EN 50525-3-21:2011

Electric cables - Low voltage energy cables of rated voltages up to and including 450/750 V (U0/U) - Part 3-21: Cables with special fire performance - Flexible cables with halogen-free crosslinked insulation, and low emission of smoke

EN 50525-3-21 applies to flexible cables, insulated and sheathed with halogen-free crosslinked compound and having low emission of smoke and corrosive gases when exposed to fire. NOTE 1 Low emission of smoke is checked in accordance with EN 61034-2. Low emission of corrosive gases is checked as part of the check for absence of halogens (see Annex B of EN 50525-1). The cables are of rated voltage U0/U 450/750 V. The cables are intended for the connection of equipment and machinery to the fixed supply. The maximum conductor operating temperature for each of the cables in this standard is 90 °C. NOTE 2 HD 516 contains extensive guidance on the safe use of cables in this standard. This EN 50525-3-21 should be read in conjunction with EN 50525-1, which specifies general requirements.

Kabel und Leitungen - Starkstromleitungen mit Nennspannungen bis 450/750 V (U0/U) - Teil 3-21: Starkstromleitungen mit verbessertem Verhalten im Brandfall - Flexible halogenfreie, raucharme Leitungen mit vernetzter Isolierung

Câbles électriques - Câbles d’énergie basse tension de tension assignée au plus égale à 450/750 V (U0/U) - Partie 3-21: Câbles à performances spéciales au feu - Câbles souples isolés en matériau élastomère réticulé sans halogène, à faible dégagement de fumée

Električni kabli - Nizkonapetostni energetski kabli z naznačeno napetostjo do vključno 450/750 V (U0/U) - 3-21. del: Kabli s posebnimi ognjevarnimi lastnostmi - Zvijavi kabli z zamreženo izolacijo brez halogenov in z nizko emisijo dima

EN 50525-3-21 velja za zvijave kable, ki so oplaščeni in imajo zamreženo izolacijo brez halogenov ter nizko emisijo dima in korozivnih plinov pri izpostavljenosti ognju. Nizka emisija korozivnih plinov se preverja kot del kontrole, da ni prisotnih halogenov. Ti kabli imajo nazivno napetost U0/U do vključno 450/750 V. Povezujejo opremo in stroje s fiksnim napajanjem. Maksimalna delovna temperatura pretvornika za vsakega od kablov iz tega standarda je 90 °C.

General Information

• Status: Published
• Publication Date: 05-May-2011
• Withdrawal Date: 16-Jan-2014
• ICS: 29.060.20 - Cables
• Technical Committee: CLC/TC 20 - Electric cables
• Drafting Committee: CLC/TC 20 - Electric cables
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 23-Oct-2024
• Completion Date: 20-Feb-2026
• Directive: Not Harmonized2006/95/EC - Directive 2006/95/EC of the European Parliament and of the Council of 12 December 2006 on the harmonisation of the laws of Member States relating to electrical equipment designed for use within certain voltage limits (codified version)
  OJ Ref: C 256/01, C 348/03 OJ Date: 28-Nov-2013
• Directive:

  ---

  Harmonized Standard2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
  OJ Ref: C 249/03 OJ Date: 08-Jul-2016
• Directive:

  ---

  Harmonized Standard2014/53/EU - Directive 2014/53/EU of The European Parliament and of the Council of 16 April 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of radio equipment and repealing Directive 1999/5/EC
• Ref Project: SIST EN 50525-3-21:2011 - Electric cables - Low voltage energy cables of rated voltages up to and including 450/750 V (U0/U) - Part 3-21: Cables with special fire performance - Flexible cables with halogen-free crosslinked insulation, and low emission of smoke

Relations

• Replaces: HD 22.13 S2:2007 - Cables of rated voltages up to and including 450/750 V and having cross-linked insulation - Part 13: Halogen-free flexible cables having low emission of smoke
• Effective Date: 28-Jan-2023
• Referred By: EN 1047-2:2019 - Secure storage units - Classification and methods of test for resistance to fire - Part 2: Data rooms and data container
• Effective Date: 09-Feb-2026
• Referred By: EN 1648-1:2018 - Leisure accommodation vehicles - 12 V direct current extra low voltage electrical installations - Part 1: Caravans
• Effective Date: 09-Feb-2026
• Referred By: EN 1648-2:2018 - Leisure accommodation vehicles - 12 V direct current extra low voltage electrical installations - Part 2: Motor caravans
• Effective Date: 09-Feb-2026
• Referred By: EN 60335-1:2012/A13:2017 - Household and similar electrical appliances - Safety - Part 1: General requirements
• Effective Date: 03-Feb-2026
• Corrected By: EN 50525-3-21:2011/AC:2013 - Electric cables - Low voltage energy cables of rated voltages up to and including 450/750 V (U0/U) - Part 3-21: Cables with special fire performance - Flexible cables with halogen-free crosslinked insulation, and low emission of smoke
• Effective Date: 28-Jan-2023

Overview

EN 50525-3-21:2011, developed by CENELEC (CLC), specifies requirements for flexible low voltage energy cables with rated voltages up to and including 450/750 V (U0/U). These cables are characterized by their special fire performance: they use halogen-free, crosslinked insulation and sheathing compounds to ensure low emission of smoke and corrosive gases when exposed to fire. This standard is vital for applications where fire safety and minimization of toxic fumes are critical, such as public buildings, transport systems, and industrial installations.

The maximum conductor operating temperature for cables under this standard is 90°C. EN 50525-3-21 is intended to be used in conjunction with EN 50525-1, which contains the general requirements for low voltage energy cables.

Key Topics

• Fire Performance: The cables are designed to emit low amounts of smoke and virtually no halogens when exposed to fire, aiding in evacuation efforts and reducing damage to electronic equipment.
• Halogen-Free Crosslinked Insulation: Both insulation and sheath are of specialized crosslinked (thermoset) materials, specifically formulated to be free from halogens, minimizing corrosive gases during combustion.
• Testing and Compliance: Requirements for testing smoke emission (EN 61034-2) and halogen content are included to ensure product consistency and safety performance.
• Flexible Cable Construction: Covers single-core and multicore configurations for a range of applications.
• Marking and Identification: Cables compliant with EN 50525-3-21 must be marked with the CENELEC code H07ZZ-F and fulfill the identification requirements of EN 50525-1.

Applications

Flexible cables conforming to EN 50525-3-21:2011 are widely used in environments where both flexibility and enhanced fire safety are necessary. Key application areas include:

• Connection of Equipment and Machinery: Suitable for connecting mobile equipment and machinery to the fixed power supply, particularly where movement or vibration occurs.
• Public and Commercial Buildings: Used in hospitals, schools, airports, shopping centers, and other public locations, improving fire safety by reducing smoke and corrosive emissions in emergencies.
• Transport Infrastructure: Ideal for metro stations, railway stations, airports, and tunnels where cable fires could impact safe evacuation and equipment integrity.
• Industrial Facilities: Provides additional safety in data centers, factories, and critical installations where low smoke and halogen-free performance prevent damage and facilitate emergency response.
• Compliance and Safety: Meets stringent regulatory and insurance requirements for fire performance in sensitive environments.

Related Standards

• EN 50525-1: General requirements for low voltage energy cables, to be used in conjunction with EN 50525-3-21.
• EN 61034-2: Specifies test procedures for measuring smoke density of cables in fire conditions.
• EN 50363-5 / EN 50363-6: Define materials for halogen-free, crosslinked insulation and sheathing.
• EN 60332-1-2 and EN 60332-3-24: Outline fire testing for vertical flame propagation for single and bunched cables.
• EN 60228: Conductors of insulated cables.
• HD 516: Provides guidance for safe use of cables specified in the EN 50525 series.

EN 50525-3-21:2011 supports safer electrical installations by specifying flexible, low voltage cables optimized for environments requiring superior fire performance and reduced emission hazards. Compliance with this standard ensures robust, reliable, and safer cable installations across a range of industries, fulfilling both regulatory and operational demands.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2011
(OHNWULþQLNDEOL1L]NRQDSHWRVWQLHQHUJHWVNLNDEOL]QD]QDþHQRQDSHWRVWMRGR
YNOMXþQR988GHO.DEOLVSRVHEQLPLRJQMHYDUQLPLODVWQRVWPL
=YLMDYLNDEOL]]DPUHåHQRL]RODFLMREUH]KDORJHQRYLQ]QL]NRHPLVLMRGLPD
Electric cables - Low voltage energy cables of rated voltages up to and including 450/750
V (U0/U) - Part 3-21: Cables with special fire performance - Flexible cables with halogen-
free crosslinked insulation, and low emission of smoke
Kabel und Leitungen - Starkstromleitungen mit Nennspannungen bis 450/750 V (U0/U) -
Teil 3-21: Leitungen mit verbessertem Verhalten im Brandfall - Flexible halogenfreie,
raucharme Leitungen mit vernetzter Isolierung
Câbles électriques - Câbles d’énergie basse tension de tension assignée au plus égale à
450/750 V (U0/U) - Partie 3-21: Câbles à performances spéciales au feu - Câbles
souples isolés en matériau élastomère réticulé sans halogène, à faible dégagement de
fumée
Ta slovenski standard je istoveten z: EN 50525-3-21:2011
ICS:
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
29.060.20 Kabli Cables
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 50525-3-21
NORME EUROPÉENNE
May 2011
EUROPÄISCHE NORM
ICS 29.060.20 Supersedes HD 22.13 S2:2007

English version
Electric cables -
Low voltage energy cables of rated voltages up to and including 450/750 V
(U /U) -
Part 3-21: Cables with special fire performance -
Flexible cables with halogen-free crosslinked insulation, and low emission
of smoke
Câbles électriques -  Kabel und Leitungen -
Câbles d’énergie basse tension de tension Starkstromleitungen mit Nennspannungen
assignée au plus égale à 450/750 V bis 450/750 V (U /U) -
(U /U) - Teil 3-21: Starkstromleitungen mit
Partie 3-21: Câbles à performances verbessertem Verhalten im Brandfall -
spéciales au feu - Flexible halogenfreie, raucharme
Câbles souples isolés en matériau Leitungen mit vernetzter Isolierung
élastomère réticulé sans halogène, à
faible dégagement de fumée
This European Standard was approved by CENELEC on 2011-01-17. 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, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50525-3-21:2011 E
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 20, Electric
cables.
The text of the draft was submitted to the formal vote and was approved by CENELEC as
EN 50525-3-21 on 2011-01-17.
This document, which is one of a multipart series, supersedes HD 22.13 S2:2007.

Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any
or all such patent rights.
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) 2012-01-17

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2014-01-17

___________
- 3 - EN 50525-3-21:2011
Contents
Page
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Heat resistant cables (90 °C) . 5
4.1 Heavy duty cables – H07ZZ-F . 5
4.2 Heavy duty multicore cables – H07ZZ-F . 6
Annex A (normative) Tests for cables to EN 50525-3-21 . 8
Annex B (normative) General data . 9
Annex C (normative) Requirements for compatibility test . 13
C.1 Test conditions . 13
C.2 Requirements . 13
Bibliography . 14
Tables
Table A.1 . 8
Table B.1 . 9
Table B.2 . 12
Table C.1 − Requirements . 13

1 Scope
EN 50525-3-21 applies to flexible cables, insulated and sheathed with halogen-free
crosslinked compound and having low emission of smoke and corrosive gases when exposed
to fire.
NOTE 1 Low emission of smoke is checked in accordance with EN 61034-2. Low emission of corrosive gases is checked as
part of the check for absence of halogens (see Annex B of EN 50525-1).
The cables are of rated voltage U /U 450/750 V.
The cables are intended for the connection of equipment and machinery to the fixed supply.
The maximum conductor operating temperature for each of the cables in this standard is
90 °C.
NOTE 2 HD 516 contains extensive guidance on the safe use of cables in this standard.
This EN 50525-3-21 should be read in conjunction with EN 50525-1, which specifies general
requirements.
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.
NOTE One or more references to the standards below are in respect of a specific sub-division of that standard,
for instance a clause, a table, a class or a type. Cross-references to these standards are undated and, at all times,
the latest version applies.
EN 50363-5 Insulating, sheathing and covering materials for low voltage energy
cables - Part 5: Halogen-free, cross-linked insulating compounds
EN 50363-6 Insulating, sheathing and covering materials for low voltage energy
cables - Part 6: Halogen-free, cross-linked sheathing compounds
EN 50395 Electrical test methods for low voltage energy cables
EN 50396 Non electrical test methods for low voltage energy cables
EN 50525-1 Electric cables - Low voltage energy cables of rated voltages up to
and including 450/750 V (U /U) - Part 1: General requirements
EN 60228 Conductors of insulated cables (IEC 60228)
EN 60332-1-2 Tests on electric and optical fibre cables under fire conditions -
Part 1-2: Test for vertical flame propagation for a single insulated
wire or cable - Procedure for 1 kW pre-mixed flame (IEC 60332-1-2)
EN 60332-3-24 Tests on electric and optical fibre cables under fire conditions –
Part 3-24: Test for vertical flame spread of vertically-mounted
bunched wires or cables - Category C (IEC 60332-3-24)
EN 60811-1-2 Insulating and sheathing materials of electric and optical cables -
Common test methods - Part 1-2: General application - Thermal
ageing methods (IEC 60811-1-2)
EN 60811-1-4 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)
EN 61034-2 Measurement of smoke density of cables burning under defined
conditions - Part 2: Test procedure and requirements (IEC 61034-2)

- 5 - EN 50525-3-21:2011
3 Terms and definitions
For the purposes of this document the terms and definitions given in Clause 3 of EN 50525-1
apply.
4 Heat resistant cables (90 °C)
4.1 Heavy duty cables – H07ZZ-F
4.1.1 Construction
4.1.1.1 Conductor
The conductor shall be class 5, according to EN 60228.
4.1.1.2 Sizes of cable
The sizes of cable shall be:
2 2
- single core – 1,5 mm to 630 mm ;
2 2
- 2 and 5 core – 1,0 mm to 25 mm ;
2 2
- 3 and 4 core – 1,0 mm to 300 mm .
4.1.1.3 Insulation
The insulation shall be a cross-linked compound, Type EI 8 to EN 50363-5, applied around
each conductor.
4.1.1.4 Assembly
The cores of cables having two to five cores shall be twisted together.

NOTE 1 A centre filler may be used.

NOTE 2 A tape may be applied around the core assembly before application of the sheath.
4.1.1.5 Sheath
The cores shall be covered with a sheath.

a) For cables with a specified sheath thickness up to and including 2,4 mm:
1) sheath in a single layer, cross-linked compound of type EM 8 to EN 50363-6.
b) For cables with a specified sheath thickness greater than 2,4 mm:
1) sheath either in a single layer, cross-linked compound of type EM 8 to EN 50363-6;
2) or in two layers, with the inner layer made of one of the cross-linked compounds
type EM 8 or EM 10 to EN 50363-6 and the outer layer of the cross-linked
compound type EM 8 to EN 50363-6.
The sheath applied in a single layer or the inner layer of the sheath in two layers shall, for
cables with two to five cores, fill the spaces between the cores. Where a tape of suitable

material is applied around the core assembly (see NOTE 2 to 4.1.1.4) this requirement shall
not apply, provided that the finished cables shall not have any substantial cavity in the outer
interstices between the cores.
4.1.1.6 Marking
The cable shall be marked with the CENELEC code H07ZZ-F. The marking shall comply with
Clause 6 of EN 50525-1.
4.1.2 Requirements
Each cable shall comply with the appropriate requirements given in EN 50525-1, and the
particular requirements of this Part.
Testing shall be in accordance with Annex A.
The dimensions of the cables shall conform to Table B.1 for the relevant size.
The requirements to be met for the compatibility test shall be as given in Annex C.
When tested in accordance with the method and p
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