prEN 2794-004

• Abstract:

  This document specifies the characteristics of single-pole circuit breakers, temperature compensated with a rated current from 20 A to 25 A, used in aircraft on-board circuits at a temperature between −55 °C and 125 °C and at an altitude of 15 000 m max.; These circuit breakers are operated by a push-pull type single push button (actuator), with delayed action “trip-free” tripping.; They will continue to function up to the short-circuit current.

• Status: Not Published
• Publication Date: 03-Jan-2028
• ICS: 49.060 - Aerospace electric equipment and systems
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 2/S 5 - Protection Devices
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 13-Aug-2026
• Completion Date: 13-Aug-2026
• Ref Project: oSIST prEN 2794-004:2026 - Aerospace series - Circuit breakers, single-pole, temperature compensated, rated currents 20 A to 60 A - Part 004: UNC thread terminals - Product standard

• Revises: EN 2794-004:2014 - Aerospace series - Circuit breakers, single-pole, temperature compensated, rated currents 20 A to 50 A - Part 004: UNC thread terminals - Product standard
• Effective Date: 08-Jan-2025

prEN 2794-004 is a draft European Standard from the European Committee for Standardization (CEN) for aerospace single-pole, temperature compensated circuit breakers with UNC thread terminals. It specifies the product characteristics, installation data, marking, and test-related performance for circuit breakers used in aircraft on-board circuits.

What does prEN 2794-004 specify?

prEN 2794-004 specifies the characteristics of single-pole circuit breakers, temperature compensated, for aircraft on-board circuits. The scope places them in service between -55 °C and 125 °C and up to 15 000 m altitude, with push-pull single push button operation and delayed action “trip-free” tripping.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Dimensions and mass
• Clause 5 - Characteristics
• Clause 6 - Designation
• Clause 7 - Rated current code
• Clause 8 - Delivery hardware code
• Clause 9 - Marking
• Clause 10 - Technical specification
• Bibliography

For a buyer, engineer, or quality manager, this means the standard is a product standard rather than a general theory document. It defines how the breaker is built, identified, installed, and verified.

What are the key requirements of prEN 2794-004?

prEN 2794-004 sets out the main design, installation, environmental, and electrical requirements for the breaker. The most practical items are the installation dimensions, mounting hardware, operating thresholds, and short-circuit performance.

Dimensions, fit, and mounting

Clause 4 requires the configuration, dimensions, and tolerances to follow Figure 1, and the electrical diagram to follow Figure 2. The breaker has to fit the panel cut-out given by EN 2794-001, and the document also gives a maximum mass of 70 g for delivery code A including hardware.

In practice, this is the information needed to check panel compatibility, connector orientation, and installed weight.

Materials and hardware

Clause 5.1 points to EN 2794-001 for material and surface treatment. Clause 5.2.1 requires fasteners in accordance with EN 6113, and Clauses 5.2.2 and 5.2.3 give installation tightening torques for the attaching nut and connection hardware.

In practice, this tells the installer which hardware to use and how tightly to assemble it, so the breaker is mounted and connected consistently.

Mechanical and environmental performance

Clause 5.2 covers resistance to vibration, shock, and mechanical endurance, while Clause 5.3 covers humidity, corrosion, contaminating liquids, and overvoltage caused by lightning. Several of these requirements refer back to EN 2794-001.

In practice, this means the breaker is defined for aircraft conditions that include vibration, shock, and environmental exposure, not just bench operation.

Electrical performance

Clause 5.4 defines the electrical behavior. It covers nominal operational voltage, voltage drop at rated current, minimum and maximum tripping thresholds, overload trip behavior, short-circuit values, endurance under load and no-load, dielectric rigidity, and insulation resistance.

The short-circuit requirements are especially important because the breaker has to continue functioning up to the short-circuit current. Clause 5.4.5 gives the test conditions for both 28 V DC and 115 V AC, with operations defined using CO and OCO actions from EN 3841-305.

Identification and ordering

Clauses 6 to 8 define the designation, the rated current code, and the delivery hardware code. Clause 9 then sets the marking content, including the designation, manufacture date, manufacturer identification, diagram and terminal identification, and the manufacturer’s part number.

In practice, these clauses are what allow procurement, traceability, and installation teams to order and identify the correct breaker variant.

Technical specification linkage

Clause 10 requires the technical specification to be in accordance with EN 2794-001.

In practice, this makes prEN 2794-004 a part-specific document that relies on a shared technical base from the companion standard.

What terms does prEN 2794-004 define?

prEN 2794-004 uses the terms and definitions from EN 2350. The following terms and abbreviations are important for reading the document:

• Actuator - the push-pull single push button that operates the breaker.
• Trip-free - the tripping mode named in the scope for delayed action release behavior.
• Rated current - the current level used to classify and mark the breaker.
• Operational circuits - the circuits for which the nominal voltage is specified in Clause 5.4.1.
• CO - break operation, as referenced in the short-circuit test note from EN 3841-305.
• OCO - make operation, also referenced in the short-circuit test note from EN 3841-305.
• Delivery hardware code - the code used in Clause 8 to identify the supplied hardware kit.
• Technical specification - the companion specification required by Clause 10.

Who uses prEN 2794-004?

prEN 2794-004 is used by manufacturers of aerospace circuit breakers, aircraft electrical equipment suppliers, test laboratories, and specification or procurement teams. It is relevant to anyone defining, qualifying, ordering, or checking single-pole circuit breakers for aircraft on-board circuits.

In practice, design engineers use it to match dimensions and electrical behavior, quality teams use it for verification and acceptance, and buyers use it to specify the correct product and hardware kit.

What changed in prEN 2794-004 from the previous edition?

prEN 2794-004 will supersede EN 2794-004:2014. The document states these technical changes:

• short-circuit values in Table 5 were modified;
• the mass in Clause 4.3 was changed from 62 g to 70 g;
• the external diameter of the button in Figure 1 was revised.

Which standards are used with prEN 2794-004?

prEN 2794-004 cites these related documents:

• EN 2350 - provides the terms and definitions used in the document, and the general technical specification for aerospace circuit breakers.
• EN 2794-001 - provides the companion technical specification and is also used for the panel cut-out, materials, environmental characteristics, and insulation resistance.
• EN 3841-305 - provides the short-circuit test method and the definitions of break operation (CO) and make operation (OCO).
• EN 6113 - specifies the connecting and attachment hardware.
• SAE-AMS-STD-595 - provides the color reference used for the black color callout in Figure 1.
• TR 6083 - provides cut-outs for installation of electrical components and is referenced for the panel positioning lug.

What does the prEN 2794-004 document contain?

prEN 2794-004 contains one configuration figure, one electrical diagram, and several tables covering voltage, tripping thresholds, overload trip behavior, short-circuit values, endurance, dielectric rigidity, rated current codes, and delivery hardware codes. It also includes detailed notes on test conditions such as altitude, current type, frequency range, and operation sequences.

The document is built for specification, installation, and qualification work. Its content supports dimensional checking, hardware selection, environmental and electrical testing, and marking verification.

It also gives the wording and structure needed to identify the breaker variant on the product and packaging. That makes the document useful both at design stage and during acceptance or traceability checks.

SLOVENSKI STANDARD
01-oktober-2026
Aeronavtika - Odklopniki, enopolni, temperaturno kompenzirani, naznačeni tok od
20 A do 50 A - 004. del: Navojni priključki UNC - Standard za proizvod
Aerospace series - Circuit breakers, single-pole, temperature compensated, rated
currents 20 A to 60 A - Part 004: UNC thread terminals - Product standard
Luft- und Raumfahrt - Schutzschalter, einpolig, temperaturkompensiert, Nennströme von
20A bis 50A - Teil004: UNC-Klemmengewinde - Produktnorm
Série aérospatiale - Disjoncteurs unipolaires 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 2794-004
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 2794-004:2014
English Version
Aerospace series - Circuit breakers, single-pole,
temperature compensated, rated currents 20 A to 60 A -
Part 004: UNC thread terminals - Product standard
Série aérospatiale - Disjoncteurs unipolaires Luft- und Raumfahrt- Schutzschalter, einpolig,
compensés en température, intensités nominales 20 A temperaturkompensiert, Nennströme von 20A bis 50A-
à 50 A - Partie 004 : Bornes à filetage UNC - Norme de Teil004: UNC-Klemmengewinde- Produktnorm
produit
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 2794-004:2026 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 cut-out . 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 . 8
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 hardware code . 11
9 Marking . 11
10 Technical specification . 11
Bibliography . 12

European foreword
This document (prEN 2794-004:2026) 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 pr
...