IEC 60364-5-54:2011

IEC 60364-5-54 ®
Edition 3.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ

Low-voltage electrical installations –
Part 5-54: Selection and erection of electrical equipment – Earthing
arrangements and protective conductors

Installations électriques basse-tension –
Partie 5-54: Choix et mise en œuvre des matériels électriques – Installations de
mise à la terre et conducteurs de protection

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IEC 60364-5-54 ®
Edition 3.0 2011-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ

Low-voltage electrical installations –
Part 5-54: Selection and erection of electrical equipment – Earthing
arrangements and protective conductors

Installations électriques basse-tension –
Partie 5-54: Choix et mise en œuvre des matériels électriques – Installations de
mise à la terre et conducteurs de protection

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 29.020; 91.140.50 ISBN 978-2-88912-400-8

– 2 – 60364-5-54  IEC:2011
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
541 General . 7
541.1 Scope . 7
541.2 Normative references . 7
541.3 Terms and definitions . 8
542 Earthing arrangements . 9
542.1 General requirements . 9
542.2 Earth electrodes . 10
542.3 Earthing conductors . 12
542.4 Main earthing terminal . 13
543 Protective conductors . 13
543.1 Minimum cross-sectional areas . 13
543.2 Types of protective conductors . 15
543.3 Electrical continuity of protective conductors . 16
543.4 PEN, PEL or PEM conductors . 16
543.5 Combined protective and functional earthing conductors . 18
543.6 Currents in protective earthing conductors . 19
543.7 Reinforced protective earthing conductors for protective earthing
conductor currents exceeding 10mA . 19
543.8 Arrangement of protective conductors . 19
544 Protective bonding conductors . 19
544.1 Protective bonding conductors for connection to the main earthing
terminal . 19
544.2 Protective bonding conductors for supplementary bonding . 20
Annex A (normative) Method for deriving the factor k in 543.1.2 (see also IEC 60724
and IEC 60949) . 21
Annex B (informative) Example of earthing arrangements and protective conductors . 25
Annex C (informative) Erection of concrete-embedded foundation earth electrodes . 27
Annex D (informative) Erection of soil-embedded earth electrodes . 30
Annex E (informative) List of notes concerning certain countries . 34
Bibliography . 40

Figure 54.1 – Examples of a PEN conductor connection . 18
Figure B.54.1 – Examples of earthing arrangements for foundation earth electrode,
protective conductors and protective bonding conductors . 26

Table 54.1 – Minimum size of commonly used earth electrodes, embedded in soil or
concrete used to prevent corrosion and provide mechanical strength . 11
Table 54.2 – Minimum cross-sectional area of protective conductors (where not

calculated in accordance with 543.1.2) . 14
Table A.54.1 – Value of parameters for different materials . 21
Table A.54.2 – Values of k for insulated protective conductors not incorporated in
cables and not bunched with other cables . 22
Table A.54.3 – Values of k for bare protective conductors in contact with cable
covering but not bunched with other cables . 22

60364-5-54  IEC:2011 – 3 –
Table A.54.4 – Values of k for protective conductors as a core incorporated in a cable
or bunched with other cables or insulated conductors . 23
Table A.54.5 – Values of k for protective conductors as a metallic layer of a cable, e.g.
armour, metallic sheath, concentric conductor, etc. . 24
Table A.54.6 – Values of k for bare conductors where there is no risk of damage to any
neighbouring material by the temperature indicated . 24
Table D.54.1 – Resistivity for types of soil . 31
Table D.54.2 – Variation of the resistivity for different types of soil . 31

– 4 – 60364-5-54  IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –

Part 5-54: Selection and erection of electrical equipment –
Earthing arrangements and protective conductors

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
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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.
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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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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
International Standard IEC 60364-5-54 has been prepared by IEC technical committee
64: Electrical installations and protection against electric shock.
This third edition cancels and replaces the second edition, published in 2002, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
– clarification of the definition of protective conductor;
– improved specification of mechanical characteristics of the earth electrode;
– introduction of earth electrode for protection against electric shock and lighting protection;
– annexes describing concrete-embedded foundation earth electrodes and soil-embedded
earth electrode.
The text of this standard is based on the following documents:

60364-5-54  IEC:2011 – 5 –
FDIS Report on voting
64/1755/FDIS 64/1766/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
It has the status of a basic safety publication in accordance with IEC Guide 104.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The reader's attention is drawn to the fact that Annex E lists all of the "in-some-country"
clauses on differing practices of a less permanent nature relating to the subject of this
standard.
A list of all parts in the IEC 60364 series, under the general title: Low-voltage electrical
installations, can be found on the IEC website.
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.
– 6 – 60364-5-54  IEC:2011
INTRODUCTION
Clause numbering is sequential, preceded by the number of this Part. Numbering of figures
and tables takes the number of this part followed by a sequential number, i.e. Table 54.1,
54.2, etc. Numbering of figures and tables in annexes takes the letter of the annex, followed
by the number of the part, followed by a sequential number, e.g. A.54.1, A.54.2, etc.

60364-5-54  IEC:2011 – 7 –
LOW-VOLTAGE ELECTRICAL INSTALLATIONS –

Part 5-54: Selection and erection of electrical equipment –
Earthing arrangements and protective conductors

541 General
541.1 Scope
This part of IEC 60364 addresses the earthing arrangements and protective conductors
including protective bonding conductors in order to satisfy the safety of the electrical
installation.
541.2 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 60364-4-41:2005, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-4-44:2007, Low-voltage electrical installations – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-5-51:2005, Electrical installations of buildings – Part 5-51: Selection and erection
of electrical equipment – Common rules
IEC 60439-2, Low-voltage switchgear and controlgear assemblies – Part 2: Particular
requirements for busbar trunking systems (busways)
IEC 61439-1, Low-voltage switchgear and controlgear assemblies – Part 1: General rules
IEC 61439-2, Low-voltage switchgear and controlgear assemblies – Part 2: Power switchgear
and controlgear assemblies
IEC 60724, Short-circuit temperature limits of electric cables with rated voltages of 1 kV (U =
m
1,2 kV) and 3 kV (U = 3,6 kV)
m
IEC 60909-0, Short-circuit currents in three-phase a.c. systems – Part 0: Calculation of
currents
IEC 60949, Calculation of thermally permissible short-circuit currents, taking into account
non-adiabatic heating effects
IEC 61140:2001, Protection against electric shock – Common aspects for installation and
equipment
IEC 61534-1, Powertrack systems – Part 1: General requirements
IEC 62305 (all parts) Protection against lightning
IEC 62305-3:2006, Protection against lightning – Part 3: Physical damage to structures and
life hazard
– 8 – 60364-5-54  IEC:2011
541.3 Terms and definitions
For the purposes of this document, the terms and definitions of IEC 61140, together with the
following definitions, apply.
Definitions used for earthing arrangements, protective conductors and protective bonding
conductors are illustrated in Annex B and listed below:
541.3.1
exposed-conductive-part
conductive part of equipment which can be touched and which is not normally live, but which
can become live when basic insulation fails
[IEC 60050-826:2004, 826-12-10]
541.3.2
extraneous-conductive-part
conductive part not forming part of the electrical installation and liable to introduce an electric
potential, generally the electric potential of a local earth
[IEC 60050-825:2004, IEV 826-12-11]
541.3.3
earth electrode
conductive part, which may be embedded in the soil or in a specific conductive medium, e.g.
concrete, in electrical contact with Earth
[IEC 60050-826:2004, 826-13-05, modified]
541.3.4
concrete-embedded foundation earth electrode
earth electrode embedded in concrete of a building foundation, generally in the form of a
closed loop
[IEC 60050-826:2004, 826-13-08, modified]
541.3.5
soil-embedded foundation earth electrode
earth electrode buried in the soil under a building foundation, generally in the form of a closed
loop
[IEC 60050-826:2004, 826-13-08, modified]
541.3.6
protective conductor
conductor provided for purposes of safety, for example protection against electric shock
[IEC 60050-826:2004, 826-13-22]
NOTE Examples of a protective conductor include a protective bonding conductor, a protective earthing conductor
and an earthing conductor when used for protection against electric shock.

60364-5-54  IEC:2011 – 9 –
541.3.7
protective bonding conductor
protective conductor provided for protective-equipotential-bonding
[IEC 60050-826:2004, 826-13-24]
541.3.8
earthing conductor
conductor which provides a conductive path, or part of the conductive path, between a given
point in a system or in an installation or in equipment and an earth-electrode network
[IEC 60050-826:2004, 826-13-12]
NOTE For the purposes of this part of IEC 60364, an earthing conductor is the conductor which connects the
earth electrode to a point in the equipotential bonding system, usually the main earthing terminal.
541.3.9
main earthing terminal
main earthing busbar
terminal or busbar which is part of the earthing arrangement of an installation and enabling
the electrical connection of a number of conductors for earthing purposes
[IEC 60050-826:2004, 826-13-15]
541.3.10
protective earthing conductor
protective conductor provided for protective earthing
[IEC 60050-826:2004, 826-13-23]
541.3.11
functional earthing
earthing a point or points in a system or in an installation or in equipment, for purposes other
than electrical safety
[IEC 60050-826:2004, IEV 826-13-10]
541.3.12
earthing arrangement
all the electrical connections and devices involved in the earthing of a system, installation or
an equipment
[IEC 60050-195:2004, 195-02-20]
542 Earthing arrangements
542.1 General requirements
542.1.1 The earthing arrangements may be used jointly or separately for protective and
functional purposes according to the requirements of the electrical installation. The
requirements for protective purposes shall always take precedence.
542.1.2 Where provided, earth electrodes within an installation shall be connected to the
main earthing terminal using an earthing conductor.
NOTE An installation does not need to have its own earth electrode.

– 10 – 60364-5-54  IEC:2011
542.1.3 Where the supply to an installation is at high voltage, requirements concerning the
earthing arrangements of the high voltage supply and of the low-voltage installation shall also
comply with Clause 442 of IEC 60364-4-44:2007.
542.1.4 The requirements for earthing arrangements are intended to provide a connection to
earth which:
– is reliable and suitable for the protective requirements of the installation;
– can carry earth fault currents and protective conductor currents to earth without danger
from thermal, thermo-mechanical and electromechanical stresses and from electric shock
arising from these currents;
– if relevant, is also suitable for functional requirements;
– is suitable for the foreseeable external influences (see IEC 60364-5-51), e.g. mechanical
stresses and corrosion.
542.1.5 Consideration shall be given to the earthing arrangements where currents with high
frequencies are expected to flow (see Clause 444 of IEC 60364-4-44:2007).
542.1.6 Protection against electric shock, as stated in IEC 60364-4-41, shall not be
adversely affected by any foreseeable change of the earth electrode resistance (e.g. due to
corrosion, drying or freezing).
542.2 Earth electrodes
542.2.1 The type, materials and dimensions of earth electrodes shall be selected to
withstand corrosion and to have adequate mechanical strength for the intended lifetime.
NOTE 1 For corrosion, the following parameters may be considered: the soil pH at the site, soil resistivity, soil
moisture, stray and leakage a.c. and d.c. current, chemical contamination, and proximity of dissimilar materials.
For materials commonly used for earth electrodes, the minimum sizes, from the point of view
of corrosion and mechanical strength, when embedded in the soil or in concrete, shall be as
specified in Table 54.1.
NOTE 2 The minimum thickness of protective coating is greater for vertical earth electrodes than for horizontal
earth electrodes because of their greater exposure to mechanical stresses while being embedded.
If a lightning protection system is required, 5.4 of IEC 62305-3:2006 applies.

60364-5-54  IEC:2011 – 11 –
Table 54.1 – Minimum size of commonly used earth electrodes, embedded in soil or
concrete used to prevent corrosion and provide mechanical strength
Cross- Thickness
Weight of
Diameter sectional Thickness of coating/
coating
Material and surface Shape
area sheathing
2 2
mm mm mm g/m µm
Steel embedded in Round wire 10
concrete (bare, hot
Solid tape or strip 75 3
galvanized or stainless)
b
Strip or shaped strip/plate
90 3 500 63
– Solid plate – Lattice plate
Round rod installed
16  350 45
vertically
Round wire installed
10  350 45
c horizontally
Steel hot-dip galvanized
Pipe 25 2 350 45
Stranded
(embedded in concrete)
Cross profile installed
(290) 3
vertically
Round rod installed
Steel copper-sheathed (15)  2 000
vertically
Round rod installed e
14  250
vertically
Steel with electro-
Round wire installed
deposited copper coating (8)  70
horizontally
Strip installed horizontally 90 3 70

b
Strip or shaped strip/plate 90 3
Round rod installed
vertically
a
Stainless steel
Round wire installed
horizontally
Pipe 25 2
Strip 50 2
Round wire installed
d
(25) 50
horizontally
Solid round rod installed
(12) 15
vertically
1,7 for
Copper
individual
d
Stranded wire
(25) 50
strands of
wire
Pipe 20 2
Solid plate  (1,5) 2
Lattice plate  2
NOTE Values in brackets are applicable for protection against electric shock only, while values not in brackets are

applicable for lightning protection and for protection against electric shock.
a
Chromium ≥16 %, Nickel ≥5 %, Molybdenum ≥2 %, Carbon ≤0,08 %.
b
As rolled strip or slit strip with rounded edges.
c
The coating shall be smooth, continuous and free from flux stains.
d
Where experience shows that the risk of corrosion and mechanical damage is extremely low, 16 mm² can be used.
e
This thickness is provided to withstand mechanical damage of copper coating during the installation process. It may

– 12 – 60364-5-54  IEC:2011
be reduced to not less than 100 µm where special precautions to avoid mechanical damage of copper during the
installation process (e.g. drilled holes or special protective tips) are taken according to the manufacturer’s
instructions.
542.2.2 The efficacy of any earth electrode depends on its configuration and upon local soil
conditions. One or more earth electrodes suitable for the soil conditions and the value of
resistance to earth required shall be selected.
Annex D gives methods of estimation of earth electrode resistance.
542.2.3 The following are examples of earth electrodes which may be used:
– concrete-embedded foundation earth electrode;
NOTE For more information see Annex C.
– soil-embedded foundation earth electrode;
– metallic electrode embedded directly in soil vertically or horizontally (e.g. rods, wires,
tapes, pipes or plates);
– metal sheath and other metal coverings of cables according to local conditions or
requirements;
– other suitable underground metalwork (e.g. pipes) according to local conditions or
requirements;
– welded metal reinforcement of concrete (except pre-stressed concrete) embedded in the
earth.
542.2.4 When selecting the type and embedded depth of an earth electrode, consideration
shall be given to possible mechanical damage and to local conditions to minimize the effect of
soil drying and freezing.
542.2.5 Consideration shall be given to electrolytic corrosion when using different materials
in an earthing arrangement. For external conductors (e.g. earthing conductor) connected to a
concrete-embedded foundation earth electrode, the connection made from hot-dip galvanized
steel shall not be embedded in the soil.
542.2.6 The earthing arrangement shall not rely on a metallic pipe for flammable liquids or
gases as the earth electrode and their buried length shall not be considered when
dimensioning the earth electrode.
NOTE This requirement does not preclude the protective equipotential bonding via the main earthing terminal
(541.3.9) of such pipes for compliance with IEC 60364-4-41.
Where cathodic protection is applied and the exposed-conductive-part of an item of electrical
equipment supplied by a TT system is directly connected to the pipe, a metallic pipe for
flammable liquids or gases may act as the sole earth electrode for this specific equipment.
542.2.7 Earth electrodes shall not be directly immersed in water of a stream, river, pond,
lake or the like (see also 542.1.6).
542.2.8 Where an earth electrode consists of parts that must be connected together, the
connection shall be by exothermic welding, pressure connectors, clamps or other suitable
mechanical connectors.
NOTE Connections made by a wrapped iron wire only are not suitable for protection purposes.
542.3 Earthing conductors
542.3.1 Earthing conductors shall comply with 543.1.1 or 543.1.2. Their cross-sectional area
2 2
shall be not less than 6 mm for copper or 50 mm for steel. Where a bare earthing conductor

60364-5-54  IEC:2011 – 13 –
is buried in the soil, its dimensions and characteristics shall also be in accordance with Table
54.1.
Where no noticeable fault current is expected to flow through the earth electrode (e.g. in TN
systems or IT systems), the earthing conductor may be dimensioned according to 544.1.
Aluminium conductors shall not be used as earthing conductors.
NOTE Where a lightning protection system is connected to the earth electrode, the cross-sectional area of the
earthing conductor should be at least 16 mm² for copper (Cu) or 50 mm² for iron (Fe) (see the IEC 62305 series).
542.3.2 The connection of an earthing conductor to an earth electrode shall be soundly
made and electrically satisfactory. The connection shall be by exothermic welding, pressure
connectors, clamps or other suitable mechanical connectors. Mechanical connectors shall be
installed in accordance with the manufacturer’s instructions. Where a clamp is used, it shall
not damage the electrode or the earthing conductor.
Connection devices or fittings that depend solely on solder shall not be used independently,
as they do not reliably provide adequate mechanical strength.
NOTE Where vertical electrodes are installed, means may be provided to allow the inspection of the connection
and the replacement of the vertical rod.
542.4 Main earthing terminal
542.4.1 In every installation where protective equipotential bonding is used, a main earthing
terminal shall be provided and the following shall be connected to it:
– protective bonding conductors;
– earthing conductors;
– protective conductors;
– functional earthing conductors, if relevant.
NOTE 1 It is not intended to connect every individual protective conductor directly to the main earthing terminal
where they are connected to this terminal by other protective conductors.
NOTE 2 The main earthing terminal of the building can generally be used for functional earthing purposes. For
information technology purposes, it is then regarded as the connection point to the earth.
Where more than one earthing terminal is provided, they shall be interconnected.
542.4.2 Each conductor connected to the main earthing terminal shall be able to be
disconnected individually. This connection shall be reliable and such that it can only be
disconnected by means of a tool.
NOTE Disconnection means may conveniently be combined with the main earthing terminal, to permit
measurement of the resistance of the earth electrode.
543 Protective conductors
NOTE Consideration should be given to requirements provided in Clause 516 of IEC 60364-5-51:2005.
543.1 Minimum cross-sectional areas
543.1.1 The cross-sectional area of every protective conductor shall satisfy the conditions
for automatic disconnection of supply required in 411.3.2 of IEC 60364-4-41:2005 and be
capable of withstanding mechanical and thermal stresses caused by the prospective fault
current during the disconnection time of the protective device.

– 14 – 60364-5-54  IEC:2011
The cross-sectional area of a protective conductor shall either be calculated in accordance
with 543.1.2, or selected in accordance with Table 54.2. In either case, the requirements of
543.1.3 shall be taken into account.
Terminals for protective conductors shall be capable of accepting conductors of dimensions
required by this subclause.
In TT systems, where the earth electrodes of the supply system and of the exposed-
conductive- parts are electrically independent (see 312.2.2), the cross-sectional area of
protective conductors need not exceed:
– 25 mm copper,
– 35 mm aluminium.
Table 54.2 – Minimum cross-sectional area of protective conductors
(where not calculated in accordance with 543.1.2)
Minimum cross-sectional area of the corresponding protective
conductor
Cross-sectional area
mm Cu
of line conductor, S
If the protective conductor is of the If the protective conductor is not
mm Cu
same material as the line of the same material as the line
conductor conductor
k
× S
S ≤16 S
k
k
a
×16
16 < S ≤35 16
k
k S
S
a
×
S >35
k 2
where
k is the value of k for the line conductor derived from the formula in Annex A or selected from tables in IEC 60364-
4-43, according to the materials of the conductor and insulation;
k is the value of k for the protective conductor, selected from Tables A.54.2 to A.54.6 as applicable.
a
For a PEN conductor, the reduction of the cross-sectional area is permitted only in accordance with the rules for
sizing of the neutral conductor (see IEC 60364-5-52).

543.1.2 The cross-sectional areas of protective conductors shall be not less than the value
determined either:
– in accordance with IEC 60949; or
– by the following formula applicable only for disconnection times not exceeding 5 s:
I t
S =
k
where
S is the cross-sectional area in mm ;
I is the r.m.s value expressed in amperes of prospective fault current, for a fault of
negligible impedance, which can flow through the protective device (see IEC 60909-0);
t is the operating time in seconds of the protective device for automatic disconnection;
k is the factor dependent on the material of the protective conductor, the insulation and
other parts and the initial and final temperatures (for calculation of k, see Annex A).

60364-5-54  IEC:2011 – 15 –
Where the application of the formula produces a non-standard size, a conductor having at
least the nearest larger standard cross-sectional area shall be used.
NOTE 1 Account should be taken of the current-limiting effect of the circuit impedances and the limitation of I²t of
the protective device.
NOTE 2 For limitations of temperatures for installations in potentially explosive atmospheres, see IEC 60079-0.
NOTE 3 As the metallic sheaths of mineral-insulated cables according to IEC 60702-1 have an earth fault
capacity greater than that of the line conductors, it is not necessary to calculate the cross-sectional area of the
metallic sheaths when used as protective conductors.
543.1.3 The cross-sectional area of every protective conductor which does not form part of a
cable or which is not in a common enclosure with the line conductor shall be not less than
2 2
– 2,5 mm Cu or 16 mm Al if protection against mechanical damage is provided,
2 2
– 4 mm Cu or 16 mm Al if protection against mechanical damage is not provided.
NOTE The use of steel for a protective conductor is not excluded (see 543.1.2).
A protective conductor not forming part of a cable is considered to be mechanically protected
if it is installed in a conduit, trunking or protected in a similar way.
543.1.4 Where a protective conductor is common to two or more circuits, its cross-sectional
area shall be:
– calculated in accordance with 543.1.2 for the most onerous prospective fault current and
operating time encountered in these circuits; or
– selected in accordance with Table 54.2 so as to correspond to the cross-sectional area of
the largest line conductor of the circuits.
543.2 Types of protective conductors
543.2.1 Protective conductors may consist of one or more of the following:
– conductors in multicore cables;
– insulated or bare conductors in a common enclosure with live conductors;
– fixed installed bare or insulated conductors;
– metallic cable sheath, cable screen, cable armour, wirebraid, concentric conductor,
metallic conduit, subject to the conditions stated in 543.2.2. a) and b).
NOTE See 543.8 for their arrangement.
543.2.2 Where the installation contains equipment having metal enclosures such as low-
voltage switchgear and controlgear assemblies (see IEC 61439-1 and IEC 61439-2) or busbar
trunking systems (see IEC 60439-2), their metal enclosures or frames may be used as
protective conductors if they simultaneously satisfy the following three requirements:
a) their electrical continuity shall be assured by construction or by suitable connection so as
to ensure protection against mechanical, chemical or electrochemical deterioration;
b) they comply with the requirements of 543.1;
c) they shall permit the connection of other protective conductors at every predetermined
tap-off point.
543.2.3 The following metal parts are not permitted for use as protective conductors or as
protective bonding conductors:
– metallic water pipes;
– metallic pipes containing potentially flammable materials such as gases, liquids, powder;
NOTE 1 For cathodic protection, see 542.2.6.

– 16 – 60364-5-54  IEC:2011
– constructional parts subject to mechanical stress in normal service;
– flexible or pliable metal conduits, unless designed for that purpose;
– flexible metal parts;
– support wires; cable trays and cable ladders.
NOTE 2 Examples of a protective conductor include a protective bonding conductor, a protective earthing
conductor and an earthing conductor when used for protection against electric shock.
543.3 Electrical continuity of protective conductors
543.3.1 Protective conductors shall be suitably protected against mechanical damage,
chemical or electrochemical deterioration, electrodynamic forces and thermodynamic forces.
Every connection (e.g. screwed connections, clamp connectors) between protective
conductors or between a protective conductor and other equipment shall provide durable
electrical continuity and adequate mechanical strength and protection. Screws for connecting
protective conductors shall not serve any other purpose.
Joints shall not be made by soldering.
NOTE All electrical connections should have satisfactory thermal capacity and mechanical strength to withstand
any combination of current/time which may occur in the conductor or in the cable/enclosure with the largest cross-
sectional area.
543.3.2 Joints in protective conductors shall be accessible for inspection and testing except
for
– compound-filled joints,
– encapsulated joints,
– joints in metal conduits, ducting and busbar trunking systems,
– joints forming part of equipment, complying with equipment standards,
– joints made by welding or brazing,
– joints made by compression tool.
543.3.3 No switching device shall be inserted in the protective conductor, but joints which
can be disconnected for test purposes by use of a tool may be provided.
543.3.4 Where electrical monitoring of earthing is used, dedicated devices (e.g. operating
sensors, coils, current transformers) shall not be connected in series in protective conductors.
543.3.5 Exposed-conductive-parts of electrical equipment shall not be used to form part of
the protective conductor for other equipment except as allowed by 543.2.2.
543.4 PEN, PEL or PEM conductors
NOTE As these conductors serve two functions, as PE- and either as N-, L- or M-conductors, all applicable
requirements for the relevant functions should be considered.
543.4.1 A PEN, PEL or PEM conductor may only be used in fixed electrical installations and,
for mechanical reasons, shall have a cross-sectional area not less than 10 mm copper or 16
mm² aluminium.
NOTE 1 For EMC reasons, the PEN conductor should not be installed downstream of the origin of the installation
(see 444.4.3.2 of IEC 60364-4-44:2007).
NOTE 2 IEC 60079-14 does not permit the use of a PEN, PEL or PEM conductor in explosive atmospheres.

60364-5-54  IEC:2011 – 17 –
543.4.2 The PEN, PEL or PEM conductor shall be insulated for the rated voltage of the line
conductor.
Metallic enclosures of wiring systems shall not be used as PEN, PEL or PEM conductors,
except for busbar trunking systems complying with IEC 60439-2 and for powertrack systems
complying with IEC 61534-1.
NOTE Product committees should consider the potential effect of EMI introduced into the equipment from a PEN,
PEL or PEM conductor.
543.4.3 If, from any point of the installation, the neutral/mid-point/line and protective
functions are provided by separate conductors, it is not permitted to connect the neutral/mid-
point/line conductor to any other earthed part of the installation. However, it is permitted to
form more than one neutral/mid-point/line conductor and more than one protective conductor
from the PEN, PEL or PEM conductor respectively.
The PEN, PEL or PEM conductor shall be connected to the terminal or bar intended for the
protective conductors (see Figure 54.1a), unless there is a specific terminal or bar intended
for the connection of the PEN, PEL or PEM conductor (examples are given in Figures 54.1b
and 54.1c).
IEC  523/11
Figure 54.1a – Example 1
– 18 – 60364-5-54  IEC:2011
IEC  524/11
Figure 54.1b – Example 2
IEC  525/11
Figure 54.1c – Example 3
Key
MDB main distribution board
Figure 54.1 – Examples of a PEN conductor connection
NOTE In systems supplied with SELV direct current, e.g. telecommunication systems, there is no PEL or PEM
conductor.
543.4.4 Extraneous-conductive-parts shall not be used as PEN, PEL or PEM conductors.
543.5 Combined protective and functional earthing conductors
Where a combined protective and functional earthing conductor is used, it shall satisfy the
requirements for a protective conductor. In addition, it shall also comply with the relevant
functional requirements (see Clause 444 of IEC 60364-4-44:2007).

60364-5-54  IEC:2011 – 19 –
A d.c. return conductor PEL or PEM for an information technology power supply may also
serve as a combined functional earthing and protective conductor.
NOTE For further information, see 7.5.3.1 of IEC 61140:2001.
543.6 Currents in prote
...