SIST EN 300 253 V2.1.1:2006

SLOVENSKI STANDARD
01-februar-2006
Okoljski inženiring (EE) – Konfiguracija ozemljitev in povezav v
telekomunikacijskih centrih
Environmental Engineering (EE); Earthing and bonding of telecommunication equipment
in telecommunication centres
Ta slovenski standard je istoveten z: EN 300 253 Version 2.1.1
ICS:
19.040 Preskušanje v zvezi z Environmental testing
okoljem
33.050.01 Telekomunikacijska Telecommunication terminal
terminalska oprema na equipment in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

European Standard (Telecommunications series)
Environmental Engineering (EE);
Earthing and bonding configuration
inside telecommunications centres

2 ETSI EN 300 253 V2.1.1 (2002-04)
Reference
REN/EE-02009
Keywords
bonding, earthing, equipment practice
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3 ETSI EN 300 253 V2.1.1 (2002-04)
Contents
Intellectual Property Rights.4
Foreword.4
Introduction .5
1 Scope .6
2 References .6
3 Definitions and abbreviations.7
3.1 Definitions.7
3.1.1 IEC definitions (by IEC 60050 numbers) .7
3.1.2 Telecommunication definitions .8
3.2 Abbreviations .9
4 General requirements .9
4.1 Safety from electrical hazards .9
4.2 Signal reference.9
4.3 EMC performance .9
5 Requirements on bonding networks.10
5.1 Bonding configurations .10
5.2 CBN within a telecommunication building .10
5.3 BN within a telecommunication system.10
5.4 Merging of CBN and MESH-BNs .13
5.5 Cabling within and between BNs .13
6 Requirements for power distribution.13
6.1 DC power distribution of secondary supply.13
6.2 DC power distribution of tertiary supplies .13
6.3 AC mains distribution and bonding of the protective conductor.14
6.4 AC power distribution from tertiary power supply .14
Annex A (normative): Rationale about CBN co-ordination.17
Annex B (informative): Rationale about the integration of the DC return conductor into the
merged CBN/MESH-BN .18
Annex C (informative): Bibliography.20
History .21
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4 ETSI EN 300 253 V2.1.1 (2002-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Environmental
Engineering (EE).
The present document has been produced within the framework of the following considerations:
a) centralized telecommunication equipment is generally installed in telecommunication centres and held in racks,
cabinets or other mechanical structures;
b) the existing ITU-T and CCIR Recommendations and CENELEC standards in such matters do not ensure the
required standardization at the equipment level;
c) network operators and equipment providers agreed to standardize on a bonding configuration that facilitates:
- compliance with functional requirements including Electromagnetic Compatibility (EMC) aspects of
emission and immunity;
- compatible building and equipment provisions;
- installation of new telecommunication centres as well as expansion or replacement of installations in existing
telecommunication centres with equipment coming from different suppliers;
- a structured installation practice;
- simple maintenance rules;
- contractingona commonbasis;
- cost effectiveness in development, manufacturing, installation and operation.
National transposition dates
Date of adoption of this EN: 26 April 2002
Date of latest announcement of this EN (doa): 31 July 2002
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 January 2003
Date of withdrawal of any conflicting National Standard (dow): 31 January 2003
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5 ETSI EN 300 253 V2.1.1 (2002-04)
Introduction
The present document addresses earthing and bonding of telecommunication equipment in telecommunication centres
in relation to safety, functional performance and EMC.
Information regarding the general principles on earthing for telecommunication sites has been published by the ITU-T
in the handbook on "Earthing of telecommunication installations" (see bibliography). ITU-T Recommendation K.27
deals with bonding configurations and earthing inside a telecommunication building. One bonding configuration only is
selected from ITU-T Recommendation K.27 (CBN/MESH-BN) and tailored to the present document.
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6 ETSI EN 300 253 V2.1.1 (2002-04)
1 Scope
The present document applies in telecommunication centres and similar installations to the bonding network of the
building, the bonding network of the equipment, and the interconnection between these two networks. It contributes to
the standardization of telecommunication and datacom equipment installation.
It also co-ordinates with the pre-conditions of the installation to achieve the following targets:
- safety from electrical hazards;
- reliable signal reference;
- satisfactory Electromagnetic Compatibility (EMC) performance.
A defined bonding configuration down to the equipment level shall facilitate the installation, operation and maintenance
of telecommunication centres in telecommunication buildings or similar installations independent of the equipment
supplier.
The specification of telecommunication and datacom equipment and of the pre-conditions of installation are subject to
agreement of the parties (e.g. the supplier and the purchaser). Annex A can be used in the procedure to achieve
agreement.
The present document does not cover safety and EMC aspects of the equipment. Those aspects are covered by other
relevant standards.
The present document does not apply to the installation of telecommunication and datacom equipment in locations other
than telecommunication centres, e.g.:
- smaller telecommunication equipment inside a subscriber's building;
- subscriber line terminal equipment.
NOTE: Earthing and bonding of equipment installed in locations other than telecommunication building is
covered by EN 50310 [8].
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
• References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies.
[1] CENELEC HD 384.4.41: "Electrical installation of buildings - Part 4: Protection for safety -
Chapter 41: Protection against electric shock".
[2] CENELEC HD 384.5.54: "Electrical installation of buildings - Part 5: Selection and erection of
electrical equipment - Chapter 54: Earthing arrangements and protective conductors".
[3] EN 60950: "Safety of information technology equipment".
[4] EN 41003: "Particular safety requirements for equipment to be connected to telecommunication
networks".
[5] IEC 60050: "International Electrotechnical Vocabulary".
[6] IEC 60050-604: "International Electrotechnical Vocabulary. Chapter 604: Generation,
transmission and distribution of electricity - Operation".
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7 ETSI EN 300 253 V2.1.1 (2002-04)
[7] IEC 60050-826: "International Electrotechnical Vocabulary. Electrical installations of buildings".
[8] EN 50310: "Application of equipotential bonding and earthing in buildings with information
technology equipment".
[9] IEC 61024-1: "Protection of structures against lightning - Part 1: General principles".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply.
The following definitions with respect to earthing and bonding are introduced by the IEC 60050 [5] and are used within
the present document to maintain conformity.
3.1.1 IEC definitions (by IEC 60050 numbers)
NOTE: IEC 60050 [5] references are given in parentheses (see IEC 60050-604 [6] and IEC 60050-826 [7]).
earth (826-04-01): conductive mass of earth, whose electric potential at any point is conventionally taken as equal to
zero
earthing conductor (826-04-07): protective conductor connecting the main earthing terminal or bar to the earth
electrode
earth electrode (826-04-02): conductive part or a group of conductive parts in intimate contact with and providing an
electrical connection with earth
earthing network (604-04-07): part of an earthing installation that is restricted to the earth electrodes and their
interconnections
equipotential bonding (826-04-09): electrical connection putting various exposed conductive parts and extraneous
conductive parts at a substantially equal potential
equipotential bonding conductor (826-04-10): protective conductor for ensuring equipotential bonding
IT: See IEC 60364-3.
main earthing terminal (826-04-08): terminal or bar provided for the connection of protective conductors, including
equipotential bonding conductors and conductors for functional earthing if any, to the means of earthing
Neutral conductor (N) (826-01-03): conductor connected to the neutral point of a system and capable of contributing
to the transmission of electrical energy
PEN conductor (826-04-06): earthed conductor combining the functions of both protective conductor and neutral
conductor
Protective conductor (PE) (826-04-05): conductor required by some measures for protection against electric shock by
electrically connecting any of the following parts:
- exposed conductive parts;
- extraneous conductive parts;
- main earthing terminal;
- earth electrode;
- earthed point of the source or artificial neutral.
TN-C: See IEC 60364-3.
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8 ETSI EN 300 253 V2.1.1 (2002-04)
TN-S: See IEC 60364-3.
TT: See IEC 60364-3.
3.1.2 Telecommunication definitions
The following definitions, specific to telecommunication installations and not covered by the IEC 60050 [5], are used
within the present document. Correspondence to ITU-T Recommendation K.27 (see bibliography) is indicated as
appropriate.
bonding mat: essential means to provide a SRPP by a discernible, nearly regular mesh structure
NOTE: The bonding mat may be located either below or above a collection of equipment constituting a system
block.
Bonding Network (BN), (ITU-T Recommendation K.27): set of interconnected conductive structures that provides an
"electromagnetic shield" for electronic systems and personnel at frequencies from Direct Current (DC) to low Radio
Frequency (RF)
NOTE: The term "electromagnetic shield" denotes any structure used to divert, block or impede the passage of
electromagnetic energy. In general, a BN need not be connected to earth but all BNs considered in the
present document will have an earth connection.
Common Bonding Network (CBN), (ITU-T Recommendation K.27): principal means for effective bonding and
earthing inside a telecommunication building
NOTE: It is the set of metallic components that are intentionally or incidentally interconnected to form the
principal BN in a building. These components include: structural steel or reinforcing rods, metallic
plumbing, Alternating Current (AC) power conduit, PE conductors, cable racks and bonding conductors.
The CBN always has a mesh topology and is connected to the earthing network.
DC return conductor: (+) conductor of the -48 V or -60 V secondary DC supply
MESHed Bonding Network (MESH-BN), (ITU-T Recommendation K.27): bonding network in which all associated
equipment frames, racks and cabinets and usually the DC power return conductor, are bonded together as well as at
multiple points to the CBN
NOTE 1: Consequently, the MESH-BN augments the CBN
NOTE 2: See figure 1 of the present document.
MESHed Isolated Bonding Network (MESH-IBN), (ITU-T Recommendation K.27): type of IBN in which the
components of the IBN (e.g. equipment frames) are interconnected to form a mesh-like structure
NOTE: This may, for example, be achieved by multiple interconnections between cabinet rows, or by connecting
all equipment frames to a metallic grid (a "bonding mat") extending beneath the equipment. The bonding
mat is, of course, insulated from the adjacent CBN. If necessary the bonding mat could include vertical
extensions, resulting in an approximation to a Faraday cage. The spacing of the grid is chosen according
to the frequency range of the electromagnetic environment.
power supply:
- primary supply: public mains or, under emergency conditions, a locally generated AC supply
- secondary supply: supply to the telecommunication equipment, racks or system block, derived from the primary
supply
- tertiary supplies: supplies to the telecommunication equipment, derived from the secondary supply
system: regularly interacting or interdependent group of items forming a unified whole
system block: functional group of equipment depending in its operation and performance on its connection to the same
system reference potential plane, inherent to a MESH-BN
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9 ETSI EN 300 253 V2.1.1 (2002-04)
System Reference Potential Plane (SRPP): conductive solid plane, as an ideal goal in potential equalizing, is
approached in practice by horizontal or vertical meshes
NOTE 1: The mesh width thereof is adapted to the frequency range to be considered. Horizontal and vertical
meshes may be interconnected to form a grid structure approximating to a Faraday cage.
NOTE 2: The SRPP facilitates signalling with reference to a common potential.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
BN Bonding Network
CBN Common Bonding Network
DC Direct Current
EMC ElectroMagnetic Compatibility
LPS Lightning Protection System
MESH-BN MESHed Bonding Network
MESH-IBN MESHed Isolated Bonding Network
N Neutral conductor
PE Protective conductor
PEN combined Protective conductor and Neutral conductor
RF Radio Frequency
SRPP System Reference Potential Plane
4 General requirements
4.1 Safety from electrical hazards
To achieve safety it is required to design equipment to the standards EN 60950 [3], EN 41003 [4] and
CENELEC HD 384.4.41 [1] and to perform the installation of PEs and equipotential bonding conductors, according to
CENELEC HD 384.5.54 [2].
The conductors involved shall provide sufficiently high current conducting capability and low impedance according to
the relevant safety standards to avoid electric shock, risk of fire, or damage to the equipment under normal or faulty
operating conditions within an equipment or the distribution network, or due to the impact of induced voltage and
current, e.g. by lightning.
4.2 Signal reference
Reliable signal reference shall be provided by a SRPP dedicated at least to a functional unit or a system block. To avoid
undue functional distortion or risk of component failure, the SRPP shall provide sufficiently low impedance up to the
highest frequency to be regarded by using a metal plane or a meshed configuration having adequate mesh dimensions,
e.g. a bonding mat. The frequency band to be covered shall include the spectral components of transients caused by
switching, short circuits and atmospheric discharges.
NOTE: Signal reference to the SRPP does not always imply signal return via the SRPP.
4.3 EMC performance
Measures to gain a satisfactory EMC performance shall be assisted by a SRPP. The SRPP shall provide sufficiently low
impedance for efficient connection of filters, cabinets and cable shields. The requirement to avoid undue emission of, or
susceptibility to electromagnetic energy under normal operating conditions may govern the properties of the SRPP
ahead of what is required in clause 4.2. The EM
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