/video, information and communication technology equipment - Part 2: Explanatory information related to IEC 62368-1
Audio/video, information and communication technology equipment - Part 2: Explanatory information related to IEC 62368-1
IEC/TR 62368-2:2015(E) provides explanatory information related to IEC 62368-1. Only those subclauses considered to need further background reference information or explanation of their content to benefit the reader are included. Therefore, not all numbered subclauses are cited. Unless otherwise noted, all references are to clauses, subclauses, annexes, figures or tables located in IEC 62368-1:2014. This second edition cancels and replaces the first edition published in 2011. It constitutes a technical revision. This second edition updates the first edition of IEC 62368-2 published in 2011 to take into account changes made to IEC 62368-1:2010 as identified in the Forword of IEC 62368-1:2014. This Technical Report is informative only. In case of a conflict between IEC 62368-1 and IEC TR 62368-2, the requirements in IEC 62368-1 prevail over this Technical Report. Key words: Audio/Video, Safeguards, Information, Communication
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IEC TR 62368-2
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Edition 2.0 2015-02
TECHNICAL
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Audio/video, information and communication technology equipment –
Part 2: Explanatory information related to IEC 62368-1
IEC TR 62368-2:2015-02(en)
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IEC TR 62368-2
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Audio/video, information and communication technology equipment –
Part 2: Explanatory information related to IEC 62368-1
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AUDIO/VIDEO, INFORMATION AND
COMMUNICATION TECHNOLOGY EQUIPMENT –
Part 2: Explanatory information related to IEC 62368-1:2014
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62368-2, which is a technical report, has been prepared by subcommittee TC 108: Safety
of electronic equipment within the field of audio/video, information technology and
communication technology.
This second edition cancels and replaces the first edition published in 2011. This edition
constitutes a technical revision.
This second edition updates the first edition of IEC 62368-2 published in 2011 to take into
account changes made to IEC 62368-1:2010 as identified in the Foreword of IEC 62368-
1:2014.
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IEC TR 62368-2:2015 © IEC 2015 – 3 –
This Technical Report is informative only. In case of a conflict between IEC 62368-1 and
IEC TR 62368-2, the requirements in IEC 62368-1 prevail over this Technical Report.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
108/540/DTR 108/553/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
In this standard, the following print types are used:
– notes/explanatory matter: in smaller roman type;
– tables and figures that are included in the rationale have linked fields (shaded in grey if
“field shading” is active).
In this standard, "HBSDT" stands for Hazard Based Standard Development Team, which is
the Working Group of TC 108 responsible for the development and maintenance of IEC
62368-1.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62368 series can be found, under the general title Audio/video,
information and communication technology equipment, on the IEC website.
In this document, only those subclauses considered to need further background reference
information or explanation of their content to benefit the reader are included. Therefore, not
all numbered subclauses are cited. Unless otherwise noted, all references are to clauses,
subclauses, annexes, figures or tables are located in IEC 62368-1:2014.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
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AUDIO/VIDEO, INFORMATION AND
COMMUNICATION TECHNOLOGY EQUIPMENT –
Part 2: Explanatory information related to IEC 62368-1:2014
Clause 0 Principles of this product safety standard
Clause 0 is informational and provides a rationale for the normative clauses of
the standard.
0.5.1 General
ISO IEC Guide 51:2014, 6.3.5 states:
“When reducing risks the order of priority shall be as follows:
a) inherently safe design;
b) guards and protective devices;
c) information for end users.
Inherently safe design measures are the first and most important step in the
risk reduction process. This is because protective measures inherent to the
characteristics of the product or system are likely to remain effective,
whereas experience has shown that even well-designed guards and
protective devices can fail or be violated and information for use might not
be followed.
Guards and protective devices shall be used whenever an inherently safe
design measure does not reasonably make it possible either to remove
hazards or to sufficiently reduce risks. Complementary protective measures
involving additional equipment (for example, emergency stop equipment)
might have to be implemented.
The end user has a role to play in the risk reduction procedure by complying
with the information provided by the designer/supplier. However, information
for use shall not be a substitute for the correct application of inherently safe
design measures, guards or complementary protective measures.”
In general, this principle is used in IEC 62368-1. The table below shows a
comparison between the hierarchy required in ISO IEC Guide 51 and the
hierarchy used in IEC 62368-1:2014:
ISO IEC Guide 51 IEC 62368-1
a) inherently safe design 1. inherently safe design by limiting all energy
hazards to class 1
b) guards and protective devices 2. equipment safeguards
3. installation safeguards
c) information for end users 4. behavioral safeguards
5. instructional safeguards
0.5.7 Equipment safeguards during skilled person service conditions
Purpose: To explain the intent of requirements for providing safeguards against
involuntary reaction.
Rationale: By definition, a skilled person has the education and experience to identify all
class 3 energy sources to which he may be exposed. However, while servicing
one class 3 energy source in one location, a skilled person may be exposed to
another class 3 energy source in a different location.
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In such a situation, either of two events is possible. First, something may cause
an involuntary reaction of the skilled person with the consequences of contact
with the class 3 energy source in the different location. Second, the space in
which the skilled person is located may be small and cramped, and inadvertent
contact with a class 3 energy source in the different location may be likely.
In such situations, this standard may require an equipment safeguard solely for
the protection of a skilled person while performing servicing activity.
___________
Clause 1 Scope
Purpose: To identify the purpose and applicability of this standard and the exclusions
from the scope.
Rationale: The scope excludes requirements for functional safety. Functional safety is
addressed in IEC 61508-1. Because the scope includes computers that may
control safety systems, functional safety requirements would necessarily
include requirements for computer processes and software.
___________
Clause 2 Normative references
The list of normative references is a list of all documents that have a normative
reference to it in the body of the standard. As such, referenced documents are
indispensable for the application of this standard. For dated references, only
the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
Recently, there were some issues with test houses that wanted to use the
latest edition as soon as it was published. As this creates serious problems for
manufacturers, since they have no chance to prepare, it was felt that a
reasonable transition period should be taken into account. This is in line with
earlier decisions taken by the SMB that allow transition periods to be
mentioned in the foreword of the standards. Therefore TC 108 decided to
indicate this in the introduction of the normative references clause, to instruct
test houses to take into account any transition period, effective date or date of
withdrawal established for the document.
These documents are referenced, in whole, in part or as alternative
requirements to the requirements contained in this standard. Their use is
specified, where necessary, for the application of the requirements of this
standard.
___________
Clause 3 Terms, definitions and abbreviations
Rationale is provided for definitions that deviate from IEC 60050 definitions or
from pilot standard definitions.
3.3.2.1 electrical enclosure
Source: IEC 60050-195:1998, 195-06-13
Purpose: To support the concept of safeguards as used in this standard.
Rationale: The definition is modified to use the term “safeguard” in place of the word
“protection”. The word “safeguard” identifies a physical “thing” whereas the
word “protection” identifies the act of protecting. This standard sets forth
requirements for use of physical safeguards and requirements for those
safeguards. The safeguards provide “protection” against injury from the
equipment.
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3.3.5.1 basic insulation
Source: IEC 60050-195:1998,195-06-06
Purpose: To support the concept of safeguards as used in this standard.
Rationale: The definition is modified to use the term “safeguard” in place of the word
“protection”. The word “safeguard” identifies a physical “thing” whereas the
word “protection” identifies the act of protecting. This standard sets forth
requirements for use of physical safeguards and requirements for those
safeguards. The safeguards provide “protection” against injury from the
equipment.
3.3.5.2 double insulation
Source: IEC 60050-195:1998,195-06-08
Purpose: To support the concept of safeguards as used in this standard.
Rationale: See 3.3.5.1, basic insulation.
3.3.5.5 solid insulation
Source: IEC 60664-1:2007, 3.4
Purpose: To support the concept that safeguards are interposed between an energy
source and a body part.
Rationale: IEC 60664-1 defines insulation as material interposed between two conductive
parts. The IEC 60664-1 definition is modified by adding that insulation is also
“between a conductive part and a body part.” For safety purposes, solid
insulation is not only used between conductors, but is also used between a
conductor and a body part. For example, a Class II equipment employs solid
insulation in this manner.
3.3.5.6 supplementary insulation
Source: IEC 60050-195:1998, 195-06-07
Purpose: To support the concept of safeguards as used in this standard.
Rationale: See 3.3.5.1, basic insulation.
3.3.6.7 restricted access area
Source: IEC 60050-195:1998, 195-04-04
Purpose: To use the concept of “instructed persons” and “skilled persons” as used in this
standard.
Rationale: The definition is modified to use the terms “instructed persons” and “skilled
persons” rather than “electrically instructed persons” and “electrically skilled
persons.”
3.3.7.8 reasonably foreseeable misuse
Source: ISO IEC Guide 51:2014, definition 3.14
Rationale: Misuse depends on personal objectives, personal perception of the equipment,
and the possible use of the equipment (in a manner not intended by the
manufacturer) to accomplish those personal objectives. Equipment within the
scope of this standard ranges from small handheld equipment to large,
permanently installed equipment. There is no commonality among the
equipment for readily predicting human behaviour leading to misuse of the
equipment and resultant injury. Where a possible reasonably foreseeable
misuse that may lead to an injury is not covered by the requirements of the
standard, manufacturers are encouraged to consider reasonably foreseeable
misuse of equipment and provide safeguards, as applicable, to prevent injury in
the event of such misuse. (Not all reasonably foreseeable misuse of equipment
results in injury or potential for injury.)
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3.3.8.1 instructed person
Source: IEC 60050-826:2004, 826-18-02
Rationale: The definition is modified to use the terms “energy sources”, “skilled person”,
and “precautionary safeguard”. The definition is made stronger by using the
term “instructed” rather than “advised”.
3.3.8.3 skilled person
Source: IEC 60050-826:2004, 826-18-01
Rationale: The definition is modified to use the phrase “to reduce the likelihood of”.
IEC 62368-1 does not use the word “hazard”.
3.3.14.4 prospective touch voltage
Source: IEC 60050-195:1998, 195-05-09
Purpose: To properly identify electric shock energy source voltages.
Rationale: The definition is modified to delete “animal”. The word “person” is also deleted
as all of the requirements in the standard are with respect to persons.
3.3.14.9 working voltage
Source: IEC 60664-1:2007, definition 3.5
Purpose: To distinguish between r.m.s. working voltage and peak working voltage.
Rationale: The IEC 60664-1 definition is modified to delete “r.m.s”. IEC 62368-1 uses both
r.m.s. working voltage and peak working voltage; each term is defined.
3.3.15.2 class II construction
Source: IEC 60335-1:2010, 3.3.11
Purpose: Although the term is not used in the standard, for completeness, it was decided
to retain this definition.
Rationale: The word “appliance” is changed to “equipment”.
____________
Clause 4 General requirements
Purpose: To explain how to investigate and determine whether or not safety is involved.
Rationale: In order to establish whether or not safety is involved, the circuits and
construction are investigated to determine whether the consequences of
possible fault conditions would lead to an injury. Safety is involved if, as a
result of a single fault condition, the consequences of the fault lead to a risk of
injury.
If a fault condition should lead to a risk of injury, the part, material, or device
whose fault was simulated may comprise a safeguard.
Rationale is provided for questions regarding the omission of some traditional
requirements appearing in other safety standards. Rationale is also provided
for further explanation of new concepts and requirements in this standard.
Reasonable foreseeable misuse
Rationale: Apart from Annex M, this standard does not specifically mention foreseeable
misuse. Nevertheless, the requirements of the standard cover many kinds of
foreseeable misuse, such as covering of ventilation openings, paper jams,
stalled motors etc.
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functional insulation
Rationale: This standard does not include requirements for functional insulation. By its
nature, functional insulation does not provide a safeguard function against
electric shock or electrically-caused fire and therefore may be faulted.
Obviously, not all functional insulations are faulted as this would be
prohibitively time-consuming. Sites for functional insulation faults should be
based upon physical examination of the equipment, and upon the electrical
schematic.
Note that basic and reinforced insulation may also serve as functional
insulation, in which case the insulation is not faulted.
functional components
Rationale: This standard does not include requirements for functional components. By
their nature, individual functional components do not provide a safeguard
function against electric shock, electrically-caused fire, thermal injury, etc., and
therefore may be candidates for fault testing. Obviously, not all functional
components are faulted as this would be prohibitively time-consuming.
Candidate components for fault testing should be based upon physical
examination of the equipment, upon the electrical schematic diagrams, and
whether a fault of that component might result in conditions for electric shock,
conditions for ignition and propagation of fire, conditions for thermal injury, etc.
As with all single fault condition testing (Clause B.4), upon faulting of a
functional component, there shall not be any safety consequence (for example,
a benign consequence), or a basic, supplementary, or reinforced safeguard
shall remain effective.
In some cases, a pair of functional components may comprise a safeguard. If
the fault of one of the components in the pair is mitigated by the second
component, then the pair is designated as a double safeguard. For example, if
two diodes are employed in series to protect a battery from reverse charge,
then the pair comprises a double safeguard and the components should be
limited to the manufacturer and part number actually tested. A second example
is that of an X-capacitor and discharge resistor. If the discharge resistor should
fail open, then the X-capacitor will not be discharged. Therefore, the X-
capacitor value is not to exceed the ES2 limits specified for a charged
capacitor. Again, the two components comprise a double safeguard and the
values of each component are limited to values for ES1 under normal operating
conditions and the values for ES2 under single fault conditions.
4.1.1 Application of requirements and acceptance of materials, components
and subassemblies
Purpose: To accept components as safeguards.
Rationale: This standard includes requirements for safeguard components. A safeguard
component is a component specifically designed and manufactured for both
functional and safeguard parameters. Examples of safeguard components are
capacitors complying with IEC 60384-14 and other IEC component standards.
Acceptance of components and component requirements from IEC 60065
and IEC 60950-1
Purpose: To accept both components and sub-assemblies investigated to the legacy
standards, IEC 60065 and IEC 60950-1, and components complying with
individual component requirements within these standards during the transition
period.
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Rationale: To facilitate a smooth transition from the legacy standards IEC 60065 and
IEC 60950-1 to IEC 62368-1, including by the component supply chain, this
standard allows for acceptance of both components and sub-assemblies
investigated to the legacy standards. Individual component requirements within
these standards may be used for compliance with IEC 62368-1 without further
investigation, other than to give consideration to the appropriate use of the
component or sub-assembly in the end-product.
This means, for example, if a switch mode power supply is certified to
IEC 60065 or IEC 60950-1, this component can be used in equipment
evaluated to IEC 62368-1 without further investigation, other than to give
consideration to the appropriate use of the component, such as use within its
electrical ratings.
This also means, for example, since IEC 60950-1 allows for wiring and cables
insulated with PVC, TFE, PTFE, FEP, polychloroprene or polyimide to comply
with material requirements for parts within a fire enclosure without need for the
application of a flammability test, the same wire can be used to comply with the
requirements in 6.5.2 for insulation on wiring used in PS2 or PS3 circuits and
without the need for application of a flammability test per IEC 60332 series or
IEC TS 60695-11-21 as normally is required by 6.5.1.
It is important to note that this will only be allowed during the transition
period from the legacy standards to IEC 62368-1.
4.2.1 Class 1 energy source
A class 1 energy source is a source that is expected not to create any pain or
injury. Therefore, a class 1 energy source may be accessible by any person.
Under some specific conditions of abnormal operation or single fault, a class 1
energy source may reach class 2 limits. However, this source still remains a
class 1 energy source. In this case, an instructional safeguard may be
required.
4.2.2 Class 2 energy source
A class 2 energy source is a source that may create pain, but which is unlikely
to create any serious injury. Therefore, a class 2 energy source may not be
accessible by an ordinary person. However, a class 2 energy source may be
accessible by:
- an instructed person; and
- a skilled person.
4.2.3 Class 3 energy source
A class 3 energy source is a source that is likely to create an injury. Therefore
a class 3 energy source may not be accessible to an ordinary person or an
instructed person. A class 3 energy source may, in general, be accessible to a
skilled person.
Any source may be declared a class 3 energy source without measurement, in
which case all of the safeguards applicable to class 3 are required.
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4.3.2 Safeguards for protection of an ordinary person
IEC
4.3.3 Safeguards for protection of an instructed person
IEC
4.3.4 Safeguards for protection of a skilled person
IEC
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Table 1 – General summary of required safeguards
Number of safeguards required to be interposed between an
energy source and a person
Person
Class 1 Class 2 Class3
Ordinary person 0 1 2
Instructed person 0 0 2
Skilled person
0 0 0 or 1
Table 1 gives a general overview of the required number of safeguards
depending on the energy source and the person to whom the energy source is
accessible. The different clauses have requirements that sometimes deviate
from the general principle as given above. These cases are clearly defined in
the requirements sections of the standard.
For a skilled person, there is normally no safeguard required for a class 3
energy source. However, if there are multiple class 3 energy sources
accessible or if the energy source is not obvious, a safeguard may be required.
4.4.2 Composition of a safeguard
Purpose: To specify design and construction criteria for a single safeguard (basic,
supplementary, or reinforced) comprised of more than one element, for
example, a component or a device.
Rationale: Safeguards need not be a single, homogeneous component. Indeed, some
parts of this standard require a single safeguard be comprised of two or more
elements. For example, for thin insulation, two or more layers are required to
qualify as supplementary insulation. Another example is protective bonding and
protective earthing, both of which are comprised of wires, terminals, screws,
etc.
If a safeguard is comprised of two or more elements, then the function of the
safeguard should not be compromised by a failure of any one element. For
example, if a screw attaching a protective earthin
...
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