EN 3475-408:2025

Aerospace series - Cables, electrical, aircraft use - Test methods - Part 408: Fire resistance

This document specifies a method of testing the fire resistance of "fire-proof" electrical cables.

Luft- und Raumfahrt - Elektrische Leitungen für Luftfahrtverwendung - Prüfverfahren - Teil 408: Feuerbeständigkeit

No Scope available

Série aérospatiale - Câbles électriques à usage aéronautique - Méthodes d'essais - Partie 408 : Résistance au feu

Le présent document spécifie une méthode pour soumettre à essai la résistance au feu des câbles électriques ignifuges.

Aeronavtika - Električni kabli za uporabo v zračnih plovilih - Preskusne metode - 408. del: Požarna odpornost

General Information

• Status: Not Published
• Publication Date: 23-Dec-2025
• ICS: 49.060 - Aerospace electric equipment and systems
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 2/S 2 - Cables & Stripping Tools
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Start Date: 26-Oct-2025
• Completion Date: 26-Oct-2025
• Ref Project: kSIST FprEN 3475-408:2025 - Aerospace series - Cables, electrical, aircraft use - Test methods - Part 408: Fire resistance

Relations

• Revises: EN 3475-408:2005 - Aerospace series - Cables, electrical, aircraft use - Test methods - Part 408: Fire resistance
• Effective Date: 28-Jan-2023

Overview

EN 3475-408:2025 is a critical European standard developed by CEN under the Aerospace and Defence Industries Association of Europe (ASD-STAN). This standard outlines the test methods for assessing the fire resistance of electrical cables specifically designed for aircraft use. As an update to the previous EN 3475-408:2005, this 2025 revision introduces enhanced technical requirements, including liquid burner specifications and test setup configurations to ensure the highest safety standards in aerospace applications.

The document details procedures to evaluate the fire resistance capabilities of "fire-proof" electrical cables used in the aerospace sector, addressing both single-core and multi-core cables. Proper adherence to this standard is essential for manufacturers and testing laboratories aiming to certify aerospace electrical cables against stringent fire safety norms.

Key Topics

• Scope and Application
  Focused on specifying methods for fire resistance testing of electrical cables used in aircraft, ensuring safe operation under extreme fire exposure.

• Test Specimen Preparation
  Selection of six specimens at a minimum length of 0.75 meters, with procedures for immersion in test fluids relevant to aerospace environments (e.g., kerosene, phosphate-based hydraulic fluid, synthetic oil, isopropyl alcohol, ethylene glycol).

• Burner Types and Calibration
  Two burner methods are specified:

  • Method A: Utilizes liquid combustible (kerosene) with defined flame characteristics at 1100 °C ± 80 °C and a heat flux density of 116 kW/m² ± 10 kW/m².
  • Method B: Uses gas combustible with similar flame temperature and heat flux requirements.
    Burner calibration is rigorously defined for temperature measurement using thermocouples and heat flux measurement using copper tube calorimeters to ensure test consistency.

• Test Fixture and Setup
  The standard requires a test fixture capable of holding specimens securely with specified vibration parameters (frequency ~30 Hz, 4 g acceleration) to simulate operational conditions. Fixture orientation differs by burner type (vertical for gas, horizontal for liquid).

• Measurement and Monitoring
  For single-core cables, current leakage detection is mandatory via nickel-plated copper strand wrapping. This ensures integrity assessment during fire exposure.

• Burner Distance and Exposure Conditions
  Critical dimensions between burner nozzle and specimen as per ISO 2685 standards guarantee that the fire resistance testing accurately replicates aircraft fire scenarios.

Applications

EN 3475-408:2025 is essential for manufacturers, test laboratories, and regulatory authorities involved in the aerospace sector. The standard enables:

• Certification of Aircraft Electrical Cables
  Ensuring cables meet fire resistance performance expected in the harsh flight environment, thereby enhancing flight safety.

• Quality Assurance in Aerospace Cable Production
  Providing a benchmark test methodology to validate cable designs and materials against fire hazards.

• Regulatory Compliance and Safety Assurance
  Supporting compliance with global aerospace regulations that mandate stringent fire safety measures for all electrical wiring systems aboard aircraft.

• Research and Development
  Guiding R&D teams in designing cables with superior fire-resistant materials and construction techniques by providing standardized testing criteria.

Related Standards

• EN 3909 – Aerospace series Test fluids and test methods for electrical and optical components and sub-assemblies, referenced for the preparation of test fluids in EN 3475-408.

• ISO 2685:1998 – Aircraft environmental test procedures for resistance to fire in designated fire zones; provides the fundamental burner specifications and calibration methods referenced by EN 3475-408.

• AECMA Prestandard (Historical Reference) – The aerospace cable testing guidelines preceding the EN 3475-408 standard.

Conclusion

EN 3475-408:2025 defines a comprehensive and technically robust methodology for testing the fire resistance of aerospace-grade electrical cables. Implementation of this standard plays a vital role in ensuring that electrical wiring systems in aircraft can withstand fire incidents, thereby protecting passengers, aircrew, and equipment. For manufacturers and testing facilities, adherence to EN 3475-408:2025 is indispensable for achieving certification, maintaining quality, and meeting international aerospace safety regulations.

Keywords: aerospace electrical cables, fire resistance test, aircraft cable fire safety, EN 3475-408:2025, cable burn test, ISO 2685, EN 3909, aircraft electrical wiring standards, aerospace cable certification, fire-proof cables

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 3475-408:2023
01-junij-2023
Aeronavtika - Električni kabli za uporabo v zračnih plovilih - Preskusne metode -
408. del: Požarna odpornost
Aerospace series - Cables, electrical, aircraft use - Test methods - Part 408: Fire
resistance
Luft- und Raumfahrt - Elektrische Leitungen für Luftfahrtverwendung - Prüfverfahren -
Teil 408: Feuerbeständigkeit
Série aérospatiale - Câbles électriques à usage aéronautique - Méthodes d’essais -
Partie 408: Résistance au feu
Ta slovenski standard je istoveten z: prEN 3475-408
ICS:
29.060.20 Kabli Cables
49.060 Letalska in vesoljska Aerospace electric
električna oprema in sistemi equipment and systems
oSIST prEN 3475-408:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 3475-408:2023
oSIST prEN 3475-408:2023
DRAFT
EUROPEAN STANDARD
prEN 3475-408
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2023
ICS 49.060 Will supersede EN 3475-408:2005
English Version
Aerospace series - Cables, electrical, aircraft use - Test
methods - Part 408: Fire resistance
Série aérospatiale - Câbles électriques à usage Luft- und Raumfahrt - Elektrische Leitungen für
aéronautique - Méthodes d'essais - Partie 408: Luftfahrtverwendung - Prüfverfahren - Teil 408:
Résistance au feu Feuerbeständigkeit
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN 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.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 3475-408:2023 E
worldwide for CEN national Members.

oSIST prEN 3475-408:2023
prEN 3475-408:2023 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Preparation of specimens . 4
5 Apparatus . 4
5.1 List of apparatus . 4
5.2 Burner . 4
5.2.1 Method A – Liquid combustible (kerosene) . 4
5.2.2 Method B – Gas combustible . 5
5.2.3 Burner calibration . 5
5.3 Test fixture . 7
5.4 Test fluids . 9
6 Method . 10
6.1 Preparation . 10
6.1.1 General. 10
6.1.2 Single core cable . 10
6.1.3 Multi core and screen cables . 11
6.2 Procedure . 11
7 Requirements . 13

oSIST prEN 3475-408:2023
prEN 3475-408:2023 (E)
European foreword
This document (prEN 3475-408:2023) has been prepared by the Aerospace and Defence Industries
Association of Europe — Standardization (ASD-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 3475-408:2005.
prEN 3475-408:2023 includes the following significant technical changes with respect to
EN 3475-408:2005:
a) Introduction of liquid burner requirements with test setup configuration.
oSIST prEN 3475-408:2023
prEN 3475-408:2023 (E)
1 Scope
This document specifies a method of testing the fire resistance of “fire-proof” electrical cables.
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.
EN 3909, Aerospace series — Test fluids and test methods for electrical and optical components and sub-
assemblies
ISO 2685:1998, Aircraft — Environmental test procedure for airborne equipment — Resistance to fire in
designated fire zones
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Preparation of specimens
Six test specimens, 0,75 m minimum length, shall be selected at random from a quantity of cable.
5 Apparatus
5.1 List of apparatus
The following shall be required for this test: a burner, a burner calibration, a test fixture, and test fluids.
5.2 Burner
5.2.1 Method A – Liquid combustible (kerosene)
The burner shall be as described in ISO 2685:1998, Clause A.2 or any other burner or assembly of burners
satisfying the following conditions:
— liquid combustible type of kerosene shall be in accordance with EN 3909;
— the burner outlet shall be equipped with an extension of 318 mm, 152 mm high and 280 mm width;
— cable length exposed to the flame: 152 mm;
— flame characteristics as per ISO 2685:
— temperature: 1 100 °C ± 80 °C;

Published as AECMA Prestandard at the date of publication of this standard.
oSIST prEN 3475-408:2023
prEN 3475-408:2023 (E)
— heat flux density received by the calorimeter described in ISO 2685:1998, Annex B:
2 2
116 kW/m ± 10 kW/m .
5.2.2 Method B – Gas combustible
The burner shall be as described in ISO 2685:1998, Annex A or any other burner or assembly of burners
satisfying the following conditions:
— cable length exposed to the flame: 152 mm;
— diameter or width of the flame at the base of the burner(s) ≥ 2 D (D diameter of the cable under test);
— Flame characteristics as per ISO 2685:
— temperature: 1 100 °C ± 80 °C;
— heat flux density received by the calorimeter described in ISO 2685:1998, Annex B:
2 2
116 kW/m ± 10 kW/m .
5.2.3 Burner calibration
5.2.3.1 Temperature
5.2.3.1.1 Temperature measurement
The calibration in temperature of the burner consists of adjusting the mixing ratio of air and combustible,
until the flame is delivering a standard flame. A flame is characterized by its temperature and its heat
flux. As the quantitative value is directly dependent on the instrumentation, it is necessary to respect a
common tool to ensure uniformity between tests.
Before calibrating the burner, allow the apparatus to run for at least 5 min for stabilizing the heating
conditions.
During and after calibration, the burner shall not be extinguished until the end of the fire test.
The surface calibrated is only valid as long as the burner settings was not changed or turned off.
The temperature of each thermocouple shall be recorded at least every 5 s intervals during minimum
2 min.
5.2.3.1.2 Temperature measuring equipment
It is important that the temperature measuring equip
...