SIST EN 50171:2022/oprA1:2026
(Amendment)Central safety power supply systems
- Abstract
This document specifies the general requirements for central power supply systems for an independent energy supply to essential safety equipment. This standard covers systems that are permanently connected to AC supply voltages not exceeding 1 000 V and use batteries as an alternative power source.
Central safety power supply systems are intended to ensure energy supply to emergency escape lighting in the event of normal supply failure and may be suitable for energizing other essential safety equipment, for example:
– electric circuits of automatic fire extinguishing installations;
– paging systems and signalling safety installations;
– smoke extraction equipment;
– carbon monoxide warning systems;
– special safety installations related to specific buildings, e.g. high-risk areas.
The power supply of CPS systems should be dedicated only to the essential safety equipment, and not for other type of loads such as general purpose IT or industrial systems etc.
Combinations of the aforementioned safety equipment types are permitted together on the same central safety power supply system providing the availability for safety equipment loads is not impaired. A fault occurring in a circuit should not cause the interruption in any other circuit used to supply essential safety equipment.
Schematic representations of typical central safety power supply equipment are depicted in Clause 4.
Power supply systems for fire alarm equipment that are covered by EN 54 (series) are excluded.
- Status
- Not Published
- Public Enquiry End Date
- 30-Jul-2026
- Technical Committee
- MOV - Measuring equipment for electromagnetic quantities
- Current Stage
- 4020 - Public enquire (PE) (Adopted Project)
- Start Date
- 26-May-2026
- Due Date
- 13-Oct-2026
- Completion Date
- 24-Sep-2026
SIST EN 50171:2022/oprA1:2026 is an amendment to EN 50171:2021 for central safety power supply systems. It specifies requirements for permanently connected AC systems up to 1 000 V that use batteries as the alternative power source for essential safety equipment. The document focuses on emergency escape lighting and other safety loads that must keep working when the normal supply fails.
What does SIST EN 50171:2022/oprA1:2026 specify?
SIST EN 50171:2022/oprA1:2026 specifies the general requirements for central power supply systems that provide independent energy for essential safety equipment. In practice, it is the standard for battery-backed central supplies that must keep safety circuits energized during a mains failure.
The scope covers systems dedicated to essential safety equipment such as:
- emergency escape lighting
- automatic fire extinguishing installations
- paging systems and signalling safety installations
- smoke extraction equipment
- carbon monoxide warning systems
- special safety installations for specific buildings, including high-risk areas
The power supply should be used only for essential safety loads, not for general IT or industrial loads. Different safety loads may be combined on the same system if their availability is not impaired, and a fault in one circuit must not interrupt another safety circuit. Fire alarm equipment covered by the EN 54 series is outside the scope.
The document is organized as amendments to Clause 1 on scope, Clause 2 on normative references, Clause 3 on terms and definitions, Clause 4 on operating modes, Clause 5 on normal operating conditions and user-specified requirements, and Clause 6 on general technical requirements.
What are the key requirements of SIST EN 50171:2022/oprA1:2026?
SIST EN 50171:2022/oprA1:2026 strengthens the technical rules for battery-backed safety supply, with a strong focus on continuity of supply, monitoring, EMC, and battery protection.
Load separation and continuity of supply
The CPS is intended only for essential safety equipment, and mixed safety loads are allowed only when one load does not reduce the availability of another. Clause 6.1 adds that, in battery mode, the CPS must keep emergency lighting supplied even if there is a first insulation failure in the battery circuit or luminaire circuit. In practice, the wiring and insulation design must tolerate a first fault without losing lighting.
Operating modes and switching behavior
Clause 4 covers changeover mode, mode without interruption, non-maintained changeover mode, and variants with additional control switching devices for central or partial load switching. The amendment replaces the graphics for these modes, so the document remains tied to the operating principles shown in the figures. Clause 6.5.4 also tightens one response requirement to activation within 5 s, which matters for switching and acceptance tests.
Battery protection, monitoring, and life
Clause 5.1 requires deep discharge protection, and Clause 6.7 refers to deep discharge indication. Clause 6.8.1 and 6.8.2 add battery charge/discharge current and a clearer ready-to-operate condition. Clause 6.13.2 sets a design life expectancy of at least 10 years at 20 °C for batteries used in CPS and LPS. In practice, users need battery selection, monitoring, and maintenance plans that fit long-life safety service.
EMC and UPS interface requirements
Clause 5.1 links immunity and emissions to the installation location. Immunity follows EN IEC 61000-6-2, while emissions depend on whether the location is residential, commercial and light-industrial, or industrial. If the CPS uses a UPS to feed the essential safety system, it also has to meet EN IEC 62040-1 and EN IEC 62040-2, with category requirements applied according to location. This matters when choosing equipment for hospitals, offices, public buildings, or industrial sites.
User information and test provisions
Clause 5.2 requires the user to specify the type and intended location of the battery. Clause 6.12.1 adds requirements for automatic test units with recording: if monitoring is periodic, the interval must be shorter than 5 min. This gives installers and maintenance teams a clear basis for status checks and records.
What terms does SIST EN 50171:2022/oprA1:2026 define?
- residential location - an area for domestic dwellings directly connected to the low-voltage public mains network.
- commercial location and light-industrial location - a non-residential location connected to the low-voltage public network, or through a dedicated DC source intended to interface with it.
- industrial location - a location with a separate power network supplied from a high- or medium-voltage transformer for the installation.
- CPS - central safety power supply systems, the central battery-backed supply arrangement covered by the document.
- UPS - uninterruptible power systems, used when a CPS relies on a UPS to feed the essential safety system.
- LPS - low power safety supply systems, which are also subject to the battery life requirement in Clause 6.13.2.
Who uses SIST EN 50171:2022/oprA1:2026?
SIST EN 50171:2022/oprA1:2026 is used by manufacturers, system integrators, designers, installers, and maintenance teams for emergency and life-safety power systems. It is also relevant to quality managers, buyers, and specifiers for buildings that use emergency escape lighting or other essential safety loads.
Typical applications include automatic fire extinguishing systems, paging and signalling safety systems, smoke extraction, carbon monoxide warning systems, and special safety installations in high-risk areas. The standard helps these users define the battery-backed supply, the operating mode, the monitoring arrangement, and the acceptance checks.
What changed in SIST EN 50171:2022/oprA1:2026 from the previous edition?
This amendment modifies EN 50171:2021. The changes stated in the document include:
- a wording change in the scope from “the interruption” to “a failure”
- updated normative references to EN IEC 62040-1 and EN IEC 61000-6-2, -6-3, -6-4, -6-8, and EN IEC 62040-2
- three added location definitions: residential, commercial and light-industrial, and industrial
- replacement graphics for the operating modes in Clause 4
- a new requirement for deep discharge protection
- revised EMC requirements by location
- added user information on battery type and intended location
- continuity during a first insulation failure in the battery or luminaire circuit
- UPS-related requirements for CPS
- activation within 5 s in one clause
- updated test and monitoring text, including automatic test unit monitoring intervals shorter than 5 min
- a 10-year battery life expectancy at 20 °C
Which standards are used with SIST EN 50171:2022/oprA1:2026?
- EN IEC 62040-1 - provides safety requirements for UPS when a CPS uses a UPS to feed the essential safety system.
- EN IEC 62040-2 - provides EMC requirements for the UPS used in that role.
- EN IEC 61000-6-2 - provides the immunity standard for industrial environments.
- EN IEC 61000-6-3 - provides the emission standard for residential locations.
- EN IEC 61000-6-4 - provides the emission standard for industrial environments.
- EN IEC 61000-6-8:2020 - provides the emission standard for professional equipment in commercial and light-industrial locations.
What does the SIST EN 50171:2022/oprA1:2026 document contain?
The document contains clause-by-clause amendments to the main standard, with updates to scope, references, definitions, operating-mode graphics, EMC rules, battery requirements, and verification wording. Clause 4 gives the schematic representations of the main operating modes, while Clause 6 collects the technical requirements for batteries, monitoring, deep discharge protection, and service life.
It also includes practical verification text for system status, test units, and compliance checks in both normal and emergency mode. For users, that means the document is meant to guide design, inspection, testing, and maintenance of central safety power supply systems rather than to describe the safety loads in general terms.
Relations
- Effective Date
- 15-Oct-2024
- Effective Date
- 15-Oct-2024
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Frequently Asked Questions
SIST EN 50171:2022/oprA1:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Central safety power supply systems". This standard covers: This document specifies the general requirements for central power supply systems for an independent energy supply to essential safety equipment. This standard covers systems that are permanently connected to AC supply voltages not exceeding 1 000 V and use batteries as an alternative power source. Central safety power supply systems are intended to ensure energy supply to emergency escape lighting in the event of normal supply failure and may be suitable for energizing other essential safety equipment, for example: – electric circuits of automatic fire extinguishing installations; – paging systems and signalling safety installations; – smoke extraction equipment; – carbon monoxide warning systems; – special safety installations related to specific buildings, e.g. high-risk areas. The power supply of CPS systems should be dedicated only to the essential safety equipment, and not for other type of loads such as general purpose IT or industrial systems etc. Combinations of the aforementioned safety equipment types are permitted together on the same central safety power supply system providing the availability for safety equipment loads is not impaired. A fault occurring in a circuit should not cause the interruption in any other circuit used to supply essential safety equipment. Schematic representations of typical central safety power supply equipment are depicted in Clause 4. Power supply systems for fire alarm equipment that are covered by EN 54 (series) are excluded.
This document specifies the general requirements for central power supply systems for an independent energy supply to essential safety equipment. This standard covers systems that are permanently connected to AC supply voltages not exceeding 1 000 V and use batteries as an alternative power source. Central safety power supply systems are intended to ensure energy supply to emergency escape lighting in the event of normal supply failure and may be suitable for energizing other essential safety equipment, for example: – electric circuits of automatic fire extinguishing installations; – paging systems and signalling safety installations; – smoke extraction equipment; – carbon monoxide warning systems; – special safety installations related to specific buildings, e.g. high-risk areas. The power supply of CPS systems should be dedicated only to the essential safety equipment, and not for other type of loads such as general purpose IT or industrial systems etc. Combinations of the aforementioned safety equipment types are permitted together on the same central safety power supply system providing the availability for safety equipment loads is not impaired. A fault occurring in a circuit should not cause the interruption in any other circuit used to supply essential safety equipment. Schematic representations of typical central safety power supply equipment are depicted in Clause 4. Power supply systems for fire alarm equipment that are covered by EN 54 (series) are excluded.
SIST EN 50171:2022/oprA1:2026 is classified under the following ICS (International Classification for Standards) categories: 29.200 - Rectifiers. Convertors. Stabilized power supply; 29.240 - Power transmission and distribution networks. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 50171:2022/oprA1:2026 has the following relationships with other standards: It is inter standard links to SIST EN 50171:2022, SIST EN 50171:2022/AC:2024. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN 50171:2022/oprA1:2026 is associated with the following European legislation: EU Directives/Regulations: 2014/30/EU, 2014/35/EU; Standardization Mandates: M/511, M/552. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
SIST EN 50171:2022/oprA1:2026 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-julij-2026
Centralni varnostni napajalni sistemi
Central safety power supply systems
Zentrale Sicherheitsstromversorgungssysteme
Systèmes d'alimentation de sécurité à source centrale
Ta slovenski standard je istoveten z: EN 50171:2021/prA1:2026
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME EUROPÉENNE PROJET
EN 50171:2021
EUROPÄISCHE NORM
EUROPEAN STANDARD
prA1
Juillet 2026
ICS 29.240 -
Version française
Systèmes d'alimentation de sécurité à source centrale
Zentrale Sicherheitsstromversorgungssysteme Central safety power supply systems
Ce projet d'amendement prA1, s'il est approuvé, modifiera la Norme Européenne EN 50171:2021; il est soumis aux membres du CENELEC
pour enquête.
Date limite du CENELEC: 2026-10-16.
Il a été établi par le CLC/TC 22X.
Si ce projet devient un amendement, les membres du CENELEC sont tenus de se soumettre au Règlement Intérieur du CEN/CENELEC,
qui définit les conditions dans lesquelles doit être attribué, sans modification, le statut de norme nationale à cet amendement.
Le présent projet d'amendement a été établi par le CENELEC en trois versions officielles (allemand, anglais, français).
Une version dans une autre langue faite par traduction sous la responsabilité d'un membre du CENELEC dans sa langue nationale, et
notifiée au CEN-CENELEC Management Centre, a le même statut que les versions officielles.
Les membres du CENELEC sont les comités électrotechniques nationaux des pays suivants: Allemagne, Autriche, Belgique, Bulgarie,
Chypre, Croatie, Danemark, Espagne, Estonie, Finlande, France, Grèce, Hongrie, Irlande, Islande, Italie, Lettonie, Lituanie, Luxembourg,
Malte, Norvège, Pays-Bas, Pologne, Portugal, République de Macédoine du Nord, République de Serbie, République Tchèque, Roumanie,
Royaume-Uni, Slovaquie, Slovénie, Suède, Suisse et Turquie.
Les destinataires du présent projet sont invités à présenter, avec leurs observations, notifications des droits de propriété dont ils auraient
éventuellement connaissance et à fournir une documentation explicative.
Avertissement: Le présent document n'est pas une Norme Européenne. Il est diffusé pour examen et observations. Il est susceptible de
modification sans préavis et ne doit pas être cité comme Norme Européenne.
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
European Committee for Electrotechnical Standardization
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Bruxelles
© 2026 CENELEC Tous droits d'exploitation sous quelque forme et de quelque manière que ce soit réservés dans le monde entier aux
membres du CENELEC.
Project: 80778 Réf. n° EN 50171:2021/prA1:2026 F
Contents Page
1 European foreword . 3
2 1 Modification to Clause 1, “Scope” . 4
3 2 Modification to Clause 2, “Normative references” . 4
4 3 Modification to Clause 3, “Terms and definitions” . 4
5 4 Modification to 4.2, “Changeover mode” . 5
6 5 Modification to 4.3, “Mode without interruption” . 6
7 6 Modification to 4.4, “Changeover mode with an additional control switching device for
8 central switching of the load” . 6
9 7 Modification to 4.5, “Changeover mode with an additional control switching device for
10 partial switching of the load “ . 6
11 8 Modification to 4.6, “Non-maintained changeover mode” . 7
12 9 Modification to 4.7, “Mode without interruption with an additional control switching device
13 for central switching of the load” . 7
14 10 Modification to 5.1, “Normal operating conditions and requirements for central safety
15 power supply systems” . 7
16 11 Modification to 5.2, “Requirements to be specified by the user” . 8
17 12 Modification to 6.1, “General requirements” . 8
18 13 Modification to 6.3.1, “Battery charges and rectifiers” . 8
19 14 Modification to 6.5.4 . 8
20 15 Modification to 6.6.8 . 8
21 16 Modification to 6.6.11 . 8
22 17 Modification to 6.7 “Deep discharge protection” . 8
23 18 Modification to 6.8.1 . 9
24 19 Modification to 6.8.2 . 9
25 20 Modification to 6.8.4 . 9
26 21 Modification to 6.12.1 . 9
27 22 Modification to 6.12.4 . 9
28 23 Modification to 6.13.2 . 9
29 24 Modification to 6.13.4 . 9
30 European foreword
31 This document (EN 50171:2021/prA1:2026) has been prepared by CLC/TC 22X “Power electronics”.
32 This document is currently submitted to the Enquiry.
33 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)
35 1 Modification to Clause 1, “Scope”
nd
36 In the 4th paragraph, 2 sentence, replace “the interruption” with “a failure”.
37 2 Modification to Clause 2, “Normative references”
38 Replace the references to EN 62040-1, EN 61000-6-2, EN 61000-6-3 and EN 61000-6-4 with the following,
39 respectively:
40 EN IEC 62040-1, Uninterruptible power systems (UPS) - Part 1: Safety requirements (IEC 62040-1)
41 EN IEC 61000-6-2, Electromagnetic compatibility (EMC) - Part 6-2: Generic standards - Immunity standard for
42 industrial environments (IEC 61000-6-2)
43 EN IEC 61000-6-3, Electromagnetic compatibility (EMC) - Part 6-3: Generic standards - Emission standard for
44 equipment in residential locations (IEC 61000-6-3)
45 EN IEC 61000-6-4, Electromagnetic compatibility (EMC) - Part 6-4: Generic standards - Emission standard for
46 industrial environments (IEC 61000-6-4)
47 Add the following references:
48 EN IEC 61000-6-8:2020, Electromagnetic compatibility (EMC) - Part 6-8: Generic standards - Emission
49 standard for professional equipment in commercial and light-industrial locations
50 EN IEC 62040-2, Uninterruptible power systems (UPS) - Part 2: Electromagnetic compatibility (EMC)
51 requirements
52 3 Modification to Clause 3, “Terms and definitions”
53 Add the 3 following definitions:
54 3.24
55 residential location
56 area of land designated for domestic dwellings where the mains pow
...