IEC TR 62102:2005

TECHNICAL IEC
REPORT TR 62102
Second edition
2005-05
Electrical safety –
Classification of interfaces for equipment
to be connected to information and
communications technology networks

Reference number
IEC/TR 62102:2005(E)
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TECHNICAL IEC
REPORT TR 62102
Second edition
2005-05
Electrical safety –
Classification of interfaces for equipment
to be connected to information and
communications technology networks

 IEC 2005  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
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– 2 – TR 62102  IEC:2005(E)
CONTENTS
FOREWORD.3
INTRODUCTION.5

1 Scope.6
2 Normative references.6
3 Terms and definitions .7
3.1 Definitions from IEC 60950-1 .7
3.2 Definitions from IEC 60950-21 .9
3.3 Additional definitions for this document .9
3.4 Abbreviations.10
4 Reference configuration.10
5 Safety categories of interfaces provided for connection to an information and
communications technology network .13
5.1 SELV circuits.13
5.2 TNV circuits.13
5.3 User information .13
5.4 RFT circuits.13
6 Phenomena affecting the safety of interface ports .13
6.1 Network Environment 0.14
6.2 Network Environment 1.14
7 Determination of circuit type.15

Annex A (informative) Consideration of interface phenomenon .16
Annex B (informative) Worked examples of certain network interfaces.19
Annex C (informative) Conditions for Network Environment 0.22
Annex D (informative) Voltage ranges of SELV circuits and TNV circuits.23

Bibliography .24

TR 62102  IEC:2005(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTRICAL SAFETY –
CLASSIFICATION OF INTERFACES FOR EQUIPMENT
TO BE CONNECTED TO INFORMATION AND
COMMUNICATIONS TECHNOLOGY NETWORKS

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,
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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 62102, which is a technical report, was prepared by IEC technical committee 108: Safety
of electronic equipment within the field of audio/video, information technology and
communication technology, previously organized as IEC technical committee 74: Safety and
energy efficiency of IT equipment.
This second edition cancels and replaces the first edition published in 2001. This edition
constitutes a technical revision. The principal changes in this edition as compared with the first
edition of IEC 62102 are as follows (small changes are not listed):
− this 2nd edition was updated to accord with IEC 60950-1:2001;
− RFT (remote feeding telecommunication) circuits from IEC 60950-21 have been added;

– 4 – TR 62102  IEC:2005(E)
− in Annex B more interfaces have been added;
− in Annex B the category of xDSL interfaces have replaced ADSL interfaces.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
108/128/DTR 108/130/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
Terms printed in bold in the text are defined in Clause 3.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result 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 document may be published at a later date.

TR 62102  IEC:2005(E) – 5 –
INTRODUCTION
This technical report is a guide to the determination of the interface requirements for
equipment in terms of safety. It lists a number of interfaces and indicates the safety category of
each listed interface. This technical report does not contain sufficient detail for conformance
testing purposes, except when used in conjunction with product standards such as
IEC 60950-1 and IEC 60950-21.
The equipment safety standards IEC 60950-1 and IEC 60950-21 specify the requirements for
categories of circuits as SELV circuits, TNV circuits, RFT circuits and hazardous voltage
circuits (among others). For stand-alone equipment it is a relatively simple matter to determine
the different categories of circuits. However, an equipment which has data port interfaces is
intended to be connected to other equipment, either locally or via a network. In this case, the
safety categories of the interfaces which will be connected together have to be compatible with
each other. Furthermore, the category of the interface of the remote equipment may be
unknown. This is the case in systems where telecommunication equipment and data
processing equipment are connected together via different types of interfaces and networks.
To overcome this situation it is necessary to classify the interfaces of equipment in such
configurations according to the application and to select the safety category for the interfaces
of the equipment and for the type of the network. Similarly, the interfaces have to be classified
for protection against damage of the equipment and of the network. Aspects of protection are
dealt with in the ITU-T K series of recommendations.

– 6 – TR 62102  IEC:2005(E)
ELECTRICAL SAFETY –
CLASSIFICATION OF INTERFACES FOR EQUIPMENT
TO BE CONNECTED TO INFORMATION AND
COMMUNICATIONS TECHNOLOGY NETWORKS

1 Scope
This technical report applies to equipment interfaces. These interfaces within the equipment
may be connected to telecommunication networks, may form part of the telecommunication
network infrastructure or may provide localized transfer of data. This technical report provides
guidance on the classification of interfaces in accordance with the circuit types defined in
IEC 60950-1 and IEC 60950-21 following an analysis of the telecommunication network
characteristics.
This technical report only covers equipment appropriately interconnected. Furthermore, it does
not address damage caused by one equipment to another equipment to which it is connected.
Exceptionally, interfaces may be designed for higher or lower levels for special applications. In
such cases it should be ensured that only interfaces having the same safety category and
protection level are connected together. This is based on the available specifications of the
equipment manufacturers and network providers, and on information regarding the installation
category of the mains interface.
This technical report is intended to be used by equipment designers, network operators,
network regulators/authorities, standards writers and network installers. It is applicable to
various interfaces of equipment. Network presentations are not equipment and so are not
covered by IEC 60950-1 and IEC 60950-21; hence they are also not covered by this technical
report. However, it is necessary to consider the characteristics, installation and presentation of
telecommunication networks when determining what equipment interface requirements apply
(for example, SELV circuit, TNV-1 circuit, TNV-2 circuit, TNV-3 circuit etc.).
If a standard other than IEC 60950-1 or IEC 60950-21 is used for designing the equipment and
its interface (for example, IEC 62151 in conjunction with other product safety standards), then
the corresponding requirements of these other standards are to be preferred.
If there is a conflict between this technical report and a more detailed specification, the latter
prevails.
This technical report applies regardless of ownership or responsibility for installation and
maintenance of the equipment or network.
NOTE Terminal equipment is often connected to customer premises cabling when used in a business
environment, and there are standards covering such cabling.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60950-1:2001, Information technology equipment – Safety – Part 1: General requirements
IEC 60950-21:2002, Information technology equipment – Safety – Part 21: Remote power
feeding
TR 62102  IEC:2005(E) – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Definitions from IEC 60950-1
3.1.1
a.c. mains supply
a.c. power distribution system external to the equipment for supplying power to a.c. powered
equipment. These power sources include public or private utilities and, unless otherwise
specified in the standard, equivalent sources such as motor-driven generators and
uninterruptible power supplies
[IEC 60950-1, definition 1.2.8.1]
3.1.2
hazardous voltage
voltage exceeding 42,4 V peak, or 60 V d.c., existing in a circuit which does not meet the
requirements for either a limited current circuit or a TNV circuit
[IEC 60950-1, definition 1.2.8.5]
3.1.3
limited current circuit
circuit which is so designed and protected that, under both normal operating conditions and
single fault conditions, the current which can be drawn is not hazardous
[IEC 60950-1, definition 1.2.8.8]
3.1.4
primary circuit
circuit which is directly connected to the a.c. mains supply. It includes, for example, the
means for connection to the a.c. mains supply, the primary windings of transformers, motors
and other loading devices
[IEC 60950-1, definition 1.2.8.3]
3.1.5
secondary circuit
circuit which has no direct connection to a primary circuit and derives its power from a
transformer, converter or equivalent isolation device, or from a battery
[IEC 60950-1, definition 1.2.8.4]
3.1.6
SELV circuit
secondary circuit which is so designed and protected that under normal operating conditions
and single fault conditions, its voltages do not exceed a safe value
[IEC 60950-1, definition 1.2.8.7]
3.1.7
TNV circuit (including TNV-1 circuit, TNV-2 circuit, TNV-3 circuit)
circuit that is in the equipment and to which the accessible area of contact is limited and that is
so designed and protected that, under normal operating conditions and single fault conditions,
the voltages do not exceed specified limit values
[IEC 60950-1, definition 1.2.8.10]

– 8 – TR 62102  IEC:2005(E)
3.1.8
telecommunication network
metallically terminated transmission medium intended for communication between equipment
that may be located in separate buildings, excluding:
– the mains system for supply, transmission and distribution of electrical power, if used as a
telecommunication transmission medium;
– cable distribution systems;
– SELV circuits connecting units of data processing equipment
NOTE 1 The term telecommunication network is defined in terms of its functionality, not its electrical
characteristics. A telecommunication network is not itself defined as being either an SELV circuit or a TNV
circuit. Only the circuits in the equipment are so classified.
NOTE 2 A telecommunication network may be:
– publicly or privately owned;
– subject to transient overvoltages due to atmospheric discharges and faults in power distribution systems;
– subject to longitudinal (common mode) voltages induced from nearby power lines or electric traction lines.
NOTE 3 Examples of telecommunication networks are:
– a public switched telephone network;
– a public data network;
– an Integrated Services Digital Network (ISDN);
– a private network with electrical interface characteristics similar to the above.
[IEC 60950-1, definition 1.2.13.8]
3.1.9
cable distribution system
metallically terminated transmission medium using coaxial cable, mainly intended for
transmission of video and/or audio signals between separate buildings or between outdoor
antennas and buildings, excluding:
– the mains system for supply, transmission and distribution of electric power, if used as a
communication transmission medium;
– telecommunication networks;
– SELV circuits connecting units of information technology equipment
NOTE 1 Examples of cable distribution systems are:
– local area cable networks, community antenna television systems and master antenna television systems
providing video and audio signal distribution;
– outdoor antennas including satellite dishes, receiving antennas, and other similar devices.
NOTE 2 Cable distribution systems may be subjected to greater transients than telecommunication networks.
[IEC 60950-1, definition 1.2.13.14]
3.1.10
service person
person having appropriate technical training and experience necessary to be aware of hazards
to which that person may be exposed in performing a task and of measures to minimize the
risks to that person or other persons
[IEC 60950-1, definition 1.2.13.5]
3.1.11
user
any person, other than a service person
[IEC 60950-1, definition 1.2.13.6]

TR 62102  IEC:2005(E) – 9 –
3.2 Definitions from IEC 60950-21
3.2.1
RFT circuit
remote feeding telecommunication circuit
a secondary circuit within the equipment, intended to supply or receive d.c. power via a
telecommunication network at voltages equal to or exceeding the limits for TNV circuits, and
on which overvoltages from telecommunication networks are possible
[IEC 60950-1, definition 3.1]
3.2.2
RFT-C circuit
an RFT circuit which is so designed and protected that under normal operating conditions and
single fault conditions, the currents in the circuit do not exceed defined values
[IEC 60950-1, definition 3.2]
3.2.3
RFT-V circuit
an RFT circuit which is so designed and protected that under normal operating conditions and
single fault conditions the voltages are limited and the accessible area of contact is limited
[IEC 60950-1, definition 3.3]
3.3 Additional definitions for this document
3.3.1
antenna interface
a port for connection of a radio frequency antenna to equipment
3.3.2
coaxial cable interface
a port for connection of a coaxial cable providing for asymmetrical transmission to equipment
NOTE In this technical report the use of both indoor and outdoor coaxial cables is considered separately.
3.3.3
network termination point
the physical point at the boundary of a network intended to accept the connection of a terminal
equipment or to be interconnected to another network
3.3.4
paired conductor interface
a port for connection of a cable providing for symmetrical transmission (for example, twisted
pair) to equipment
NOTE In this technical report the use of both indoor and outdoor twisted pair cables is considered separately.
3.3.5
terminal connection point
the physical point of the terminal equipment intended to be connected to a network

– 10 – TR 62102  IEC:2005(E)
3.4 Abbreviations
For the purposes of this technical report, the following abbreviations apply to Clause 4,
Annex B and Annex C:
ADSL Asymmetric Digital Subscriber Line
DLL Digital Local Line
DSL Digital Subscriber Line
ESD Electrostatic Discharge
HPNA Home Phone-Line Networking Architecture
ISDN Integrated Services Digital Network
KYBD Keyboard
LAN Local Area Network
LEPM Primary Multiplex
LPZ Lightning Protection Zone
LTU Line termination unit
NCP Network Connection Point
NO Network Operator
NT Network Termination
NTBA Network Termination, Basic Access
NTP Network Termination Point
NTU Network Terminating Unit
PABX Private Automatic Branch Exchange
PC Personal Computer
PCM Pulse Code Modulation
PNO Public Network Operator
POTS Plain Old Telephone Service
PSTN Public Switched Telephone Network
RFT Remote Feeding Telecommunication
RPS Remote Power Supply
RS Recommended Standard
SDH Synchronous Digital Hierarchy
TA Terminal Adapter
TCP Terminal Connection Point
TE Terminal Equipment
USB Universal Serial Bus
VGA Video Graphics Array
ZWRBA Regenerator, Basic Access
4 Reference configuration
Figure 1 illustrates a hypothetical configuration of "network clouds" giving examples of the
types of equipments covered by this technical report. Certain of these equipments will only
have one or two interface types, others may have many. Certain of the "network clouds" will be
elements within the PSTN (where the possibility of more than one network operator exists) and
others may be private networks. The equipment connected to this "network cloud" and part of
the "network cloud" itself can be any type covered by the scope of this technical report.

TR 62102  IEC:2005(E) – 11 –
This technical report provides a framework for safety requirements and protection levels by
reference to the particular examples given in Figures 1 and 2. Configurations not covered
should be treated using the same principles.
e.g. Analogue
e.g. Facsimile
PNO
telephones
machines
NO
e.g. Digital
e.g. Network
telephones
transmission
e.g. PABX
equipment &
multiplexers
PNO
NO
e.g. Modems
e.g. Network & switching
e.g. Terminal
equipment
e.g. Telephone
answering
machines
IEC  741/05
Figure 1 – Reference configuration
Where, in a practical situation, an equipment has two or more interfaces of different types, it is
normally ne
...