IEC 60981:2004

INTERNATIONAL IEC
STANDARD 60981
Second edition
2004-05
Extra-heavy duty electrical
rigid steel conduits
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INTERNATIONAL IEC
STANDARD 60981
Second edition
2004-05
Extra-heavy duty electrical
rigid steel conduits
 IEC 2004  Copyright - all rights reserved
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– 2 – 60981  IEC:2004(E)
CONTENTS
FOREWORD.3

1 Scope.5

2 Normative references.5

3 Terms and definitions .5

4 General requirements.6

4.1 Tests.6

4.2 Circular cross-section.6
4.3 Wall thickness.6
4.4 Surface condition.6
4.5 Welding.6
4.6 Cleaning.6
4.7 Protective coating.6
5 Dimensions.7
5.1 Dimensions.7
5.2 Threads.7
6 Zinc coating.7
7 Threading and chamfering .7
8 Couplings.8
8.1 General.8
8.2 Coupling threads.8
9 Elbows and nipples .8
10 Ductility.8
10.1 Bending properties.8
10.2 Ductility of zinc coating .8
11 Marking.9
11.1 General.9
11.2 Required information.9

Annex A (normative) Test for thickness of zinc coating on extra heavy-duty electrical
rigid steel (EHDERS) conduits.15

Figure 1 – Dimensions of threads for EHDERS conduit.11
Figure 2 – Basic form of taper thread .12
Figure 3 – Limits on crest and root truncation of external and internal threads .13
Figure 4 – Dimensions of a ferrous metal coupling.14

Table 1 – Dimensions and mass of EHDERS conduit.9
Table 2 – Dimensions of couplings .10
Table 3 – Dimensions of 90° elbows .10

60981  IEC:2004(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
EXTRA HEAVY-DUTY ELECTRICAL RIGID STEEL CONDUITS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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International Standard IEC 60981 has been prepared by subcommittee 23A: Cable
management systems, of IEC technical committee 23: Electrical accessories.

This second edition cancels and replaces the first edition published in 1989. This edition
constitutes a technical revision. It incorporates two main changes to the first edition, including:
– the addition of provisions for alternative coatings to zinc, and
– revisions to ductility requirements.
The text of this standard is based on the following documents:
FDIS Report on voting
23A/443/FDIS 23A/445/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 60981  IEC:2004(E)
The committee has decided that the contents of this publication will remain unchanged until
2007. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or

• amended.
A bilingual version of this publication may be issued at a later date.

60981  IEC:2004(E) – 5 –
EXTRA HEAVY-DUTY ELECTRICAL RIGID STEEL CONDUITS

1 Scope
This International Standard specifies requirements for EHDERS (extra heavy-duty electrical

rigid steel) conduits, couplings, nipples and elbows for electrical installations, including

communications and fibre optics. This standard also specifies threads for these components.

It is not applicable to the conduits specified in IEC 60423.

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 61950, Cable management systems – Specification for conduit fittings for electrical
installations for extra-heavy duty metal conduit
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
extra heavy-duty electrical rigid steel conduit (EHDERS)
part of a closed wiring system of circular cross-section made of welded steel construction
capable of providing extra heavy mechanical protection to conductors or cables in electrical
installations and used as an equipment earthing conductor when installed utilizing appropriate
fittings
3.2
straight conduit
straight length of EHDERS without a coupling
3.3
finished conduit
straight length of EHDERS with one coupling attached

3.4
threaded coupling
internally threaded steel cylinder for connecting two sections of EHDERS conduit.
3.5
elbow
curved section of EHDERS conduit threaded at each end
3.6
nipple
straight section of EHDERS conduit not more than 0,6 m long and threaded at each end
3.7
type test
test made on a specimen for the conformity of the design of a given product to the
requirements of the relevant standard

– 6 – 60981  IEC:2004(E)
4 General requirements
4.1 Tests
Tests according to this standard shall be type tests.

Unless otherwise specified, the tests shall be carried out at an ambient temperature of

(20 ± 5) °C.
Unless otherwise specified, each test shall be carried out on two new samples. If a sample

tested in accordance with this standard fails, two additional samples shall be tested, both of

which shall comply with all the requirements of this standard.
4.2 Circular cross-section
An EHDERS conduit shall have a circular cross-section sufficiently accurate to permit the
cutting of threads in accordance with Figure 1.
4.3 Wall thickness
The wall thickne
...