prEN 2665-004
(Main)Aerospace series - Circuit breakers, three-pole, temperature compensated, rated current 20 A to 50 A - Part 004: UNC thread terminals - Product standard
General Information
- Abstract
This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 20 A to 50 A, used in aircraft on-board circuits at a temperature between −55 °C and 90 °C at an altitude of 15 000 m max.
These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action "trip-free" tripping
They will continue to function up to the short-circuit current.
- Status
- Not Published
- Publication Date
- 14-Feb-2028
- Technical Committee
- ASD-STAN - Aerospace
- Drafting Committee
- ASD-STAN/D 2/S 5 - Protection Devices
- Current Stage
- 4020 - Submission to enquiry - Enquiry
- Start Date
- 20-Aug-2026
- Completion Date
- 20-Aug-2026
Overview
prEN 2665-004 is a draft European Standard developed by CEN for the aerospace industry, detailing the product standard for three-pole, temperature compensated circuit breakers with rated currents from 20 A to 50 A. These circuit breakers are intended for use in aircraft on-board electrical systems, supporting operation in challenging environments - specifically at temperatures from −55 °C to 90 °C and at altitudes up to 15,000 meters. Featuring UNC thread terminals and operated via a push-pull single pushbutton actuator with delayed, trip-free tripping action, this standard defines the critical characteristics to ensure reliability, safety, and interoperability in aerospace applications.
Key Topics
Scope of Use
- Designed for aircraft on-board circuits
- Rated currents: 20 A to 50 A
- Operates at extreme temperatures and altitudes
- Resilient to vibrations, shocks, humidity, and corrosion
Circuit Breaker Operation
- Three-pole configuration
- Temperature compensated for stable performance
- Actuated by a push-pull type single pushbutton
- Features delayed action and “trip-free” mechanism
- Maintains operation up to short-circuit current
Mechanical and Electrical Requirements
- Dimensions: in millimetres; terminal thread 8-32 UNC
- Mass: maximum 180 g with hardware
- Panel mounting: in accordance with EN 2665-001
- Fasteners: in line with EN 6113
- Tightening torques prescribed for both attaching nuts and connection hardware
- Resistance to vibration: tested under multiple scenarios at varying temperatures and altitudes
Environmental Endurance
- Humidity, corrosion, and contaminating liquids resistance
- Capable of withstanding overvoltage from lightning
- Endurance for 2,500 load and 5,000 no-load operations at operational voltages
Electrical Performance
- Operational voltage: 115 V to 200 V AC, 360 Hz to 800 Hz, three-phase
- Controlled voltage drop for each rating
- Defined minimum and maximum tripping thresholds and overload trip times
- Validated under short-circuit currents up to 2,000 A RMS
- Strong insulation and dielectric rigidity as specified for aviation safety
Applications
Commercial and Military Aircraft:
prEN 2665-004 covers circuit breakers suitable for power distribution and protection in both fixed-wing aircraft and helicopters.Aerospace Electrical Systems:
Ensures that circuit protection devices meet standardized performance levels, improving safety, reliability, and maintenance efficiency in onboard systems.High-Reliability Environments:
The temperature and altitude range make these circuit breakers ideal for other aerospace and defense scenarios where robust, enduring protection is required.Panel and Equipment Mounting:
The standard enables straightforward integration into control panels and electrical enclosures used in avionic systems, reduced installation risks, and ensured system compatibility using UNC-thread terminal hardware.
Related Standards
- EN 2350 – Aerospace series: Generic requirements for circuit breakers
- EN 2665-001 – Technical specification for temperature compensated, three-pole circuit breakers
- EN 3841-305 – Test methods for aerospace circuit breakers, including short-circuit performance
- EN 6113 – Connecting and attachment hardware for aerospace circuit breakers
- SAE-AMS-STD-595 – Color requirements for government procurement
- TR 6083 – Standard for cut-outs for installation of electrical components
prEN 2665-004 supports the aerospace sector by providing a consistent, industry-wide benchmark for selecting and implementing three-pole, temperature compensated circuit breakers with UNC thread terminals. Compliance with this standard helps to ensure the safety, reliability, and interoperability of vital electrical protection devices in demanding aircraft environments.
Relations
- Effective Date
- 08-Jan-2025
Get Certified
Connect with accredited certification bodies for this standard
BUREAU VERITAS Certification Germany
Bureau Veritas certification in Germany.
Element Materials Technology
Materials testing and product certification.
AQMS Ltd.
AQMS provides ISO certification to SMEs across the UK.
Sponsored listings
Frequently Asked Questions
prEN 2665-004 is a draft published by the European Committee for Standardization (CEN). Its full title is "Aerospace series - Circuit breakers, three-pole, temperature compensated, rated current 20 A to 50 A - Part 004: UNC thread terminals - Product standard". This standard covers: This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 20 A to 50 A, used in aircraft on-board circuits at a temperature between −55 °C and 90 °C at an altitude of 15 000 m max. These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action "trip-free" tripping They will continue to function up to the short-circuit current.
This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 20 A to 50 A, used in aircraft on-board circuits at a temperature between −55 °C and 90 °C at an altitude of 15 000 m max. These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action "trip-free" tripping They will continue to function up to the short-circuit current.
prEN 2665-004 is classified under the following ICS (International Classification for Standards) categories: 49.060 - Aerospace electric equipment and systems. The ICS classification helps identify the subject area and facilitates finding related standards.
prEN 2665-004 has the following relationships with other standards: It is inter standard links to EN 2665-004:2013. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
prEN 2665-004 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2026
Aeronavtika - Odklopniki, tripolni, temperaturno kompenzirani, za naznačene
tokove od 20 A do 50 A - 004. del: UNC-navojni priključki - Standard za proizvod
Aerospace series - Circuit breakers, three-pole, temperature compensated, rated current
20 A to 50 A - Part 004: UNC thread terminals - Product standard
Luft- und Raumfahrt - Schutzschalter, dreipolig, temperaturkompensiert, Nennströme
von 20 A bis 50 A - Teil 004: UNC-Klemmengewinde - Produktnorm
Série aérospatiale - Disjoncteurs tripolaires compensés en température, intensités
nominales 20 A à 50 A - Partie 004 : Bornes à filetage UNC - Norme de produit
Ta slovenski standard je istoveten z: prEN 2665-004
ICS:
49.060 Letalska in vesoljska Aerospace electric
električna oprema in sistemi equipment and systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2026
ICS 49.060 Will supersede EN 2665-004:2013
English Version
Aerospace series - Circuit breakers, three-pole,
temperature compensated, rated current 20 A to 50 A -
Part 004: UNC thread terminals - Product standard
Série aérospatiale - Disjoncteurs tripolaires compensés Luft- und Raumfahrt - Schutzschalter, dreipolig,
en température, intensités nominales 20 A à 50 A - temperaturkompensiert, Nennströme von 20 A bis 50
Partie 004 : Bornes à filetage UNC - Norme de produit A - Teil 004: UNC-Klemmengewinde - Produktnorm
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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 2665-004:2026 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Dimensions and mass . 4
4.1 Dimensional characteristics . 4
4.2 Electrical diagram . 6
4.3 Mass . 6
4.4 Panel mounting . 6
5 Characteristics . 6
5.1 Material, surface treatment . 6
5.2 Mechanical characteristics . 6
5.2.1 Fasteners . 6
5.2.2 Recommended tightening torque of attaching nut for installation . 6
5.2.3 Recommended tightening torque of connection hardware for installation . 6
5.2.4 Resistance to vibrations . 7
5.2.5 Resistance to shocks . 7
5.2.6 Mechanical endurance . 7
5.3 Environment characteristics . 7
5.3.1 Humidity . 7
5.3.2 Corrosion . 7
5.3.3 Contaminating liquids . 7
5.3.4 Overvoltage caused by lightning . 7
5.4 Electrical characteristics . 7
5.4.1 Nominal voltage of operational circuits . 7
5.4.2 Voltage drop at Ι . 7
n
5.4.3 Minimum and maximum tripping thresholds . 8
5.4.4 Overload trip . 8
5.4.5 Short-circuit values . 8
5.4.6 No-load and load endurance . 9
5.4.7 Dielectric rigidity . 9
5.4.8 Insulation resistance . 10
6 Designation . 10
7 Rated current code . 10
8 Delivery codes . 10
9 Marking . 11
10 Technical specification . 11
Bibliography . 12
European foreword
This document (prEN 2665-004:2026) has been prepared by 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 2665-004:2013.
...