SIST HD 60364-4-43:2023/oprAA:2025

Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against overcurrent

IEC 60364-4-43:2023 provides requirements for: - protection of live conductors, PEN conductors, PEM conductors, and PEL conductors against the harmful effects caused by overcurrent; - coordination of measures for protection against overcurrent. This fourth edition cancels and replaces the third edition published in 2008. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) the standard has been restructured, see Table 1 (Correspondence between IEC 60364‑4‑43:2008 and this document) below; b) the measure "automatic disconnection of supply" has been designated as the preferred measure for protection against overcurrent; c) all measures except the measure "automatic disconnection of supply" have been transferred into new normative annexes to indicate that these measures are usable in certain applications and under certain restricted conditions only (see Annex A, Annex B and Annex E); d) a new clause "Terms and definitions" has been added; e) new requirements have been added for the protection of the neutral or mid-point conductor (with and without triplen harmonics).

Errichten von Niederspannungsanlagen - Teil 4-43: Schutzmaßnahmen - Schutz bei Überstrom

Installations électriques à basse tension - Partie 4-43: Protection pour assurer la sécurité - Protection contre les surintensités

Nizkonapetostne električne inštalacije - 4-43. del: Zaščitni ukrepi – Nadtokovna zaščita - Dopolnilo AA.

General Information

• Status: Not Published
• Public Enquiry End Date: 30-Jul-2025
• ICS: 29.120.50 - Fuses and other overcurrent protection devices
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: ELI - Electrical and communication installations
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 13-Jun-2025
• Due Date: 31-Oct-2025
• Completion Date: 05-Aug-2025
• Ref Project: HD 60364-4-43:2023/prAA:2025 - Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against overcurrent

Relations

• Amends: SIST HD 60364-4-43:2023 - Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against overcurrent (IEC 60364-4-43:2023)
• Effective Date: 09-Apr-2024

Overview

HD 60364-4-43:2023/prAA:2025 (CLC) is a draft amendment to the harmonization document addressing protection against overcurrent in low-voltage electrical installations. Aligned with IEC 60364-4-43:2023, the amendment clarifies requirements for protecting live, PEN, PEM and PEL conductors from harmful effects of overcurrent and for coordinating overcurrent protection measures across an installation. It introduces structural and technical changes, designates automatic disconnection of supply as the preferred measure, and adds new normative and informative annexes (notably Annex G on device positioning).

Key topics and technical requirements

• Scope: Protection of conductors (live, neutral-related conductors) and coordination of overcurrent protective measures.
• Preferred measure: Automatic disconnection of supply is identified as the primary protection strategy; alternative measures are retained in new normative annexes (Annex A, B, E) for restricted applications.
• New definitions: A dedicated Terms and definitions clause has been added to improve clarity.
• Neutral/mid-point protection: New requirements cover protection of the neutral or mid-point conductor, including considerations with and without triplen harmonics.
• Positioning of protective devices (Annex G, normative):
  • Overcurrent devices shall generally be installed at the origin of each circuit unless exceptions apply.
  • Overload protection: devices should be placed where conductor current-carrying capacity is reduced, with limited exceptions (e.g., short inter-run up to 3 m under strict conditions).
  • Short-circuit protection: devices should be placed where let-through energy (k2S2) capability is reduced; limited placement exceptions mirror overload rules.
• National variations: Annex ZB (normative) and Annex ZC (informative) document special national conditions and A-deviations (examples include Italy, Germany, UK).

Practical applications

• Design and specification of LV distribution and branch circuits, ensuring compliant placement and selection of overcurrent protective devices.
• Protection coordination studies and discrimination between upstream/downstream devices.
• Safety risk reduction in installations with special conductor layouts, neutral/mid-point arrangements or harmonic distortion.
• National adoption and implementation by standards committees, utilities and regulators (CENELEC members) when the amendment is approved.

Who should use this standard

• Electrical designers and consulting engineers
• Installation contractors and site electricians
• Safety and compliance officers, asset owners, facility managers
• Distribution network operators and protection coordination engineers
• Testing laboratories and certification bodies

Related standards

• IEC 60364 series (especially IEC 60364-4-43:2023)
• National HD/EN publications and CENELEC harmonization documents (implementation and national deviations)

Keywords: HD 60364-4-43, protection against overcurrent, low-voltage electrical installations, overcurrent protection devices, automatic disconnection of supply, neutral conductor protection, triplen harmonics, Annex G, CENELEC.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2025
Nizkonapetostne električne inštalacije - 4-43. del: Zaščitni ukrepi - Zaščita pred
nadtoki - Dopolnilo AA
Low-voltage electrical installations - Part 4-43: Protection for safety - Protection against
overcurrent
Errichten von Niederspannungsanlagen - Teil 4-43: Schutzmaßnahmen - Schutz bei
Überstrom
Installations électriques à basse tension - Partie 4-43: Protection pour assurer la sécurité
- Protection contre les surintensités
Ta slovenski standard je istoveten z: HD 60364-4-43:2023/prAA:2025
ICS:
29.120.50 Varovalke in druga Fuses and other overcurrent
nadtokovna zaščita protection devices
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

HARMONIZATION DOCUMENT DRAFT
HD 60364-4-43:2023
DOCUMENT D'HARMONISATION
HARMONISIERUNGSDOKUMENT
prAA
June 2025
ICS 91.140.50; 29.120.50 -
English Version
Low-voltage electrical installations - Part 4-43: Protection for
safety - Protection against overcurrent
Installations électriques à basse tension - Partie 4-43: Errichten von Niederspannungsanlagen - Teil 4-43:
Protection pour assurer la sécurité - Protection contre les Schutzmaßnahmen - Schutz bei Überstrom
surintensités
This draft amendment prAA, if approved, will modify the Harmonization Document HD 60364-4-43:2023; it is submitted to CENELEC
members for enquiry.
Deadline for CENELEC: 2025-08-29.

It has been drawn up by CLC/TC 64.

If this draft becomes an amendment, CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for implementation of this amendment on a national level.

This draft amendment, was established by CENELEC in three official versions (English, French, German).

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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the 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 Harmonization Document. It is distributed for review and comments. It is subject to change without notice
and shall not be referred to as a Harmonization Document.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Project: 79835 Ref. No. HD 60364-4-43:2023/prAA:2025 E

Contents Page
1 European foreword . 3
2 1 Modification to Subclause 431.4, “Protection against overload current” . 4
3 2 Modification to Subclause 431.5, “Protection against short-circuit currents” . 4
4 3 Addition of Annex G, “Position of overcurrent protection devices” . 4
5 Annex G (normative) Position of overcurrent protection devices. 5
6 G.1 General . 5
7 G.2 Positioning of devices for overload protection . 5
8 G.3 Positioning of devices for short-circuit protection . 6
9 4 Addition of Annex ZB, “Special national conditions” and Annex ZC, “A-deviations” . 6
10 Annex ZA (normative)  Special national conditions. 7
11 Annex ZB (informative) A-deviations . 8
12 European foreword
13 This document (HD 60364-4-43:2023/prAA:2025) has been prepared by CLC/TC 64 “Electrical installations
14 and protection against electric shock”.
15 This document is currently submitted to the Enquiry.
16 The following dates are proposed:
• latest date by which the existence of this (doa) dav + 6 months
document has to be announced at national
level
• latest date by which this document has to be (dop) dav + 12 months
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) dav + 36 months
conflicting with this document have to be (to be confirmed or
withdrawn modified when voting)
17 1 Modification to Subclause 431.4, “Protection against overload current”
18 In 431.4.1, add the following paragraph:
19 “The positioning of overcurrent protective devices for protection against overload currents shall meet the
20 requirements provided in Annex G.”
21 2 Modification to Subclause 431.5, “Protection against short-circuit currents”
22 In 431.5.1, replace Note 1 with the following paragraph:
23 “The positioning of overcurrent protective devices for protection against short-circuit currents shall meet the
24 requirements provided in Annex G.”
25 3 Addition of Annex G, “Position of overcurrent protection devices”
26 Add the following new normative Annex G:
27 “
28 Annex G
29 (normative)
31 Position of overcurrent protection devices
32 G.1 General
33 Devices for overload and/or short-circuit protection shall be installed at the origin of each circuit unless the
34 exceptions of G.2 and/or G.3 are applied.
35 G.2 Positioning of devices for overload protection
36 G.2.1 A device for protection against overload shall be placed at each point where there is a reduction in the
37 value of current-carrying capacity of the conductors except where A.2, G.2.2, G.2.3, or G.2.4 apply. The
38 requirements in G.2.2 to G.2.4 shall not be applied to installations situated in locations presenting a fire risk or
39 risk of explosion.
40 NOTE A reduc
...