IEC 60947-7-4:2019
(Main)Low-voltage switchgear and controlgear - Part 7-4: Ancillary equipment - PCB terminal blocks for copper conductors
Low-voltage switchgear and controlgear - Part 7-4: Ancillary equipment - PCB terminal blocks for copper conductors
IEC 60947-7-4:2019 specifies requirements for PCB terminal blocks primarily intended for industrial or similar use. Mounting and fixing on the printed circuit board is made by soldering, press-in or equivalent methods to provide electrical and mechanical connection between copper conductors and the printed circuit board. This document applies to PCB terminal blocks intended to connect copper conductors, with or without special preparation, having a cross-section between 0,08 mm2 and 300 mm2 (AWG 28-600 kcmil), intended to be used in circuits of a rated voltage not exceeding 1 000 V AC up to 1 000 Hz or 1 500 V DC. This second edition cancels and replaces the first edition published in 2013. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) additional test for PCB terminal blocks with clamping units, where contact pressure is transmitted through insulating materials;
b) tightening torques for screws now given in Table 4 of this document (previously given in Table 4 of IEC 60947-1:2007); tightening torques added for an additional type of screw;
c) new criteria for verification of contact resistance introduced;
d) clarification in the description of the temperature-rise test (current-temperature derating); corrections in the test sequence according to Figure 4.
Appareillage à basse tension - Partie 7-4: Matériels accessoires - Blocs de jonction pour cartes de circuits imprimés pour conducteurs en cuivre
L'IEC 60947-7-4:2018 spécifie les exigences concernant les blocs de jonction pour cartes de circuits imprimés destinés principalement à un usage industriel ou similaire. Le montage et la fixation sur la carte de circuits imprimés s'effectuent par brasage, insertion à force ou par des méthodes équivalentes afin d'assurer une connexion électrique et mécanique entre les conducteurs en cuivre et la carte de circuits imprimés. Le présent document s'applique aux blocs de jonction pour cartes de circuits imprimés destinés à connecter les conducteurs en cuivre, avec ou sans préparation spéciale, dont la section est comprise entre 0,08 mm2 et 300 mm2 (AWG 28-600 kcmil), destinés à être utilisés dans les circuits dont la tension assignée ne dépasse pas 1 000 V en courant alternatif jusqu'à 1 000 Hz ou 1 500 V en courant continu au maximum. Cette deuxième édition annule et remplace la première édition parue en 2013. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) essai complémentaire pour les blocs de jonction pour cartes de circuits imprimés à organes de serrage pour lesquels la pression de contact est transmise par des matériaux isolants;
b) les couples de serrage des vis sont désormais présentés dans le Tableau 4 du présent document (ils étaient précédemment donnés dans le Tableau 4 de l'IEC 60947-1:2007); les couples de serrage sont donnés pour un type supplémentaire de vis;
c) ajout de nouveaux critères pour la vérification de la résistance de contact;
d) clarification de la description de l'essai d'échauffement (taux de réduction de l'intensité en fonction de la température); corrections de la séquence d'essais conformément à la Figure 4.
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IEC 60947-7-4 ®
Edition 2.0 2019-01
REDLINE VERSION
INTERNATIONAL
STANDARD
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Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
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IEC 60947-7-4 ®
Edition 2.0 2019-01
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.20 ISBN 978-2-8322-6451-5
– 2 – IEC 60947-7-4:2019 RLV IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 9
4 Classification . 10
5 Characteristics . 10
5.1 Summary of characteristics . 10
5.2 Type of PCB terminal block . 10
5.3 Rated and limiting values . 11
5.3.1 Rated voltages . 11
5.3.2 Rated current . 11
5.3.3 Standard cross-sections . 11
5.3.4 Maximum cross-section . 12
5.3.5 Connecting capacity . 12
6 Product information . 13
6.1 Marking . 13
6.2 Additional information . 14
7 Normal service, mounting and transport conditions . 14
8 Constructional and performance requirements . 14
8.1 Constructional requirements . 14
8.1.1 Clamping units . 14
8.1.2 Mounting and installation . 15
8.1.3 Clearances and creepage distances . 15
8.1.4 Terminal identification and marking . 15
8.1.5 Resistance to abnormal heat and fire . 16
8.1.6 Maximum cross-section and connecting capacity . 16
8.2 Performance requirements . 16
8.2.1 Temperature-rise (current-temperature derating) . 16
8.2.2 Dielectric properties . 16
8.2.3 Short-time withstand current . 16
8.2.4 Contact resistance . 17
8.2.5 Ageing tests . 17
8.3 Electromagnetic compatibility (EMC) . 17
9 Tests . 17
9.1 Kinds of test . 17
9.2 General . 17
9.3 Verification of mechanical characteristics . 18
9.3.1 General . 18
9.3.2 Attachment of the PCB terminal block on its support . 18
9.3.3 Vacant . 19
9.3.4 Verification of the maximum cross-section and connecting capacity . 19
9.3.5 Verification of maximum cross-section (special test with gauges) . 19
9.4 Verification of electrical characteristics . 20
9.4.1 General . 20
9.4.2 Verification of clearances and creepage distances . 20
9.4.3 Dielectric tests . 20
9.4.4 Verification of contact resistance . 21
9.4.5 Temperature-rise test (current-temperature derating) . 23
9.4.6 Short-time withstand current test . 25
9.4.7 Ageing tests . 26
9.5 Verification of thermal characteristics. 30
9.6 Verification of EMC characteristics . 31
9.6.1 General . 31
9.6.2 Immunity . 31
9.6.3 Emission . 31
Annex A (informative) Structure of a PCB terminal block . 32
Annex B (informative) Additional information to be specified between the manufacturer
and the user . 33
B.1 Additional information available on request of the user . 33
B.2 Information for testing in addition to those mentioned above . 33
Annex C (informative) Examples of PCBs and PCB terminal blocks for high-current
application . 34
C.1 Layout of high-current PCBs (schematic diagram) . 34
C.2 High-current PCB terminal blocks . 35
Bibliography . 36
Figure 1 – Test assembly for the measurement of contact resistance and temperature-rise . 23
Figure 2 – Example of wiring structure of a multi-tier PCB terminal block . 24
Figure 3 – Test assembly for the measurement of short-time withstand current . 26
Figure 4 – Test sequence . 27
Figure 5 – Test sequence for PCB terminal blocks with contact pressure via insulating
material . 28
Figure 6 – Current cycling ageing test procedure . 30
Figure A.1 – Structure of a PCB terminal block . 32
Figure C.1 – Structure of a high current PCB . 34
Figure C.2 – PCB terminal block with soldered connection to the PCB . 35
Figure C.3 – PCB terminal block with screwed connection to the PCB . 35
Table 1 – Standard cross-sections of copper conductors . 12
Table 2 – Relationship between maximum cross-section and connecting capacity of
PCB terminal blocks. 13
Table 3 – Standards for clamping units and connecting methods . 14
Table 4 – Tightening torques for PCB terminal blocks with screw-type clamping units . 19
Table 5 – Impulse withstand test voltages . 21
Table 6 – Dielectric test voltages corresponding to the rated insulation voltage . 21
Table 7 – Length of connectable conductors and conductor loops . 24
Table 8 – Examples of cross-sectional distribution of interconnections on printed
circuit boards . 25
– 4 – IEC 60947-7-4:2019 RLV IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-4: Ancillary equipment –
PCB terminal blocks for copper 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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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.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition. A vertical bar appears in the margin wherever a change
has been made. Additions are in green text, deletions are in strikethrough red text.
International Standard IEC 60947-7-4 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2013. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) additional test for PCB terminal blocks with clamping units, where contact pressure is
transmitted through insulating materials;
b) tightening torques for screws now given in Table 4 of this document (previously given in
Table 4 of IEC 60947-1:2007); tightening torques added for an additional type of screw;
c) new criteria for verification of contact resistance introduced;
d) clarification in the description of the temperature-rise test (current-temperature derating);
corrections in the test sequence according to Figure 4.
The text of this International Standard is based on the following documents:
FDIS Report on voting
121A/255/FDIS 121A/265/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, published under the general title Low-voltage
switchgear and controlgear, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
– 6 – IEC 60947-7-4:2019 RLV IEC 2019
INTRODUCTION
This document IEC 60947-7-4 for PCB terminal blocks covers not only the terminal block
requirements in accordance with the IEC 60947-7 series but also takes into account the
specifications of connectors in accordance with IEC 61984 as the requirements for both
components are highly similar owing to equivalent applications.
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-4: Ancillary equipment –
PCB terminal blocks for copper conductors
1 General
1 Scope
This part of IEC 60947-7 specifies requirements for PCB terminal blocks primarily intended for
industrial or similar use.
Mounting and fixing on the printed circuit board is made by soldering, press-in or equivalent
methods to provide electrical and mechanical connection between copper conductors and the
printed circuit board.
This document applies to PCB terminal blocks intended to connect copper conductors, with or
2 2
without special preparation, having a cross-section between 0,05 0,08 mm and 300 mm
(AWG 30/ 28-600 kcmil), intended to be used in circuits of a rated voltage not exceeding
1 000 V AC up to 1 000 Hz or 1 500 V DC.
NOTE 1 Large-cross-section terminal blocks are dedicated to the specific design of high-current PCBs. The range
up to 300 mm is kept to cover any possible application. Examples of high current PCBs and PCB terminal blocks
are shown in Annex C.
NOTE 2 AWG is the abbreviation of “American Wire Gage” (Gage (US) = Gauge (UK)).
1 kcmil = 1 000 cmil;
1 cmil = 1 circular mil = surface of a circle having a diameter of 1 mil;
1 mil = 1/1 000 inch.
This document may can be used as a guide for special types of PCB terminal blocks with
components, such as disconnect units, integrated cartridge fuse-links and the like or with
other dimensions of conductors.
If applicable, in this document the term “clamping unit” is used instead of “terminal”. This is
taken into account in the case of references to IEC 60947-1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60068-2-20, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads
IEC 60352-1, Solderless connections – Part 1: Wrapped connections – General requirements,
test methods and practical guidance
IEC 60352-2, Solderless connections – Part 2: Crimped connections – General requirements,
test methods and practical guidance
– 8 – IEC 60947-7-4:2019 RLV IEC 2019
IEC 60352-3, Solderless connections – Part 3: Solderless accessible insulation displacement
connections – General requirements, test methods and practical guidance
IEC 60352-4, Solderless connections – Part 4: Solderless non-accessible insulation
displacement connections – General requirements, test methods and practical guidance
IEC 60352-5, Solderless connections – Part 5: Press-in connections – General requirements,
test methods and practical guidance
IEC 60352-6, Solderless connections – Part 6: Insulation piercing connections – General
requirements, test methods and practical guidance
IEC 60352-7, Solderless connections – Part 7: Spring clamp connections – General
requirements, test methods and practical guidance
IEC 60512-2-1, Connectors for electronic equipment – Tests and measurements – Part 2-1:
Electrical continuity and contact resistance tests – Test 2a: Contact resistance – Millivolt level
method
IEC 60512-2-2:2003, Connectors for electronic equipment – Tests and measurements –
Part 2-2: Electrical continuity and contact resistance tests – Test 2b: Contact resistance –
Specified test current method
IEC 60512-4-1, Connectors for electronic equipment – Tests and measurements – Part 4-1:
Voltage stress tests – Test 4a: Voltage proof
IEC 60512-5-2:2002, Connectors for electronic equipment – Tests and measurements –
Part 5-2: Current-carrying capacity tests – Test 5b: Current-temperature derating
IEC 60512-11-7, Connectors for electronic equipment – Tests and measurements – Part 11-7:
Climatic tests – Test 11g: Flowing mixed gas corrosion test
IEC 60512-11-9, Connectors for electronic equipment – Tests and measurements – Part 11-9:
Climatic tests – Test 11i: Dry heat
IEC 60512-11-10, Connectors for electronic equipment – Tests and measurements –
Part 11-10: Climatic tests – Test 11j: Cold
IEC 60695-2-10, Fire hazard testing – Part 2-10: Glowing/hot-wire based test methods –
Glow-wire apparatus and common test procedure
IEC 60695-2-11, Fire hazard testing – Part 2-11: Glowing/hot-wire based test methods –
Glow-wire flammability test method for end-products (GWEPT)
IEC 60695-2-12, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60695-2-13, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignition temperature (GWIT) test method for materials
IEC 60947-1:2007, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-1:2007/AMD1:2010
IEC 60947-1:2007/AMD2:2014
IEC 60998-2-3, Connecting devices for low-voltage circuits for household and similar
purposes – Part 2-3: Particular requirements for connecting devices as separate entities with
insulation-piercing clamping units
IEC 60999-1, Connecting devices – Electrical copper conductors – Safety requirements for
screw-type and screwless-type clamping units – Part 1: General requirements and particular
2 2
up to 35 mm (included)
requirements for clamping units for conductors from 0,2 mm
IEC 60999-2, Connecting devices – Electrical copper conductors – Safety requirements for
screw-type and screwless-type clamping units – Part 2: Particular requirements for clamping
2 2
units for conductors above 35 mm up to 300 mm (included)
IEC 61210, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
ISO 6988, Metallic and other non-organic coatings – Sulfur dioxide test with general
condensation of moisture
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in IEC 60947-1,
as well as the following, apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
printed circuit board
PCB
piece of insulating material with fixed metal traces to connect electronic components
Note 1 to entry: Printed circuit boards are typically subdivided according to:
• their structure (e.g. single- and double-sided, multilayers);
• the nature of the base material (e.g. rigid, flexible).
Note 2 to entry: This note applies to the French language only.
3.2
PCB terminal block
part intended to be mounted on a printed circuit board and carrying one or more mutually
insulated contact units and which provides an electrical and mechanical connection between
copper conductor and printed circuit board
3.3
rated current
current value assigned by the manufacturer, which the PCB terminal block can carry
continuously (without interruption) and simultaneously through all its poles connected with the
maximum cross-section, preferably at an ambient temperature of 40 °C, without the upper
limiting temperature being exceeded
3.4
contact unit
conductive part establishing the connection between printed circuit board and connectable
conductor(s)
– 10 – IEC 60947-7-4:2019 RLV IEC 2019
Note 1 to entry: See Annex A for description of the structure of a PCB terminal block.
3.5
upper limiting temperature
ULT
maximum temperature assigned by the manufacturer in the PCB terminal block as outcome
(sum) of the ambient temperature and the temperature-rise due to current flow, at which the
PCB terminal block is intended to be still operable
Note 1 to entry: At ambient temperature = ULT the available temperature rise due to current flow is zero, thus the
current carrying capacity of the PCB terminal block is zero.
Note 1 to entry: This note applies to the French language only.
3.6
lower limiting temperature
LLT
minimum temperature of a PCB terminal block assigned by the manufacturer, at which a PCB
terminal block is intended to operate
Note 1 to entry: This note applies to the French language only.
4 Classification
A distinction is made between various types of PCB terminal blocks, if applicable, as follows:
a) type of clamping unit (see 8.1.1);
b) ability to accept prepared conductors (see 2.3.28 of IEC 60947-1:2007/AMD1:2010);
c) type of electrical contact to the printed circuit board;
d) type of mechanical fastening to the printed circuit board;
e) number of poles;
f) pitch (centre to centre pin spacing);
g) contact unit with identical or dissimilar clamping units;
h) number of clamping units on each contact unit;
i) service conditions.
5 Characteristics
5.1 Summary of characteristics
The characteristics of a PCB terminal block are as follows:
• type of PCB terminal block (see 5.2);
• rated and limiting values (see 5.3).
5.2 Type of PCB terminal block
The following shall be stated:
• type of clamping units (see 8.1.1);
• type of contacting on the printed circuit board;
• number of clamping units.
5.3 Rated and limiting values
5.3.1 Rated voltages
Subclauses 4.3.1.2 and 4.3.1.3 of IEC 60947-1:2007 apply.
5.3.2 Rated current
Verification of the rated current specified by the manufacturer is carried out in accordance
with 9.4.5.
If an ambient temperature other than 40 °C is used for the definition of the rated current, the
manufacturer should state, in the technical documentation, the ambient temperature on which
the rating is based, with reference, if appropriate, to the derating curve defined in
IEC 60512-5-2.
The derating curve is obtained by applying a reduction factor of 0,8 in accordance with
IEC 60512-5-2. If another reduction factor is used, this shall be stated in the technical
documentation.
5.3.3 Standard cross-sections
The standard values for cross-sections of copper conductors to be used are given in Table 1.
– 12 – IEC 60947-7-4:2019 RLV IEC 2019
Table 1 – Standard cross-sections of copper conductors
Comparison between AWG/kcmil and metric sizes
Metric size ISO
Size Equivalent metric area
2 2
mm AWG/kcmil mm
a a a
0,05 30 0,05
0,08 28 0,08
0,14 26 0,13
0,2 24 0,205
0,34 22 0,324
0,5 20 0,519
0,75 18 0,82
1 – –
1,5 16 1,3
2,5 14 2,1
4 12 3,3
6 10 5,3
10 8 8,4
16 6 13,3
25 4 21,2
35 2 33,6
50 0 53,5
70 00 67,4
95 000 85
– 0000 107,2
120 250 (kcmil) 127
150 300 (kcmil) 152
185 350 (kcmil) 177
240 500 (kcmil) 253
300 600 (kcmil) 304
a
Outside the scope of this document and included for information only.
5.3.4 Maximum cross-section
The maximum cross-section shall be selected from the standard cross-sections given
in Table 1.
5.3.5 Connecting capacity
2 2
For PCB terminal blocks with a maximum cross-section between 0,05 0,08 mm and 35 mm
inclusive, the minimum range contained in Table 2 applies. The conductors may be rigid (solid
or stranded) or flexible. The manufacturer shall state the types and the maximum and
minimum cross-sections of conductors that can be connected and, if applicable, the number of
conductors simultaneously connectable to each clamping unit. The manufacturer shall also
state any necessary preparation of the end of the conductor.
Table 2 – Relationship between maximum cross-section
and connecting capacity of PCB terminal blocks
Maximum cross-section Connecting capacity
2 2
mm AWG/kcmil mm AWG
a a a a
0,05 30 0,05 30
0,08 28 0,05 – 0,08 30 – 28
0,14 26 0,05 – 0,08 – 0,14 30 – 28 – 26
0,2 24 0,08 – 0,14 – 0,2 28 – 26 – 24
0,34 22 0,14 – 0,2 – 0,34 26 – 24 – 22
0,5 20 0,2 – 0,34 – 0,5 24 – 22 – 20
0,75 18 0,34 – 0,5 – 0,75 22 – 20 – 18
1 – 0,5 – 0,75 – 1 –
1,5 16 0,75 – 1 – 1,5 20 – 18 – 16
2,5 14 1 – 1,5 – 2,5 18 – 16 – 14
4 12 1,5 – 2,5 – 4 16 – 14 – 12
6 10 2,5 – 4 – 6 14 – 12 – 10
10 8 4 – 6 – 10 12 – 10 – 8
16 6 6 – 10 – 16 10 – 8 – 6
25 4 10 – 16 – 25 8 – 6 – 4
35 2 16 – 25 – 35 6 – 4 – 2
50 0 25 – 35 – 50 4 – 2 – 0
70 00 35 – 50 – 70 2 – 0 – 00
95 000 50 – 70 – 95 0 – 00 – 000
– 0000 – 00 – 000 – 0000
120 250 70 – 95 – 120 000 – 0000 – 250
150 300 95 – 120 – 150 0000 – 250 – 300
185 350 120 – 150 – 185 250 – 300 – 350
– 400 – 300 – 350 – 400
240 500 150 – 185 – 240 350 – 400 – 500
300 600 185 – 240 – 300 400 – 500 – 600
a
Outside the scope of this document and included for information only.
6 Product information
6.1 Marking
A PCB terminal block shall be marked in a durable and legible manner with the following:
a) the name of the manufacturer or a trade mark by which the manufacturer can be readily
identified;
b) a type reference permitting its identification in order to obtain relevant information from
the manufacturer or their catalogue.
Very small PCB terminal blocks with a surface that cannot be marked shall be marked only in
accordance with a). In those cases, all specified information shall be marked on the smallest
packing unit.
– 14 – IEC 60947-7-4:2019 RLV IEC 2019
6.2 Additional information
The following information shall be stated by the manufacturer, if applicable, e.g. in the
manufacturer's data sheet or their catalogue or on the packing unit:
a) IEC 60947-7-4, if the manufacturer claims compliance with this document;
b) the maximum cross-section;
c) the connecting capacity, if different from Table 2, including the number of conductors
simultaneously connectable;
d) the rated current and the reduction factor to determine the derating curve if different from
0,8;
NOTE Unless otherwise specified, the rated current is preferably determined on four-pole contact units.
e) the rated insulation voltage (U );
i
f) the rated impulse withstand voltage (U ), when determined;
imp
g) service conditions, if different from those stated in Clause 7;
h) special preparation of the end of the conductor;
i) additional information to be specified stated in Annex B, if applicable.
7 Normal service, mounting and transport conditions
Clause 6 of IEC 60947-1:2007/AMD2:2014 applies.
8 Constructional and performance requirements
8.1 Constructional requirements
8.1.1 Clamping units
The clamping units shall allow the conductors to be connected by means ensuring that a
reliable mechanical linkage and electrical contact is properly maintained.
No contact pressure shall be transmitted through insulating materials other than ceramic, or
other material with characteristics not less suitable, unless there is sufficient resiliency in the
metallic parts to compensate for any possible shrinkage of the insulating material.
The corresponding test is under consideration.
Clamping units and connecting methods listed in Table 3 fulfil the requirements of this
standard.
In addition, the test described in 9.4.7.3 shall be performed if contact pressure of the
clamping unit is transmitted through insulating material. If this contact pressure is transmitted
purely via ceramic or pure mica, the test according to 9.4.7.3 is not deemed necessary.
Clamping units and connecting methods listed in Table 3 fulfil the mechanical requirements of
this document.
Additional requirements are given in this document.
Other terminations and connection methods shall be tested in accordance with the relevant
standards.
Table 3 – Standards for clamping units and connecting methods
Ref. Clamping units and connecting methods Reference standards
a) Screw-type clamping unit IEC 60999-1 or IEC 60999-2
b) Screwless-type clamping unit IEC 60999-1 or IEC 60999-2 or IEC 60352-7
c) Wrapped connection IEC 60352-1
d) Crimped connection IEC 60352-2
e) Insulation displacement connection (accessible) IEC 60352-3 or IEC 60998-2-3
f) Insulation displacement connection IEC 60352-4 or IEC 60998-2-3
(non accessible)
g) Press-in connection IEC 60352-5
h) Insulation piercing connection IEC 60352-6 or IEC 60998-2-3
i) Flat quick-connect termination IEC 61210
a
j) Soldered connection IEC 60068-2-20
NOTE The relevant standard applies for the preconditioning of prepared conductors.
a
The test method selected shall be stated in the test report.
8.1.2 Mounting and installation
PCB terminal blocks shall be so designed that safe mounting on a printed circuit board is
possible by means of soldering, pressing-in, screwing, etc. The connection to the printed
circuit board shall not be damaged by connecting the conductors.
Tests shall be carried out in accordance with 9.3.2.
8.1.3 Clearances and creepage distances
For PCB terminal blocks for which the manufacturer has stated values of rated impulse
) and rated insulation voltage (U ), minimum values of clearances and
withstand voltage (U
imp i
creepage distances are given in Table 13 of IEC 60947-1:2007 and Table 15 of
IEC 60947-1:2007/AMD1:2010.
For PCB terminal blocks for which the manufacturer has not declared a value of rated impulse
withstand voltage (U ), guidance for minimum values is given in Annex H of
imp
IEC 60947-1:2007.
Electrical requirements are given in 8.2.2.
8.1.4 Terminal identification and marking
Subclause 7.1.8.4 of IEC 60947-1:2007 applies with the following addition.
A PCB terminal block shall have provision, or at least space, for identification marks or
numbers for each clamping unit or contact unit related to the circuit of which it forms a part,
except when such marking is not physically possible.
If such marking is not possible the information shall be stated by the manufacturer, e.g. in the
manufacturer's data sheet or his catalogue or on the packing unit.
Such provision may consist of separate marking items, such as marking tags, identification
labels, etc.
– 16 – IEC 60947-7-4:2019 RLV IEC 2019
8.1.5 Resistance to abnormal heat and fire
The insulation materials of PCB terminal blocks shall not be adversely affected by abnormal
heat and fire.
Compliance is checked by:
a) the glow-wire test on the complete product in accordance with 9.5 or
b) verification of the insulating material in accordance with
1) IEC 60695-2-12, method GWFI at a temperature of 850 °C, or
2) IEC 60695-2-13, method GWIT at a temperature of 775 °C.
This verification is not necessary for small parts (see IEC 60695-2-11).
NOTE 1 The relevant test method is specified by the manufacturer.
NOTE 2 For some applications it may can be mandatory to check compliance by the glow-wire test on the
complete product in accordance with 9.5 only. The need is either defined in the end-product standard or by
agreement between the manufacturer and the users. See Clause B.1.
8.1.6 Maximum cross-section and connecting capacity
PCB terminal blocks shall be so designed that conductors of the maximum cross-section and
the connecting capacity, if applicable, can be accepted.
Compliance is checked by the test described in 9.3.4.
The verification of the maximum cross-section may be performed by the special test in
accordance with 9.3.5.
8.2 Performance requirements
8.2.1 Temperature-rise (current-temperature derating)
PCB terminal blocks shall be tested in accordance with 9.4.5. The sum of ambient
temperature and temperature-rise of the PCB terminal block shall not exceed the upper
limiting temperature (ULT).
8.2.2 Dielectric properties
If the manufacturer has declared a value of the rated impulse withstand voltage (U )
imp
(see 4.3.1.3 of IEC 60947-1:2007), the requirements of 7.2.3 and 7.2.3.1 of
IEC 60947-1:2007/AMD1:2010 apply. If applicable, the impulse withstand voltage test shall be
carried out in accordance with 9.4.3a).
For the verification of solid insulation the power-frequency withstand voltage test shall be
carried out in accordance with 9.4.3b).
The verification of sufficient clearances and creepage distances shall be made in accordance
with 9.4.2. For PCB terminal blocks for which the manufacturer has not declared a value of
rated impulse withstand voltage (U ), guidance for minimum values is given in Annex H of
imp
IEC 60947-1:2007.
8.2.3 Short-time withstand current
A PCB terminal block shall be capable of withstanding the short-time withstand current which
corresponds to 120 A/mm for 1 s, in accordance with 9.4.6.
The test shall be performed using the smallest cross-section in the current path of the contact
unit as declared by the manufacturer.
8.2.4 Contact resistance
When measured in accordance with 9.4.4, the change in contact resistance of a PCB terminal
block caused by the conductor connection and the mounting on the printed circuit board shall
not exceed the permissible deviations.
8.2.5 Ageing tests
8.2.5.1 Climatic sequence and corrosion test
For the verification of the resistance of connections against the influence of temperatures and
corrosive atmospheres, the climatic sequence test shall be carried out for all kinds of PCB
terminal blocks.
Compliance is checked by the test described in 9.4.7.1.
8.2.5.2 Ageing test for screwless-type PCB terminal blocks
For the verification of screwless-type PCB terminal blocks the ageing test shall be carried out.
Compliance is checked by the test described in 9.4.7.2 (if relevant).
For screwless-type PCB terminal blocks with contact pressure via insulating material, only the
current cycling ageing test in accordance with 9.4.7.3 shall be performed.
8.2.5.3 Current cycling ageing test for PCB terminal blocks with contact pressure via
insulating material
For the verification of the resistance of connections against the influence of contact pressure
via insulating material, the current cycling ageing test shall be carried out.
Compliance is checked by the test described in 9.4.7.3 (if relevant).
8.3 Electromagnetic compatibility (EMC)
Subclause 7.3 of IEC 60947-1:2007, IEC 60947-1:2007/AMD1:2010 and IEC 60947-1:2007/
AMD2:2014 applies.
9 Tests
9.1 Kinds of test
Subclause 8.1.1 of IEC 60947-1:2007 applies with the following addition.
No routine tests are specified. The verification of the maximum cross-section in accordance
with 9.3.5 is a special test. All other tests are type tests.
9.2 General
Unless otherwise specified, PCB terminal blocks are tested in new and in clean condition, and
installed as for normal use (see 6.3 of IEC 60947-1:2007) at an ambient temperature of
(25 ±10) °C.
The tests are carried out in the order described in 9.3, 9.4 and 9.5.
– 18 – IEC 60947-7-4:2019 RLV IEC 2019
Each test is carried out on new individual specimens with at least four contact units (one set)
where each multipole PCB terminal block may contain the required number of contact units.
For a PCB terminal block family with the same design and comparable form, tests need only
be performed on specimens representing the most unfavourable case.
The surface of the conductors shall be free of contamination and corrosion that degrades
performance.
Care shall be taken when stripping conductors to avoid cutting, nicking, scraping or otherwise
damaging the conductors.
In cases where the manufacturer has stated that special preparation of the end of the
conductor is necessary, the test report shall indicate the method of preparation used.
The tests are carried out with the type of conductors (rigid or flexible) as stated by the
manufacturer.
If one of the PCB terminal blocks does not withstand one of the tests, this test shall be
repeated on a second set of PCB terminal blocks, all of which shall then comply with the
repeated test. If this test is part of a test sequence, the complete test sequence shall be
repeated.
9.3 Verification of mechanical characteristics
9.3.1 General
The verification of mechanical characteristics includes the following test:
• attachment of the PCB terminal block on its support (see 9.3.2);
• verification of the maximum cross-s
...
IEC 60947-7-4 ®
Edition 2.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
Appareillage à basse tension –
Partie 7-4: Matériels accessoires – Blocs de jonction pour cartes de circuits
imprimés pour conducteurs en cuivre
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IEC 60947-7-4 ®
Edition 2.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 7-4: Ancillary equipment – PCB terminal blocks for copper conductors
Appareillage à basse tension –
Partie 7-4: Matériels accessoires – Blocs de jonction pour cartes de circuits
imprimés pour conducteurs en cuivre
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-6402-7
– 2 – IEC 60947-7-4:2019 IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 9
4 Classification . 10
5 Characteristics . 10
5.1 Summary of characteristics . 10
5.2 Type of PCB terminal block . 10
5.3 Rated and limiting values . 10
5.3.1 Rated voltages . 10
5.3.2 Rated current . 11
5.3.3 Standard cross-sections . 11
5.3.4 Maximum cross-section . 12
5.3.5 Connecting capacity . 12
6 Product information . 13
6.1 Marking . 13
6.2 Additional information . 13
7 Normal service, mounting and transport conditions . 13
8 Constructional and performance requirements . 13
8.1 Constructional requirements . 13
8.1.1 Clamping units . 13
8.1.2 Mounting and installation . 14
8.1.3 Clearances and creepage distances . 14
8.1.4 Terminal identification and marking . 14
8.1.5 Resistance to abnormal heat and fire . 15
8.1.6 Maximum cross-section and connecting capacity . 15
8.2 Performance requirements . 15
8.2.1 Temperature-rise (current-temperature derating) . 15
8.2.2 Dielectric properties . 15
8.2.3 Short-time withstand current . 15
8.2.4 Contact resistance . 16
8.2.5 Ageing tests . 16
8.3 Electromagnetic compatibility (EMC) . 16
9 Tests . 16
9.1 Kinds of test . 16
9.2 General . 16
9.3 Verification of mechanical characteristics . 17
9.3.1 General . 17
9.3.2 Attachment of the PCB terminal block on its support . 17
9.3.3 Vacant . 18
9.3.4 Verification of the maximum cross-section and connecting capacity . 18
9.3.5 Verification of maximum cross-section (special test with gauges) . 18
9.4 Verification of electrical characteristics . 19
9.4.1 General . 19
9.4.2 Verification of clearances and creepage distances . 19
9.4.3 Dielectric tests . 19
9.4.4 Verification of contact resistance . 20
9.4.5 Temperature-rise test (current-temperature derating) . 22
9.4.6 Short-time withstand current test . 24
9.4.7 Ageing tests . 25
9.5 Verification of thermal characteristics. 29
9.6 Verification of EMC characteristics . 30
9.6.1 General . 30
9.6.2 Immunity . 30
9.6.3 Emission . 30
Annex A (informative) Structure of a PCB terminal block . 31
Annex B (informative) Additional information to be specified between the manufacturer
and the user . 32
B.1 Additional information available on request of the user . 32
B.2 Information for testing in addition to those mentioned above . 32
Annex C (informative) Examples of PCBs and PCB terminal blocks for high-current
application . 33
C.1 Layout of high-current PCBs (schematic diagram) . 33
C.2 High-current PCB terminal blocks . 34
Bibliography . 35
Figure 1 – Test assembly for the measurement of contact resistance and temperature-rise . 22
Figure 2 – Example of wiring structure of a multi-tier PCB terminal block . 23
Figure 3 – Test assembly for the measurement of short-time withstand current . 25
Figure 4 – Test sequence . 26
Figure 5 – Test sequence for PCB terminal blocks with contact pressure via insulating
material . 27
Figure 6 – Current cycling ageing test procedure . 29
Figure A.1 – Structure of a PCB terminal block . 31
Figure C.1 – Structure of a high current PCB . 33
Figure C.2 – PCB terminal block with soldered connection to the PCB . 34
Figure C.3 – PCB terminal block with screwed connection to the PCB . 34
Table 1 – Standard cross-sections of copper conductors . 11
Table 2 – Relationship between maximum cross-section and connecting capacity of
PCB terminal blocks. 12
Table 3 – Standards for clamping units and connecting methods . 14
Table 4 – Tightening torques for PCB terminal blocks with screw-type clamping units . 18
Table 5 – Impulse withstand test voltages . 20
Table 6 – Dielectric test voltages corresponding to the rated insulation voltage . 20
Table 7 – Length of connectable conductors and conductor loops . 23
Table 8 – Examples of cross-sectional distribution of interconnections on printed
circuit boards . 24
– 4 – IEC 60947-7-4:2019 IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-4: Ancillary equipment –
PCB terminal blocks for copper 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
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
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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 60947-7-4 has been prepared by subcommittee 121A: Low-voltage
switchgear and controlgear, of IEC technical committee 121: Switchgear and controlgear and
their assemblies for low voltage.
This second edition cancels and replaces the first edition published in 2013. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) additional test for PCB terminal blocks with clamping units, where contact pressure is
transmitted through insulating materials;
b) tightening torques for screws now given in Table 4 of this document (previously given in
Table 4 of IEC 60947-1:2007); tightening torques added for an additional type of screw;
c) new criteria for verification of contact resistance introduced;
d) clarification in the description of the temperature-rise test (current-temperature derating);
corrections in the test sequence according to Figure 4.
The text of this International Standard is based on the following documents:
FDIS Report on voting
121A/255/FDIS 121A/265/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, published under the general title Low-voltage
switchgear and controlgear, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
– 6 – IEC 60947-7-4:2019 IEC 2019
INTRODUCTION
This document covers not only the terminal block requirements in accordance with the
IEC 60947-7 series but also takes into account the specifications of connectors in accordance
with IEC 61984 as the requirements for both components are highly similar owing to
equivalent applications.
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-4: Ancillary equipment –
PCB terminal blocks for copper conductors
1 Scope
This part of IEC 60947-7 specifies requirements for PCB terminal blocks primarily intended for
industrial or similar use.
Mounting and fixing on the printed circuit board is made by soldering, press-in or equivalent
methods to provide electrical and mechanical connection between copper conductors and the
printed circuit board.
This document applies to PCB terminal blocks intended to connect copper conductors, with or
2 2
without special preparation, having a cross-section between 0,08 mm and 300 mm
(AWG 28-600 kcmil), intended to be used in circuits of a rated voltage not exceeding
1 000 V AC up to 1 000 Hz or 1 500 V DC.
NOTE 1 Large-cross-section terminal blocks are dedicated to the specific design of high-current PCBs. The range
up to 300 mm is kept to cover any possible application. Examples of high current PCBs and PCB terminal blocks
are shown in Annex C.
NOTE 2 AWG is the abbreviation of “American Wire Gage” (Gage (US) = Gauge (UK)).
1 kcmil = 1 000 cmil;
1 cmil = 1 circular mil = surface of a circle having a diameter of 1 mil;
1 mil = 1/1 000 inch.
This document can be used as a guide for special types of PCB terminal blocks with
components, such as disconnect units, integrated cartridge fuse-links and the like or with
other dimensions of conductors.
If applicable, in this document the term “clamping unit” is used instead of “terminal”. This is
taken into account in the case of references to IEC 60947-1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60068-2-20, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads
IEC 60352-1, Solderless connections – Part 1: Wrapped connections – General requirements,
test methods and practical guidance
IEC 60352-2, Solderless connections – Part 2: Crimped connections – General requirements,
test methods and practical guidance
– 8 – IEC 60947-7-4:2019 IEC 2019
IEC 60352-3, Solderless connections – Part 3: Solderless accessible insulation displacement
connections – General requirements, test methods and practical guidance
IEC 60352-4, Solderless connections – Part 4: Solderless non-accessible insulation
displacement connections – General requirements, test methods and practical guidance
IEC 60352-5, Solderless connections – Part 5: Press-in connections – General requirements,
test methods and practical guidance
IEC 60352-6, Solderless connections – Part 6: Insulation piercing connections – General
requirements, test methods and practical guidance
IEC 60352-7, Solderless connections – Part 7: Spring clamp connections – General
requirements, test methods and practical guidance
IEC 60512-2-2:2003, Connectors for electronic equipment – Tests and measurements –
Part 2-2: Electrical continuity and contact resistance tests – Test 2b: Contact resistance –
Specified test current method
IEC 60512-4-1, Connectors for electronic equipment – Tests and measurements – Part 4-1:
Voltage stress tests – Test 4a: Voltage proof
IEC 60512-5-2:2002, Connectors for electronic equipment – Tests and measurements –
Part 5-2: Current-carrying capacity tests – Test 5b: Current-temperature derating
IEC 60512-11-7, Connectors for electronic equipment – Tests and measurements – Part 11-7:
Climatic tests – Test 11g: Flowing mixed gas corrosion test
IEC 60512-11-9, Connectors for electronic equipment – Tests and measurements – Part 11-9:
Climatic tests – Test 11i: Dry heat
IEC 60512-11-10, Connectors for electronic equipment – Tests and measurements –
Part 11-10: Climatic tests – Test 11j: Cold
IEC 60695-2-10, Fire hazard testing – Part 2-10: Glowing/hot-wire based test methods –
Glow-wire apparatus and common test procedure
IEC 60695-2-11, Fire hazard testing – Part 2-11: Glowing/hot-wire based test methods –
Glow-wire flammability test method for end-products (GWEPT)
IEC 60695-2-12, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability index (GWFI) test method for materials
IEC 60695-2-13, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignition temperature (GWIT) test method for materials
voltage switchgear and controlgear – Part 1: General rules
IEC 60947-1:2007, Low-
IEC 60947-1:2007/AMD1:2010
IEC 60947-1:2007/AMD2:2014
IEC 60998-2-3, Connecting devices for low-voltage circuits for household and similar
purposes – Part 2-3: Particular requirements for connecting devices as separate entities with
insulation-piercing clamping units
IEC 60999-1, Connecting devices – Electrical copper conductors – Safety requirements for
screw-type and screwless-type clamping units – Part 1: General requirements and particular
2 2
requirements for clamping units for conductors from 0,2 mm up to 35 mm (included)
IEC 60999-2, Connecting devices – Electrical copper conductors – Safety requirements for
screw-type and screwless-type clamping units – Part 2: Particular requirements for clamping
2 2
up to 300 mm (included)
units for conductors above 35 mm
IEC 61210, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
ISO 6988, Metallic and other non-organic coatings – Sulfur dioxide test with general
condensation of moisture
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
printed circuit board
PCB
piece of insulating material with fixed metal traces to connect electronic components
Note 1 to entry: Printed circuit boards are typically subdivided according to:
• their structure (e.g. single- and double-sided, multilayers);
• the nature of the base material (e.g. rigid, flexible).
Note 2 to entry: This note applies to the French language only.
3.2
PCB terminal block
part intended to be mounted on a printed circuit board and carrying one or more mutually
insulated contact units and which provides an electrical and mechanical connection between
copper conductor and printed circuit board
3.3
rated current
current value assigned by the manufacturer, which the PCB terminal block can carry
continuously (without interruption) and simultaneously through all its poles connected with the
maximum cross-section, preferably at an ambient temperature of 40 °C, without the upper
limiting temperature being exceeded
3.4
contact unit
conductive part establishing the connection between printed circuit board and connectable
conductor(s)
Note 1 to entry: See Annex A for description of the structure of a PCB terminal block.
– 10 – IEC 60947-7-4:2019 IEC 2019
3.5
upper limiting temperature
ULT
maximum temperature assigned by the manufacturer in the PCB terminal block as outcome
(sum) of the ambient temperature and the temperature-rise due to current flow, at which the
PCB terminal block is intended to be still operable
Note 1 to entry: This note applies to the French language only.
3.6
lower limiting temperature
LLT
minimum temperature of a PCB terminal block assigned by the manufacturer, at which a PCB
terminal block is intended to operate
Note 1 to entry: This note applies to the French language only.
4 Classification
A distinction is made between various types of PCB terminal blocks, if applicable, as follows:
a) type of clamping unit (see 8.1.1);
b) ability to accept prepared conductors (see 2.3.28 of IEC 60947-1:2007/AMD1:2010);
c) type of electrical contact to the printed circuit board;
d) type of mechanical fastening to the printed circuit board;
e) number of poles;
f) pitch (centre to centre pin spacing);
g) contact unit with identical or dissimilar clamping units;
h) number of clamping units on each contact unit;
i) service conditions.
5 Characteristics
5.1 Summary of characteristics
The characteristics of a PCB terminal block are as follows:
• type of PCB terminal block (see 5.2);
• rated and limiting values (see 5.3).
5.2 Type of PCB terminal block
The following shall be stated:
• type of clamping units (see 8.1.1);
• type of contacting on the printed circuit board;
• number of clamping units.
5.3 Rated and limiting values
5.3.1 Rated voltages
Subclauses 4.3.1.2 and 4.3.1.3 of IEC 60947-1:2007 apply.
5.3.2 Rated current
Verification of the rated current specified by the manufacturer is carried out in accordance
with 9.4.5.
If an ambient temperature other than 40 °C is used for the definition of the rated current, the
manufacturer should state, in the technical documentation, the ambient temperature on which
the rating is based, with reference, if appropriate, to the derating curve defined in
IEC 60512-5-2.
The derating curve is obtained by applying a reduction factor of 0,8 in accordance with
IEC 60512-5-2. If another reduction factor is used, this shall be stated in the technical
documentation.
5.3.3 Standard cross-sections
The standard values for cross-sections of copper conductors to be used are given in Table 1.
Table 1 – Standard cross-sections of copper conductors
Comparison between AWG/kcmil and metric sizes
Metric size ISO
Size Equivalent metric area
2 2
mm AWG/kcmil mm
a a a
0,05 30 0,05
0,08 28 0,08
0,14 26 0,13
0,2 24 0,205
0,34 22 0,324
0,5 20 0,519
0,75 18 0,82
1 – –
1,5 16 1,3
2,5 14 2,1
4 12 3,3
6 10 5,3
10 8 8,4
16 6 13,3
25 4 21,2
35 2 33,6
50 0 53,5
70 00 67,4
95 000 85
– 0000 107,2
120 250 (kcmil) 127
150 300 (kcmil) 152
185 350 (kcmil) 177
240 500 (kcmil) 253
300 600 (kcmil) 304
a
Outside the scope of this document and included for information only.
– 12 – IEC 60947-7-4:2019 IEC 2019
5.3.4 Maximum cross-section
The maximum cross-section shall be selected from the standard cross-sections given
in Table 1.
5.3.5 Connecting capacity
2 2
For PCB terminal blocks with a maximum cross-section between 0,08 mm and 35 mm
inclusive, the minimum range contained in Table 2 applies. The conductors may be rigid (solid
or stranded) or flexible. The manufacturer shall state the types and the maximum and
minimum cross-sections of conductors that can be connected and, if applicable, the number of
conductors simultaneously connectable to each clamping unit. The manufacturer shall also
state any necessary preparation of the end of the conductor.
Table 2 – Relationship between maximum cross-section
and connecting capacity of PCB terminal blocks
Maximum cross-section Connecting capacity
2 2
mm AWG/kcmil mm AWG
a a a a
0,05 30 0,05 30
0,08 28 0,05 – 0,08 30 – 28
0,14 26 0,05 – 0,08 – 0,14 30 – 28 – 26
0,2 24 0,08 – 0,14 – 0,2 28 – 26 – 24
0,34 22 0,14 – 0,2 – 0,34 26 – 24 – 22
0,5 20 0,2 – 0,34 – 0,5 24 – 22 – 20
0,75 18 0,34 – 0,5 – 0,75 22 – 20 – 18
1 – 0,5 – 0,75 – 1 –
1,5 16 0,75 – 1 – 1,5 20 – 18 – 16
2,5 14 1 – 1,5 – 2,5 18 – 16 – 14
4 12 1,5 – 2,5 – 4 16 – 14 – 12
6 10 2,5 – 4 – 6 14 – 12 – 10
10 8 4 – 6 – 10 12 – 10 – 8
16 6 6 – 10 – 16 10 – 8 – 6
25 4 10 – 16 – 25 8 – 6 – 4
35 2 16 – 25 – 35 6 – 4 – 2
50 0 25 – 35 – 50 4 – 2 – 0
70 00 35 – 50 – 70 2 – 0 – 00
95 000 50 – 70 – 95 0 – 00 – 000
– 0000 – 00 – 000 – 0000
120 250 70 – 95 – 120 000 – 0000 – 250
150 300 95 – 120 – 150 0000 – 250 – 300
185 350 120 – 150 – 185 250 – 300 – 350
– 400 – 300 – 350 – 400
240 500 150 – 185 – 240 350 – 400 – 500
300 600 185 – 240 – 300 400 – 500 – 600
a
Outside the scope of this document and included for information only.
6 Product information
6.1 Marking
A PCB terminal block shall be marked in a durable and legible manner with the following:
a) the name of the manufacturer or a trade mark by which the manufacturer can be readily
identified;
b) a type reference permitting its identification in order to obtain relevant information from
the manufacturer or their catalogue.
Very small PCB terminal blocks with a surface that cannot be marked shall be marked only in
accordance with a). In those cases, all specified information shall be marked on the smallest
packing unit.
6.2 Additional information
The following information shall be stated by the manufacturer, if applicable, e.g. in the
manufacturer's data sheet or their catalogue or on the packing unit:
a) IEC 60947-7-4, if the manufacturer claims compliance with this document;
b) the maximum cross-section;
c) the connecting capacity, if different from Table 2, including the number of conductors
simultaneously connectable;
d) the rated current and the reduction factor to determine the derating curve if different from
0,8;
NOTE Unless otherwise specified, the rated current is preferably determined on four-pole contact units.
e) the rated insulation voltage (U );
i
f) the rated impulse withstand voltage (U ), when determined;
imp
g) service conditions, if different from those stated in Clause 7;
h) special preparation of the end of the conductor;
i) additional information to be specified stated in Annex B, if applicable.
7 Normal service, mounting and transport conditions
Clause 6 of IEC 60947-1:2007/AMD2:2014 applies.
8 Constructional and performance requirements
8.1 Constructional requirements
8.1.1 Clamping units
The clamping units shall allow the conductors to be connected by means ensuring that a
reliable mechanical linkage and electrical contact is properly maintained.
In addition, the test described in 9.4.7.3 shall be performed if contact pressure of the
clamping unit is transmitted through insulating material. If this contact pressure is transmitted
purely via ceramic or pure mica, the test according to 9.4.7.3 is not deemed necessary.
Clamping units and connecting methods listed in Table 3 fulfil the mechanical requirements of
this document.
Additional requirements are given in this document.
– 14 – IEC 60947-7-4:2019 IEC 2019
Other terminations and connection methods shall be tested in accordance with the relevant
standards.
Table 3 – Standards for clamping units and connecting methods
Ref. Clamping units and connecting methods Reference standards
a) Screw-type clamping unit IEC 60999-1 or IEC 60999-2
b) Screwless-type clamping unit IEC 60999-1 or IEC 60999-2 or IEC 60352-7
c) Wrapped connection IEC 60352-1
d) Crimped connection IEC 60352-2
e) Insulation displacement connection (accessible) IEC 60352-3 or IEC 60998-2-3
f) Insulation displacement connection IEC 60352-4 or IEC 60998-2-3
(non accessible)
g) Press-in connection IEC 60352-5
h) Insulation piercing connection IEC 60352-6 or IEC 60998-2-3
i) Flat quick-connect termination IEC 61210
a
j) Soldered connection IEC 60068-2-20
NOTE The relevant standard applies for the preconditioning of prepared conductors.
a
The test method selected shall be stated in the test report.
8.1.2 Mounting and installation
PCB terminal blocks shall be so designed that safe mounting on a printed circuit board is
possible by means of soldering, pressing-in, screwing, etc. The connection to the printed
circuit board shall not be damaged by connecting the conductors.
Tests shall be carried out in accordance with 9.3.2.
8.1.3 Clearances and creepage distances
For PCB terminal blocks for which the manufacturer has stated values of rated impulse
withstand voltage (U ) and rated insulation voltage (U ), minimum values of clearances and
imp i
creepage distances are given in Table 13 of IEC 60947-1:2007 and Table 15 of
IEC 60947-1:2007/AMD1:2010.
For PCB terminal blocks for which the manufacturer has not declared a value of rated impulse
), guidance for minimum values is given in Annex H of
withstand voltage (U
imp
IEC 60947-1:2007.
Electrical requirements are given in 8.2.2.
8.1.4 Terminal identification and marking
Subclause 7.1.8.4 of IEC 60947-1:2007 applies with the following addition.
A PCB terminal block shall have provision, or at least space, for identification marks or
numbers for each clamping unit or contact unit related to the circuit of which it forms a part,
except when such marking is not physically possible.
Such provision may consist of separate marking items, such as marking tags, identification
labels, etc.
8.1.5 Resistance to abnormal heat and fire
The insulation materials of PCB terminal blocks shall not be adversely affected by abnormal
heat and fire.
Compliance is checked by:
a) the glow-wire test on the complete product in accordance with 9.5 or
b) verification of the insulating material in accordance with
1) IEC 60695-2-12, method GWFI at a temperature of 850 °C, or
2) IEC 60695-2-13, method GWIT at a temperature of 775 °C.
This verification is not necessary for small parts (see IEC 60695-2-11).
NOTE 1 The relevant test method is specified by the manufacturer.
NOTE 2 For some applications it can be mandatory to check compliance by the glow-wire test on the complete
product in accordance with 9.5 only. The need is either defined in the end-product standard or by agreement
between the manufacturer and the users. See Clause B.1.
8.1.6 Maximum cross-section and connecting capacity
PCB terminal blocks shall be so designed that conductors of the maximum cross-section and
the connecting capacity, if applicable, can be accepted.
Compliance is checked by the test described in 9.3.4.
The verification of the maximum cross-section may be performed by the special test in
accordance with 9.3.5.
8.2 Performance requirements
8.2.1 Temperature-rise (current-temperature derating)
PCB terminal blocks shall be tested in accordance with 9.4.5. The sum of ambient
temperature and temperature-rise of the PCB terminal block shall not exceed the upper
limiting temperature.
8.2.2 Dielectric properties
If the manufacturer has declared a value of the rated impulse withstand voltage (U )
imp
(see 4.3.1.3 of IEC 60947-1:2007), the requirements of 7.2.3 and 7.2.3.1 of
IEC 60947-1:2007/AMD1:2010 apply. If applicable, the impulse withstand voltage test shall be
carried out in accordance with 9.4.3a).
For the verification of solid insulation the power-frequency withstand voltage test shall be
carried out in accordance with 9.4.3b).
The verification of sufficient clearances and creepage distances shall be made in accordance
with 9.4.2. For PCB terminal blocks for which the manufacturer has not declared a value of
rated impulse withstand voltage (U ), guidance for minimum values is given in Annex H of
imp
IEC 60947-1:2007.
8.2.3 Short-time withstand current
A PCB terminal block shall be capable of withstanding the short-time withstand current which
corresponds to 120 A/mm for 1 s, in accordance with 9.4.6.
– 16 – IEC 60947-7-4:2019 IEC 2019
The test shall be performed using the smallest cross-section in the current path of the contact
unit as declared by the manufacturer.
8.2.4 Contact resistance
When measured in accordance with 9.4.4, the change in contact resistance of a PCB terminal
block caused by the conductor connection and the mounting on the printed circuit board shall
not exceed the permissible deviations.
8.2.5 Ageing tests
8.2.5.1 Climatic sequence and corrosion test
For the verification of the resistance of connections against the influence of temperatures and
corrosive atmospheres, the climatic sequence test shall be carried out for all kinds of PCB
terminal blocks.
Compliance is checked by the test described in 9.4.7.1.
8.2.5.2 Ageing test for screwless-type PCB terminal blocks
For the verification of screwless-type PCB terminal blocks the ageing test shall be carried out.
Compliance is checked by the test described in 9.4.7.2 (if relevant).
For screwless-type PCB terminal blocks with contact pressure via insulating material, only the
current cycling ageing test in accordance with 9.4.7.3 shall be performed.
8.2.5.3 Current cycling ageing test for PCB terminal blocks with contact pressure via
insulating material
For the verification of the resistance of connections against the influence of contact pressure
via insulating material, the current cycling ageing test shall be carried out.
Compliance is checked by the test described in 9.4.7.3 (if relevant).
8.3 Electromagnetic compatibility (EMC)
Subclause 7.3 of IEC 60947-1:2007, IEC 60947-1:2007/AMD1:2010 and IEC 60947-1:2007/
AMD2:2014 applies.
9 Tests
9.1 Kinds of test
Subclause 8.1.1 of IEC 60947-1:2007 applies with the following addition.
No routine tests are specified. The verification of the maximum cross-section in accordance
with 9.3.5 is a special test. All other tests are type tests.
9.2 General
Unless otherwise specified, PCB terminal blocks are tested in new and in clean condition, and
installed as for normal use (see 6.3 of IEC 60947-1:2007) at an ambient temperature of
(25 ±10) °C.
The tests are carried out in the order described in 9.3, 9.4 and 9.5.
Each test is carried out on new individual s
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