Low-voltage switchgear and controlgear - Part 7-5: Ancillary equipment - Terminal blocks for aluminium conductors

IEC TS 60947-7-5:2021 specifies requirements for terminal blocks with screw-type or screwless-type clamping units primarily intended for industrial or similar use and to be fixed to a support to provide electrical and mechanical connection. This document can be used for terminal blocks for connection between aluminium conductors or aluminium to copper conductors. It applies to terminal blocks intended to connect round conductors, with or without special preparation, having a cross-section between 2,5 mm2 and 300 mm2 (AWG 12 to 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.

Appareillage à basse tension - Partie 7-5: Matériels accessoires - Blocs de jonction pour conducteurs en aluminium

L'IEC TS 60947-7-5:2021 spécifie les exigences relatives aux blocs de jonction avec organes de serrage du type à vis ou du type sans vis essentiellement destinés à un usage industriel ou analogue, et à être fixés sur un support afin d'assurer la connexion électrique et mécanique. Le présent document peut être utilisé pour les blocs de jonction qui assurent le raccordement entre des conducteurs en aluminium ou entre des conducteurs en aluminium et en cuivre. Il s'applique aux blocs de jonction destinés à raccorder les conducteurs ronds, avec ou sans préparation particulière, dont la section est comprise entre 2,5 mm2 et 300 mm2 (AWG 12 à 600 kcmil) et destinés à être utilisés dans des circuits présentant une tension assignée maximale de 1 000 V en courant alternatif (jusqu'à 1 000 Hz) ou de 1 500 V en courant continu.

General Information

Status
Published
Publication Date
21-Nov-2021
Current Stage
PPUB - Publication issued
Completion Date
22-Nov-2021
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IEC TS 60947-7-5
Edition 1.0 2021-11
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
colour
inside
Low-voltage switchgear and controlgear –
Part 7-5: Ancillary equipment – Terminal blocks for aluminium conductors
Appareillage à basse tension –
Partie 7-5: Matériels accessoires – Blocs de jonction pour conducteurs en
aluminium
IEC TS 60947-7-5:2021-11(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 60947-7-5
Edition 1.0 2021-11
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
colour
inside
Low-voltage switchgear and controlgear –
Part 7-5: Ancillary equipment – Terminal blocks for aluminium conductors
Appareillage à basse tension –
Partie 7-5: Matériels accessoires – Blocs de jonction pour conducteurs en
aluminium
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-1041-9

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC TS 60947-7-5:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 Classification ................................................................................................................... 9

5 Characteristics .............................................................................................................. 10

5.1 Summary of characteristics ................................................................................... 10

5.2 Type of terminal block ........................................................................................... 10

5.3 Rated and limiting values ...................................................................................... 10

5.3.1 Rated voltage ................................................................................................ 10

5.3.2 Short-time withstand current .......................................................................... 10

5.3.3 Standard cross-sections ................................................................................ 10

5.3.4 Nominal cross-section ................................................................................... 11

5.3.5 Nominal connecting capacity ......................................................................... 11

5.3.6 Nominal current ............................................................................................. 11

6 Product information ....................................................................................................... 12

6.1 Marking ................................................................................................................. 12

6.2 Additional information ........................................................................................... 12

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 ....................................................................................................... 13

8.1.3 Clearances and creepage distances .............................................................. 13

8.1.4 Terminal identification and marking ............................................................... 14

8.1.5 Resistance to abnormal heat and fire ............................................................. 14

8.1.6 Nominal cross-section and nominal connection capacity ................................ 14

8.2 Performance requirements .................................................................................... 15

8.2.1 General ......................................................................................................... 15

8.2.2 Temperature-rise ........................................................................................... 16

8.2.3 Dielectric properties ....................................................................................... 16

8.2.4 Short-time withstand current .......................................................................... 17

8.2.5 Voltage drop .................................................................................................. 17

8.2.6 Electrical performance after ageing (for screwless-type terminal blocks

only) .............................................................................................................. 17

8.2.7 Current-cycle ageing test ............................................................................... 17

8.3 Electromagnetic compatibility ................................................................................ 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 terminal block on its support .............................................. 18

9.3.3 Mechanical properties of clamping units ........................................................ 20

9.4 Verification of electrical characteristics ................................................................. 21

---------------------- Page: 4 ----------------------
IEC TS 60947-7-5:2021 © IEC 2021 – 3 –

9.4.1 General ......................................................................................................... 21

9.4.2 Verification of clearances and creepage distances ......................................... 21

9.4.3 Dielectric tests ............................................................................................... 22

9.4.4 Verification of the voltage drop ...................................................................... 22

9.4.5 Temperature-rise test .................................................................................... 23

9.4.6 Short-time withstand current test ................................................................... 24

9.4.7 Ageing test (for screwless-type terminal blocks only) ..................................... 24

9.4.8 Current-cycle ageing test ............................................................................... 24

9.5 Verification of thermal characteristics ................................................................... 28

9.6 Verification of EMC characteristics ........................................................................ 30

9.6.1 Immunity ........................................................................................................ 30

9.6.2 Emission ........................................................................................................ 30

9.7 Items subject to agreement between manufacturer and user ................................. 30

Bibliography .......................................................................................................................... 31

Figure 1 – Arrangement for test according to 9.3.2 ............................................................... 19

Figure 2 – Arrangement for test according to 9.4.5 and for the verification of voltage drop .... 23

Figure 3 – Three-step test for AC/ DC ................................................................................... 25

Figure 4 – Arrangement for current-cycle ageing test according to 9.4.8 ............................... 26

Figure 5 – Schematic of conductor preparation (cross-section greater than 25 mm ) ............ 27

Figure 6 – Current-cycle ageing test procedure ..................................................................... 28

Figure 7 – Arrangement for test according to 9.5 .................................................................. 29

Figure 8 – Point of test flame contact .................................................................................... 30

Table 1 – Standard cross-section of conductors .................................................................... 11

Table 2 – Range for the nominal current for metric wire sizes ............................................... 15

Table 3 – Range for the nominal current for AWG or kcmil wire sizes ................................... 16

Table 4 – Attachment test parameters ................................................................................... 19

---------------------- Page: 5 ----------------------
– 4 – IEC TS 60947-7-5:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-5: Ancillary equipment –
Terminal blocks for aluminium 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

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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.

IEC TS 60947-7-5 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. It is a Technical Specification.

This publication shall be read in conjunction with the sixth edition of IEC 60947-1:2020 and the

third edition of IEC 60947-7-1:2009. The provisions of the general rules dealt with in

IEC 60947-1:2020 and the requirements for terminal blocks of IEC 60947-7-1:2009 are

applicable to this publication, where specifically called for. Clauses and subclauses, tables,

figures and annexes thus applicable are identified by reference to IEC 60947-1:2020 or

IEC 60947-7-1:2009.
---------------------- Page: 6 ----------------------
IEC TS 60947-7-5:2021 © IEC 2021 – 5 –
The text of this Technical Specification is based on the following documents:
Draft Report on voting
121A/418/DTS 121A/428A/RVDTS

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.

The language used for the development of this Technical Specification is English.

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.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/standardsdev/publications.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under 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 document 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.
---------------------- Page: 7 ----------------------
– 6 – IEC TS 60947-7-5:2021 © IEC 2021
INTRODUCTION

The connection of aluminium conductors, as defined in IEC 60228, and suitable terminations

for such conductors has been deemed relevant such that a specific test program for aluminium-

suited terminals and the development of a new publication under the scope of IEC SC121A are

appropriate.

Additional tests were deemed necessary due to experience showing that reliable electrical

connections for aluminium conductors require more consideration than those with copper mainly

due to different oxidative behaviour and mechanical characteristics of the materials.

It is well known that when two different metals come into contact; galvanic corrosion is likely to

occur. This is an electrochemical process where electrons will flow from the less noble metal to

the more noble metal. This effect will be sped up by additional DC current flow and the presence

of an electrolyte. In an electrical contact situation this process shall be considered, as it may

result in contamination of the contact area with corrosion products and reduction of contact

pressure and contact area when the termination is affected.

This document is based on the well-known test program for copper conductors as defined in

IEC 60947-7-1. However, further tests have been modified and added to those for copper

conductors. These additional tests were derived from those already defined in IEC 61545,

IEC 60269-2, IEC 60947-7-1 and IEC 60947-1.

There is a new current-cycling ageing test which includes pre-conditioning of the specimens by

storage in a cold environment followed by dry heat with AC for AC terminal blocks or damp heat

with DC for AC and/or DC terminal blocks, inspired by tests of Annex Q of IEC 60947-1:2020.

The current-cycling ageing test comprises a total of 768 on-off cycles. For testing the reference

value I is established from Table 2 becoming the base test current with an additional safety

margin of 1,25. The manufacturer is required to provide the I value to the user in his

documentation.

Therefore, in contrast to IEC 60947-7-1, it was necessary to introduce additional marking, which

is similar that of IEC 61545.
---------------------- Page: 8 ----------------------
IEC TS 60947-7-5:2021 © IEC 2021 – 7 –
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 7-5: Ancillary equipment –
Terminal blocks for aluminium conductors
1 Scope

This part of IEC 60947 specifies requirements for terminal blocks with screw-type or screwless-

type clamping units primarily intended for industrial or similar use and to be fixed to a support

to provide electrical and mechanical connection. This document can be used for terminal blocks

for connection between aluminium conductors or aluminium to copper conductors. It applies to

terminal blocks intended to connect round conductors, with or without special preparation,

2 2

having a cross-section between 2,5 mm and 300 mm (AWG 12 to 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 document can be used as a guide to qualify terminal blocks for conductors out of aluminium

not complying with IEC 60228 (e.g. smaller than 10 mm , flexible or other materials). This

document can also be used as a guide to qualify other types of terminal blocks for conductors

out of aluminium other than feed through terminal blocks (e.g. partially insulated terminal

blocks).
NOTE 1 AWG is the abbreviation of “American Wire Gage” (Gage (US) = Gauge (UK)).
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 does not apply to clamping units:
– dedicated to any other types of switchgear and controlgear;
– for connection by crimping, brazing, soldering or welding;
– for data and signalling circuits;

– for flat quick-connect terminations, insulation-piercing connecting devices and twist-on

connecting devices, for which separate parts are under consideration.

NOTE 2 In case of use of special types of conductors (e.g. cladded conductors) which require a special preparation,

this document can be used as a guide.

NOTE 3 In some countries, national regulation for installation rules can allow different cross-sections. For internal

wiring (inside enclosures), other rules or product standards can be applicable.

NOTE 4 For connections to copper conductors only, IEC 60947-7-1:2009 is applicable.

NOTE 5 In USA, UL 1059 applies and in Canada, CSA C22.2 No. 158 applies.

Where applicable in this document, the term “clamping unit” is used instead of the term

“terminal”. This is taken into account in case of reference to IEC 60947-1:2020.
---------------------- Page: 9 ----------------------
– 8 – IEC TS 60947-7-5:2021 © IEC 2021
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 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat

IEC 60068-2-78:2012, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady

state
IEC 60228, Conductors of insulated cables

IEC 60364-5-52:2009, Low-voltage electrical installations – Part 5-52: Selection and erection

of electrical equipment – Wiring systems

IEC 60695-11-5:2016, Fire hazard testing – Part 11-5: Test flames – Needle-flame test method

– Apparatus, confirmatory test arrangement and guidance
IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules

IEC 60947-7-1:2009, Low-voltage switchgear and controlgear – Part 7-1: Ancillary equipment

– Terminal blocks for copper conductors

ISO 4046-4:2016, Paper, board, pulps and related terms − Vocabulary – Part 4: Paper and

board grades and converted products
3 Terms and definitions
Clause 2 of IEC 60947-7-1:2009 applies with the following additions.
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
treated conductor

contact area of a conductor that has had its oxide layer on the outside strands scraped away

and/or has had a compound added to improve connectability and/or prevent corrosion

Note 1 to entry: In the USA and Canada, treatment of the specimens and conductors to be tested is not acceptable.

[SOURCE: IEC 61545:1996, 3.13, modified – Insertion of Note 1 to entry.]
3.2
prefilled clamping unit

clamping unit of a terminal block that is prefilled by the manufacturer with an

oxide-inhibiting compound
---------------------- Page: 10 ----------------------
IEC TS 60947-7-5:2021 © IEC 2021 – 9 –
3.3
nominal cross-section for aluminium conductors

value of cross-section for a given type of conductor, solid, rigid stranded or flexible, stated by

the manufacturer, and to which certain thermal, mechanical and electrical requirements are

referred

Note 1 to entry: Terminal blocks may have several nominal cross-sections depending on the type of conductor.

3.4
nominal connection capacity for aluminium conductors

range of cross-sections, types of conductors and, if applicable, the number of connectable

conductors, for which the terminal block is designed
3.5
corresponding copper conductors

cross-section value of the connectable types of conductors, rigid (solid and stranded) and

flexible, stated by the manufacturer, and to which certain thermal, mechanical and electrical

requirements are referred
3.6
nominal connection capacity for copper conductors

range of cross-sections and, if applicable, the number of connectable conductors, for which the

terminal block is designed
3.7
nominal current

current, as declared by the manufacturer, based

on the nominal cross-section of the aluminium conductors
4 Classification
Distinction is made between various type of terminal blocks as follows:
– method of fixing the terminal block to the support;
– number of poles;

– type of clamping units: screw-type clamping units or screwless-type clamping units;

– ability to receive different types of conductors, e.g, solid, rigid stranded or flexible

conductors;

– ability to receive different types of conductors based on their treatment; treated, untreated,

either treated or untreated;

– ability to receive either aluminium conductors or both aluminium and copper conductors;

– ability to receive prepared conductors (see 3.5.28 of IEC 60947-1:2020);
– terminal assemblies with identical or dissimilar clamping units;
– number of clamping units on each terminal assembly;
– service conditions;

– treatment of clamping units: filled (either prefilled or filled on site), unfilled;

– suitability for AC current and/or DC current.
---------------------- Page: 11 ----------------------
– 10 – IEC TS 60947-7-5:2021 © IEC 2021
5 Character
...

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