BRITISH STANDARD

BS EN
50290-2-24:
2002+A1:2008
Incorporating
corrigendum
January 2011

Communication
cables —
Part 2-24: Common design rules and
construction — PE sheathing

ICS 29.035.20; 33.120.01

NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW


BS EN 50290-2-24:2002+A1:2008

National foreword
This British Standard is the UK implementation of
EN 50290-2-24:2002+A1:2008. It supersedes BS EN 50290-2-24:2002 which
is withdrawn.
The start and finish of text introduced or altered by amendment is indicated in
the text by tags. Tags indicating changes to CENELEC text carry the number
of the CENELEC amendment. For example, text altered by CENELEC
amendment A1 is indicated by !".
The UK participation in its preparation was entrusted by Technical Committee
EPL/46, Cables, wires and waveguides, RF connectors and accessories for

communication and signalling, to Subcommittee EPL/46/1, Communication
cables.
A list of organizations represented on this subcommittee can be obtained on
request to its secretary.
This publication does not purport to include all the necessary provisions of a
contract. Users are responsible for its correct application.
Compliance with a British Standard cannot confer immunity from
legal obligations.

This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee on
15 April 2002

Amendments /corrigenda issued since publication

© BSI 2011

ISBN 978 0 580 74255 2

Date

Comments

30 April 2009

Implementation of CENELEC amendment A1:2008

31 January 2011


Correction to identifier on EN title page


EUROPEAN STANDARD

EN 50290-2-24:2002+A1

NORME EUROPÉENNE
EUROPÄISCHE NORM

October 2008

ICS 29.035.20; 33.120.10

Supersedes HD 624.4 S1:1996

English version

Communication cables
Part 2-24: Common design rules and construction –
PE sheathing
Câbles de communication
Partie 2-24: Règles de conception
communes et construction –
Polyéthylène pour gainage

Kommunikationskabel
Teil 2-24: Gemeinsame Regeln
für Entwicklung und Konstruktion –

PE-Mantelmischungen

This European Standard was approved by CENELEC on 2001-11-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any
other language made by translation under the responsibility of a CENELEC member into its own
language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC -

All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50290-2-24:2002 E


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-2-


Foreword
This European Standard was prepared by a joint working group of the Technical Committees CENELEC
TC 46X, Communication cables, and CENELEC TC 86A, Optical fibres and optical fibre cables.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC
as EN 50290-2-24 on 2001-11-01.
This European Standard supersedes HD 624.4 S1:1996.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement

(dop)

2002-08-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn

(dow)

2004-08-01

Annexes designated "normative" are part of the body of the standard.
In this standard, annexes A, B and C are normative.
This European Standard has been prepared under the European Mandate M/212 given to CENELEC by the
European Commission and the European Free Trade Association.
_________

Foreword to amendment A1
This amendment was prepared by a Joint Working Group of the Technical Committees CENELEC TC 46X,

Communication cables, and CENELEC TC 86A, Optical fibres and optical fibre cables.
The text of the draft was submitted to the Unique Acceptance Procedure and was approved by CENELEC as
amendment A1 to EN 50290-2-24:2002 on 2008-11-01.
The purpose of this amendment is to align EN 50290-2-24:2002 with new grades available.
The following dates were fixed:
–

–

latest date by which the amendment has to be implemented
at national level by publication of an identical
standard or by endorsement

(dop)

2009-11-01

latest date by which the national standards conflicting
with the amendment have to be withdrawn

(dow)

2011-11-01

__________


-3-

1


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

Scope

This Part 2-24 of EN 50290 gives specific requirements for PE sheathing compounds used in
communication cables.
It is to be read in conjunction with Part 2-20 of EN 50290.
2

Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply
to this European Standard only when incorporated in it by amendment or revision. For undated references
the latest edition of the publication referred to applies (including amendments).
EN 60811-1-1:1995

Insulating and sheathing materials of electric and optical cables - Common
test methods -- Part 1-1: General application - Measurement of thickness and
overall dimensions - Tests for determining the mechanical properties
(IEC 60811-1-1:1993)

EN 60811-1-2:1995

Insulating and sheathing materials of electric cables - Common test methods
Part 1-2: General application -- Thermal ageing methods
(IEC 60811-1-2:1985 + corr. May 1986 + A1:1989)


EN 60811-1-3:1995

Insulating and sheathing materials of electric and optical cables - Common
test methods -- Part 1-3: General application - Methods for determining the
density - Water absorption tests - Shrinkage test (IEC 60811-1-3:1993)

EN 60811-1-4:1995

Insulating and sheathing materials of electric and optical cables - Common
test methods -- Part 1-4: General application - Tests at low temperature
(IEC 60811-1-4:1985 + corr. May 1986 + A1:1993)

EN 60811-4-1:1995

Insulating and sheathing materials of electric cables - Common test methods
- - Part 4: Methods specific to polyethylene and polypropylene compounds - Section 1: Resistance to environmental stress cracking - Wrapping test after
thermal ageing in air - Measurement of the melt flow index - Carbon black
and/or mineral content measurement in PE (IEC 60811-4-1:1985)

EN 60811-4-2:1999

Insulating and sheathing materials of electric and optical fibre cables Common test methods - - Part 4: Methods specific to polyethylene and
polypropylene compounds Section 2: Tensile strength and elongation at break
after pre-conditioning - Wrapping test after thermal ageing in air Measurement of mass increase – Long - term stability test - Test method for
copper - catalysed oxidative degradation
(IEC 60811-4-2:1990, mod.)

3


Requirements

In case of specific applications, additional performances could be needed. Relevant test methods and
requirements shall be included in the detail specifications of the cables.


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-4-

Table 1 – Black PE sheathing compound

!
Characteristics

Test method

a

Unit

Grades
(see Note 1)
LD

MD

HD


LLD

°C

70

80

80

80

EN 60811-1-3,
Clause 8

g/cm³

< 0,930

≥ 0,930
≤ 0,940

> 0,940

< 0,930

EN 60811-4-1,
Clause 10

g/10 min


≤ 0,4

≤ 2,0

≤ 2,0

≤ 3,0

1

Maximum rated temperature
at cable for which the
compound can be used

2

Density
(without carbon black)

3

Melt flow index
(see Note 2)

4

Mechanical characteristics

4.1


In state of delivery
Tensile strength
– median, min.

MPa

10

18

18

16

Elongation at break
– median, min.

%

300

300

300

500

°C


100 ± 2

100 ± 2

100 ± 2

100 ± 2

h

24 x 10

24 x 10

24 x 10

24 x 10

%

300

300

300

500

mm


200

200

200

200

°C

c

c

c

c

h

c

c

c

c

%


c

c

c

c

4.2

a

a

After ageing

EN 60811-1-1,
9.2

EN 60811-1-2,
8.1

Ageing conditions
– temperature
– duration
Elongation at break
– median, min.
5

Shrinkage


b

EN 60811-1-3,
Clause 11

Test conditions
– sample length
(if not otherwise specified)

– temperature
– duration
Result to be obtained
– shrinkage, max.

"


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-5-

Table 1 – Black PE sheathing compound (continued)

!
Characteristics

Test method


a

Unit

Grades
(see Note 1)
LD

6

Performance after
pre-conditioning
(for sheath in direct contact
with filling compound)

°C

– duration
Result to be obtained
Tensile strength
– median, min.
Elongation at break
– median, min.
d

Carbon black content

8

Carbon black dispersion


9

Stress cracking
(see Note 3)

EN 60811-4-1,
Clause 11
d

d

HD

LLD

Annex A

Test conditions
– temperature

7

MD

Annex B
EN 60811-4-1,
Clause 8,
Procedure B


60/70 ± 2 60/70 ± 2 60/70 ± 2 60/70 ± 2

h

7 x 24

7 x 24

7 x 24

7 x 24

MPa

10

18

18

16

%

300

300

300


500

%

2,5 ± 0,5

2,5 ± 0,5

2,5 ± 0,5

2,5 ± 0,5

To meet

To meet

To meet

To meet

> 1 000 h > 1 000 h > 1 000 h > 1 000 h

NOTE 1 In order to differentiate LD from LLD-Polyethylene the melting point according to ISO 11357-3 e can be measured. The
melting point of LD is < 120 °C and of LLD is ≥ 120 °C.
NOTE 2 If required, MFI may be measured on sheath with other values to be specified.
NOTE 3 Stress cracking test on raw material may not be sufficient to guarantee a stress cracking performance on finished product.
Therefore an additional test has to be performed either on complete cable or on a piece of sheath taken from complete cable, in
accordance with the test methods described in Annex C.
a


To be given by the supplier.

b

For special application.

c

In the relevant cable specification.

d

For inner sheath applications, non-black PE compounds can be used, then items 7, 8, 9 may not apply.

e

ISO 11357-3, Plastics – Differential scanning calorimetry (DSC) – Part 3: Determination of temperature and enthalpy of melting and
crystallization

"


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-6-

Table 2 – Coloured PE sheathing compounds

!

Characteristics

1

Maximum rated temperature
at cable for which the
compound can be used

2

Density

3

Melt flow index
(see Note 2)

4

Mechanical characteristics

4.1

In state of delivery
Tensile strength
– median, min.

a

a


Test method

After ageing

MD

HD

LLD

°C

70

80

80

80

EN 60811-1-3,
Clause 8

g/cm³

< 0,930

≥ 0,930
≤ 0,940


> 0,940

< 0,930

EN 60811-4-1,
Clause 10

g/10 min

≤ 0,4

≤ 2,0

≤ 2,0

≤ 3,0

MPa

10

18

18

16

%


300

300

300

500

°C

100 ± 2

100 ± 2

100 ± 2

100 ± 2

h

24 x 10

24 x 10

24 x 10

24 x 10

%


300

300

300

500

mm

200

200

200

200

°C

c

c

c

c

h


c

c

c

c

%

c

c

c

c

EN 60811-1-1,
9.2

EN 60811-1-2,
8.1

Ageing conditions
– temperature
– duration
Elongation at break
– median, min.
5


Shrinkage

b

Grades
(see Note 1)
LD

Elongation at break
– median, min.
4.2

a

Unit

EN 60811-1-3,
Clause 11

Test conditions
– sample length
(if not otherwise specified)

– temperature
– duration
Result to be obtained
– shrinkage, max.

"



BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-7-

Table 2 – Coloured PE sheathing compounds (continued)

!

Characteristics

Test method

a

Unit

Grades
(see Note 1)
LD

6

Performance after
pre-conditioning
(for sheath in direct contact
with filling compound)


°C

– duration
Result to be obtained
Tensile strength
– median, min.
Elongation at break
– median, min.
Stress cracking
(see Note 3)

HD

LLD

Annex A

Test conditions
– temperature

7

MD

EN 60811-4-1,
Clause 8,
Procedure B

60/70 ± 2 60/70 ± 2 60/70 ± 2 60/70 ± 2


h

7 x 24

7 x 24

7 x 24

7 x 24

MPa

10

18

18

16

%

300

300

300

500


> 1 000 h > 1 000 h > 1 000 h > 1 000 h

NOTE 1 In order to differentiate LD from LLD-Polyethylene the melting point according to ISO 11357-3 d can be measured. The
melting point of LD is < 120 °C and of LLD is ≥ 120 °C.
NOTE 2 If required, MFI may be measured on sheath with other values to be specified.
NOTE 3 Stress cracking test on raw material may not be sufficient to guarantee a stress cracking performance on finished product.
Therefore an additional test has to be performed either on complete cable or on a piece of sheath taken from complete cable, in
accordance with the test methods described in Annex C.
a

To be given by the supplier.

b

For special application.

c

In the relevant cable specification.

d

ISO 11357-3, Plastics – Differential scanning calorimetry (DSC) – Part 3: Determination of temperature and enthalpy of melting and
crystallization

Guidance to use:
Natural or coloured polyolefin cable sheaths, containing conventional antioxidant stabilisers degrade rapidly
when subjected to natural daylight weathering through photocatalysed oxidation (actinic degradation).
Degradation is manifested by discolouration of the sheath followed immediately by loss of mechanical
properties and spontaneous cracking.

This ageing process is accelerated in situations where the sheath is physically stressed, for example at
sharp bends. Under temperate European climates failure can occur within two years of exposure. Ageing
will not only occur on installed cables but also on cables stored externally on drums or reels where the
cables have been inadequately protected from solar radiation.
Ultraviolet stabilisation systems may be incorporated in the sheath compound to extend the induction period
before the onset of failure. Such systems will permit prolonged external storage of cables but their
performance does not approach that of conventional sheaths containing a minimum of 2 % of carbon black.
Consequently they are unsuitable for external use where long service lives are required, especially where
the cable will be installed in exacting climatic conditions such as aerial cables

"


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

-8-

Annex A
(normative)
Performances after pre-conditioning
To perform the test, use EN 60811-4-2 with the following modifications1:
1 Scope - Second paragraph
Replace "...elongation at break..." by "...tensile strength and elongation at break...".
6 Pre-conditioning
Replace the existing title by the following new title:
6 Conditioning
8 Elongation at break after pre-conditioning
Replace the existing title and text of this clause by the following new title and text:
8 Tensile strength and elongation at break after pre-conditioning

8.1 General
This text is intended for filled cables for polyolefin insulations with a wall thickness of more than 0,8 mm and
for polyolefin sheaths in direct contact with filling compound.
8.2 Pre-conditioning procedure
A sample of complete cable of sufficient length shall be pre-conditioned in air (i.e. suspended in an oven).
The duration of the test and the temperature of the air maintained continuously shall be as follows:
-

7 x 24 h at 60 °C for filling compound having a nominal drop-point above 50 °C and up to an including
70 °C.

-

7 x 24 h at 70 °C for filling compound having a nominal drop-point above 70 °C.

After pre-conditioning, the cable sample shall be left at ambient temperature for at least 16 h without being
exposed to direct sunlight. Then the sheath and cores to be tested shall be taken from the cable and shall
be cleaned by suitable means.
8.3 Tensile strength and elongation tests after pre-conditioning
Tensile strength and/or elongation tests, with respect to requirements in the cable standard, on test pieces
according to 8.2 shall be performed in accordance with clause 9 of EN 60811-1-1 without any further ageing
treatment.

1)

The modifications listed are intended for revision of EN 60811-4-2 (IEC 60811-4-2).


-9-


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

9 Wrapping test after pre-conditioning
9.2 Test procedure
Replace the existing title and text of the subclause by the following new title and text:
9.2 Pre-conditoning procedure
The pre-conditiong shall be carried out in accordance with 8.2 of this standard. Then the cores to be tested
shall be taken from the cable and shall be cleaned by suitable means.
9.3 Evaluation of results
Replace the existing title and text of the subclause by the following new title and text:
9.3 Test procedure
Test pieces according to 9.2 shall be subjected to a winding test in accordance with the method specified in
10.5.2.
For cellular insulations including foam-skin having a wall thickness below or equal to 0,2 mm the pull
exerted on the exposed conductor shall be reduced to about 7,5 N/mm 2 with respect to the conductor crosssection.
Add a new subclause:
9.4 Evaluation of results
After cooling down to ambient temperature, the test pieces shall show no cracks when examined with
normal or corrected vision without magnification. The test may be repeated once only if one test piece fails.
10.5 Test procedure
Replace the existing text by the following new text, inserting two subclauses:
10.5.1 Test pieces according to 10.3 shall be subjected, after ageing in accordance with 10.4, to a winding
test at ambient temperature.
10.5.2 The conductor shall be laid bare at one end. A weight shall be applied to the exposed conductor end,
exerting a pull of about 15 N/mm 2 ± 20 % with respect to the conductor cross-section. Ten windings shall be
made on the other end of the test piece by means of a winding device in accordance with 10.2.2 on a metal
mandrel at a speed of about one revolution per 5 s. The winding diameter shall be 1 to 1,5 times the test
piece diameter. Subsequently, the test pieces wound on the mandrel shall be removed from the latter and
shall be kept in their helical form for 24 h at 70 ± 2 °C in the vertical position, substantially in the middle of

the heating chamber in accordance with 10.2.3.


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 10 -

Annex B
(normative) 2)
Test methods for the assessment of carbon black dispersion in
polyethylene using a microscope

B.1 Introduction
The methods below describe procedures for assessing the uniformity of dispersion of carbon black in a
compound or extrusion.

B.2 Scope
These methods describe procedures for assessing the carbon black dispersion in polyethylene using a
microscope.
Procedure A is primarily intended for use with polyethylene compounds but may be used for extrusions.
Procedure B is intended for use with polyethylene extrusions or moundings only.

B.3 Principle
Procedure A
A small sample of the material is squeezed into a thin layer 20 mm to 30 mm thick between two microscope
slides heated to either 170 °C to 210 °C, or a higher temperature if specified in the material specification.
The pressed sample is examined microscopically by transmitted light. The frequency and size distribution of
particles and agglomerates is measured and graded by comparison with Table B.1.
The uniformity of dispersion is assessed by comparison with the photomicrographs of Table B.2.

Procedure B
A microtome section of the material, 10 mm to 20 mm thick, is examined as per procedure A.

B.4 Apparatus
The following apparatus is required.

B.4.1 Hot plate
Capable of being controlled at the required temperature.

B.4.2 Microscope slides
B.4.3 Microscope
Calibrated and capable of at least X 200 magnification. The circular field of view at X 100 magnification
shall be 0,7 mm ± 0,07 mm.

2)

Based on ISO document at draft stage, as ISO/DIS 18553.


- 11 -

BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

B.4.4 Microtome
B.5 Procedure
B.5.1 Preparation of specimens
Procedure A
Place two of the clean microscope slides on the hotplate maintained at 170 °C to 210 °C, or other higher
temperature, as specified in the material specification. Choose six separate granules of compound, or six

separate parts of an extruded article, to be as representative as possible of the whole batch. Cut a specimen
of approximate mass 0,2 mg from the interior of each granule or part. Place the six specimens on one of the
hot microscope slides so that each one is approximately equidistant from its neighbour(s) and from adjacent
edge(s) of the slide.
Place the second slide over the first, and press the specimens out by applying even pressure for 1 minute to
2 minutes to the whole area of the face of the upper slide. Exert an amount of pressure for a period
necessary for each specimen to be pressed out to a thickness of between 20 mm and 30 mm.
After the specimens have been placed on the slide, the latter shall in no case remain on the hotplate for
more than 3 minutes.
Remove the slide from the hotplate and allow it to cool.
NOTE

Shims of metal or some other suitable material may be used to achieve the required specimen thickness and uniformity of thickness.

Procedure B
Cut six microtome sections of thickness between 10 mm and 20 mm each approximately of mass 0,25 mg,
from different parts of the extrusion or moulding.

B.5.2 Assessment of dispersion
Agglomerates
Examine the six specimens in turn under the microscope under transmitted light with a magnification of at
least X 100.
For each specimen examine the agglomerates checking that they are really pigment by varying the light
intensity and using transmitted and reflected light if possible. Measure and record the largest dimension of
each agglomerate, ignoring those less than 5 mm. Rate according to the size categories given in Table B.1.
Examine the whole of the specimen.
NOTE If larger sample sizes are used to prepare the specimens the number of for a 1,25 mg sample mass.

For some pigments no particles or agglomerates greater than 5 mm may be visible, hence a grading of 0 is
obtained from Table B.1.

Appearance
Examine each of the specimens in turn under the microscope under transmitted light at a magnification
X 100 ± 10.
Compare each specimen with the micrographs in the Table B.2 for uniformity of appearance taking into
account smears and streaks.


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 12 -

B.6 Expression of results
B.6.1 Grading of agglomerates
Using Table B.1, determine the highest grade for each sample. Calculate the arithmetic mean of the six
gradings obtained, and express the result to a single decimal point, rounded up to its higher value (see the
examples given in Table B.3).

B.6.2 Rating of appearance
Express the appearance as the highest comparative rating with the photomicrographs in Table B.2.

B.7 Requirements
The mean agglomerate grading shall not be greater than 4,0.
The appearance rating shall not be worse than photomicrograph C2.


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 13 Table B.1 (normative) - Grading table for agglomerates

Dimensions
(m)

5
to

11

21

31

41

51

61

71

81

91

101

111

121


131

141

10

20

30

40

50

60

70

80

90

100

110

120

130


140

150

Grades
0

0

0,5

1

1

£3

+

1

1,5

£6

+

£3

+


1

2

£ 12

+

£6

+

£3

+

1

2,5

> 12

+

£ 12

+

£6


+

£3

+

1

> 12

+

£ 12

+

£6

+

£3

+

1

> 12

+


£ 12

+

£6

+

£3

+

1

> 12

+

£ 12

+

£6

+

£3

+


1

> 12

+

£ 12

+

£6

+

£3

+

1

> 12

+

£ 12

+

£6


+

£3

+

1

< 12

+

£ 12

+

£6

+

£3

+

1

> 12

+


£ 12

+

£6

+

£3

+

1

> 12

+

£ 12

+

£6

+

£3

+


1

> 12

+

£ 12

+

£6

+

£3

3
3,5
4
4,5
5
5,5
6
6,5
7

0
0
0

0
0
0
0
0
0

NOTE 7 mm corresponds to 0,7 spc mm under a magnification of 100; similarly 60 mm corresponds to 6 spc mm under a magnification of 100.

0
0
0
0
+

1

0


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 14 -

Table B.2 (normative) - Photomicrographs for rating the appearance of dispersions


- 15 -


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 16 -

Table B.3 (informative) - Examples of grading of agglomerates
Table B.3.1 - Example 1
Dimension samples
(mm)

5
to
10

11

21

31

41

51

61


Sample 1

Sample 2

20

30

40

50

60

70

3

2

1

Grade 2,0

3

5

1


Grade 2,5

2

1

Grade 3,0

Sample 3

14

Grading for the sample

Sample 4

3

2

2

Grade 2,5

Sample 5

3

2


4

Grade 3,0

Sample 6

3

5

7

Grade 3,5

12

Incidence of agglomerates by size
Table B.3.1 shows the number of agglomerates, classed by size, in each sample.
Gradings:
(2,0 + 2,5 + 3,0 + 2,5 + 3,0 + 3,5) / 6 = 2,75
Hence the mean grade = 2,8


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 17 -

Table B.3 (informative) - Examples of grading of agglomerates (Cont’d)
Table B.3.2 - Example 2

Dimension samples
(mm)

5
to
10

11

21

31

41

51

20

30

40

50

60

Sample 1

7


3

9

3

Sample 2

7

3

9

3

Grade 3,0

Sample 3

7

3

5

3

Grade 2,5


Sample 4

19

5

1

Grade 2,5

Sample 5

19

5

Sample 6

1

2

1

Table B.3.2 shows the number of agglomerates, classed by size, in each sample.

(3,0 + 3,0 + 2,5 + 2,5 + 3,0 + 3,0) / 6 = 2,8333
Hence the mean grading = 2,9


Grade 3,0

Grade 3,0

Incidence of agglomerates by size

Gradings:

Grading of the sample

Grade 3,0


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 18 -

Annex C
(normative)
Resistance to environmental stress cracking on cable sheath

C.1 Purpose
The purpose of this annex is to describe methods to evaluate the resistance to stress cracking of the
polyethylene cable jackets.
C.2 Method A - Test on complete cable
C.2.1 General
This test method is applicable for all sizes of cable.
A test specimen comprising a length of cable is submitted both to a constant deformation and to a surfaceactive liquid heated at 50 °C.
C.2.2 Apparatus

C.2.2.1 Metallic half-circular bends whose diameter is 12 times the cable diameter.
C.2.2.2 A climatic circulating air oven whose dimensions are sufficient to accept bends with test specimens
to be tested. The temperature shall be regulated (70 ± 1) °C.
C.2.2.3 Surface-active liquid whose volume is sufficient and regulated (50 ± 1) °C.
The surface-active liquid used is an aqueous solution containing 1 % of polyethanol-nonyl-phenol (Igepal
CO-630 or Antarox CO-630 or equivalent).
This reagent is bio-degradable, the bath shall be regenerated after a maximum 10 days of use.
C.2.3 Specimen
Test specimens shall constitute cable lengths whose dimensions comply with the relevant bend diameter.
These specimens shall form a semi-circle and shall be secured on the mandrel with metallic clamps or
polyamide bonds, located at the end of the bend.
A minimum length of one metre, for each cable, consisting of one or several specimens, shall be tested.
C.2.4 Procedure
C.2.4.1 The bent cable on the mandrel is placed in the climatic oven for 4 hours; at a temperature of
(70 ± 2) °C.
C.2.4.2 The cable and the mandrel are then removed from the oven and kept at ambient temperature for a
minimum duration of 4 hours.
C.2.4.3 The specimen is removed from the mandrel, straightened and then bent in the reverse direction on
the same mandrel.
C.2.4.4 The specimen and the mandrel are then immersed in the bath of surface-actve liquid, heated to
(50 ± 2) °C for 72 hours.


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BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

C.2.5 Evaluation of results
Examination for presence of cracks, with normal or corrected vision without magnification.

C.2.6 Test report
The test report shall mention
- the type of cable;
- the cable diameter;
- the diameter of the bend used;
- the number of specimens tested and their length;
- any other observations;
- the result obtained.
C.3 method B - Test on pieces of sheath
C.3.1 General
This method can be used for cable diameter greater than 10 mm and sheath thickness greater than 1,6 mm.
C.3.2 Apparatus
C.3.2.1 An apparatus to achieve test pieces with two smooth and parallel surfaces by cutting.
C.3.2.2 Electrically heated air oven
C.3.2.3 Clean, sharp, undamaged blanking die with blanking press suitable for cutting test pieces
(38,0 ± 2,5) mm x (13,0 ± 0,8) mm or other suitable devices.
In case of sheath thickness greater than 2,0 mm the sample thickness must be reduced by suitable means
to the value specified in C.3.3.
C.3.2.4 Dial gauge, with spherical measuring inset (ball-diameter: at least 3 mm) pressure of 0,3 N to
1,5 N.
C.3.2.5 Notching device as in Figure C.1 with blades as in Figure C.2.
C.3.2.6 Bending clamp assembly as in Figure C.3 with vice or other suitable device ensuring the
symmetrical closing of the clamping jaws.
C.3.2.7 Transfer tool assembly as in Figure C.4 for shifting in one operation the bent test piece(s) from the
bending clamp to the brass channel.
C.3.2.8 Brass channel specimen holder as in Figure C.5 for accommodating ten bent test pieces.
C.3.2.9 Hard glass test tubes 200 mm x 32 mm for accommodating the brass channel specimen holder with
the bent test specimens. The tubes are plugged by suitable aluminium foil wrapped corks (see Figure C.6).
C.3.2.10 Reagent: 10 % aqueous solution of Igepal CO-630 or Antarox CO-630 or equivalent reagent.
The reagent shall be used only once.

C.3.2.11 A heated container of sufficient size and depth to accept racks which will hold the filled test tubes
(Figure C.6). The temperature shall be maintained at (50 ± 0,5) °C by means of suitable equipment. The
thermal capacity shall be high enough to ensure that the temperature does not drop below 49 °C even when
the test tubes are inserted.


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 20 -

C.3.3 Samples
Examination of the PE cable sheaths. The surfaces shall not show any swellings, dents or holes.
The apparatus as in C.3.2.1 is used to prepare strips with two parallel surfaces from the cable sheath. The
samples should be taken in direction of the cable axis and approximately in the middle of the test piece,
with a thickness of 1,8 mm, and from these strips 10 test pieces are prepared as in C.3.2.3. The thickness of
these test pieces, measured using the dial gauge as in C.3.2.4, shall be (1,8 ± 0,2) mm.
The surfaces of the test pieces shall be at right angles to each other, as oblique edges can lead to
erroneous results. The test pieces are kept in a straight condition for at least 16 hours in the oven as in
C.3.2.2 at a temperature of (70 ± 2) °C and then cooled to room temperature.
C.3.4 Procedure
Shortly before placing into the reagent, each of the test pieces shall be given a notch in the middle of the
test piece surface (Figure C.7) using the notching devices as in C.3.2.5.
The notch depth shall be 0,30 mm to 0,40 mm.
NOTE The blade shall be neither dull nor damaged and, therefore, shall be replaced as required. Even under favourable conditions it should
not be used for more than 100 notches.

Ten test pieces are then placed , with the notch up, in the bending clamp as in C.3.2.6. The clamp is closed
for 30 s to 35 s by means of a vice or a motor-driven arbor press at a constant speed.
The bent test pieces are lifted with the transfer tool as in C.3.2.7 from the bending clamp and placed in the

brass channel as in C.3.2.8. If some test pieces are riding too high in the holder they shall be forced down
by manual pressure.
The holder is inserted in a tube as in C.3.2.9, 5 min to 10 min after the test pieces have been bent. The test
tube is filled with the appropriate reagent as in C.3.2.10 until all the test pieces are covered by the liquid,
and shall be closed by a cork.
The filled test tube shall be placed immediately in a rack in the heated container as in C.3.2.11. Care shall
be taken that the test pieces do not touch the test tube during the test. The moment of insertion in the
heated container shall be noted.
The holder with the test tubes and the test pieces shall be maintained for 48 hours in the heated container at
(50 ± 2) °C.
C.3.5 Evaluation of results
After removal from the heated container, the 10 test pieces are examined for cracks with normal or
corrected vision without magnification.
The test is considered as passed when none of ten test pieces shows a crack.
If only one test piece fails, the test shall be repeated with 10 new test pieces from the cable sheath. Then
only the test pieces of the repeated test will be considered. The test is considered as passed if no test piece
fails.
NOTE In general the stress cracks originate perpendiculary from the notch.


- 21 -

The blade is made of “Gem” as in Figure C.2

Insert test specimen
Front clamp

Rear clamp

Guide bar


Screw

BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008


BS EN 50290-2-24:2002+A1:2008
EN 50290-2-24:2002+A1:2008

- 22 -

Channel internal width
dimension

Test tube with inserted brass channel specimen holder
containing ten test specimens


blank