oSIST prEN IEC 60335-2-73:2026
(Main)Household and similar electrical appliances - Safety - Part 2-73: Particular requirements for fixed immersion heaters
- Abstract
This European standard deals with the safety of electric thermal-storage room heaters intended to heat the room in which they are located, their rated voltage being not more than 250 V for single phase and 480 V for other appliances.
- Status
- Not Published
- Public Enquiry End Date
- 30-Oct-2026
- Technical Committee
- VGA - Safety of household and similar electrical appliances
- Current Stage
- 4020 - Public enquire (PE) (Adopted Project)
- Start Date
- 04-Sep-2026
- Due Date
- 22-Jan-2027
oSIST prEN IEC 60335-2-73:2026 is the SIST version of draft European Standard prEN IEC 60335-2-73, based on IEC 60335-2-73:2024. It specifies safety requirements for fixed electric immersion heaters for household and similar purposes, including heaters installed in water tanks open to the atmosphere and some boiler applications. It is written for manufacturers, test laboratories, certification bodies, installers, and anyone checking the safety design and documentation of these appliances.
What does oSIST prEN IEC 60335-2-73:2026 specify?
oSIST prEN IEC 60335-2-73:2026 specifies particular safety requirements for fixed immersion heaters and is intended to be used together with IEC 60335-1. The document is a Part 2 standard, so it supplements and modifies the general requirements of Part 1 for this product type.
The scope covers fixed electric immersion heaters for household and similar purposes, with rated voltage not more than 250 V for single-phase appliances and 480 V for other appliances, including DC supplied appliances. It also includes immersion heaters up to 25 kW for use as an alternative heat source in central heating boilers.
The document excludes appliances for industrial purposes, appliances used in special environments such as corrosive or explosive atmospheres, and heating elements already covered by other IEC 60335 Part 2 standards such as liquid heaters, storage water heaters, instantaneous water heaters, aquarium heaters, portable immersion heaters and engine preheaters.
The structure follows the IEC 60335 series with clauses 1 to 32, plus annexes and a bibliography. The annexes of Part 1 apply.
What are the key requirements of oSIST prEN IEC 60335-2-73:2026?
oSIST prEN IEC 60335-2-73:2026 focuses on installation safety, temperature rise, abnormal operation, construction, and earthing. In practice, it tells the manufacturer what the appliance must be marked as, how it is tested, and what safety features must be built in.
Scope and test basis
Clause 1 limits the appliance to installation in a water tank open to the atmosphere and defines normal use around water below boiling point. Clause 3 modifies the meaning of normal operation so the appliance is tested after installation in the smallest specified tank, thermally insulated and filled with water. That matters because the test setup must match the smallest approved installation.
Classification, marking and instructions
Clause 6 requires immersion heaters to be class I, class II or class III. Clause 7 requires multiple-supply appliances to show the rated power input for each supply circuit and to carry the warning substance “Do not cover”.
Clause 7 also requires installation instructions to state the tank type and dimensions, the heater position in the tank, that the tank must contain water before first switch-on, and that the heater is only for systems where the heating element is always below water level when applicable. That is the information installers need to avoid dry running and incorrect mounting.
Heating and surface temperature
Clause 11 adds a temperature probe and surface-temperature limits for specified accessible surfaces. Table 101 gives the maximum rises for bare metal, coated metal, glass and ceramic, and plastic surfaces under normal operation. In practice, this means the designer has to control accessible surface temperatures and the test lab has a defined probe and contact method.
Clause 11.7 limits the heating test to 24 hours if a thermal control operates. Clause 11.8 requires continuous monitoring of temperature rise during the test.
Abnormal operation and protection features
Clause 19 requires testing with the tank empty, with any thermal control used in Clause 11 short-circuited. If more than one thermal control operates in Clause 11, they are short-circuited in turn. A separate Clause 19 test covers operation with water at least 10 mm above the highest point of the heating element, or the highest permitted level.
Clause 24 requires thermal cut-outs used for Clause 19 compliance to be non-self-resetting and independent of the thermostat. This is a direct design requirement for overtemperature protection.
Construction and earthing
Clause 22 requires a seal or other means to prevent leakage from the tank after installation, and it limits rotation of the terminal compartment to no more than 180° relative to the fixed part. Clause 27 requires metal parts of class I immersion heaters that are in contact with water to be permanently connected to the earthing terminal. That affects both mechanical layout and protective bonding.
What terms does oSIST prEN IEC 60335-2-73:2026 define?
- Normal operation - operation after installation in the smallest specified tank, with the tank thermally insulated and filled with water.
- Thermal control - the control device that operates during heating tests and may be short-circuited in abnormal-operation testing.
- Thermal cut-out - a protection device used for Clause 19 compliance that must not be self-resetting and must work independently of the thermostat.
- Class I, class II, class III - the document allows immersion heaters to be built in any of these protection classes, so the chosen class affects insulation and earthing design.
Who uses oSIST prEN IEC 60335-2-73:2026?
oSIST prEN IEC 60335-2-73:2026 is used by manufacturers of fixed immersion heaters, design engineers, and safety test laboratories. It is also used by certification bodies and quality teams that verify product marking, installation instructions, temperature rise, leakage protection, and earthing.
Installers and service personnel use it indirectly because the standard specifies the tank type, water level, heater position, and the “Do not cover” warning. Buyers and compliance managers in household heating and water-heating supply chains use it to check whether a product is designed for the right application.
What changed in oSIST prEN IEC 60335-2-73:2026 from the previous edition?
This edition is a technical revision that cancels and replaces the second edition and its amendments. The stated changes are:
- alignment with IEC 60335-1:2020
- conversion of some notes into normative text in Clause 1 and Clause 19.2
- addition of external accessible surface temperatures in Clause 11
The European foreword also states that this draft will supersede EN 60335-2-73:2003 and its amendments and corrigenda.
Which standards are used with oSIST prEN IEC 60335-2-73:2026?
- IEC 60335-1 - the general safety standard that Part 2-73 supplements and modifies.
- IEC 60584-1 - gives thermocouple EMF specifications and tolerances for the surface-temperature measuring probe.
- prEN IEC 60335-2-73:2026/prAA:2026 - the companion draft amendment with which this document is read.
- IEC 60335-2-15, IEC 60335-2-21, IEC 60335-2-35, IEC 60335-2-55, IEC 60335-2-74 - related Part 2 standards cited in the bibliography for comparable heating applications.
- ISO 13732-1 - provides methods for assessing human response to hot surfaces, relevant to surface-temperature evaluation.
What does the oSIST prEN IEC 60335-2-73:2026 document contain?
The document contains the usual Part 2 safety structure: scope, normative references, terms and definitions, general requirements, test conditions, classification, marking, access to live parts, power input, heating, moisture resistance, abnormal operation, mechanical and construction requirements, earthing, and other safety clauses. It also includes Table 101 for surface-temperature limits and Figure 101 for the probe used to measure those temperatures.
For test labs, the most useful parts are the modified heating tests, the abnormal-operation tests, and the construction checks in Clauses 22, 24 and 27. For manufacturers, the document shows what must appear in the instructions and how the heater must be built so that installation and safety testing are consistent.
Relations
- Effective Date
- 10-Sep-2024
- Effective Date
- 30-Jul-2024
- Effective Date
- 30-Jul-2024
- Effective Date
- 30-Jul-2024
- Effective Date
- 30-Jul-2024
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Frequently Asked Questions
oSIST prEN IEC 60335-2-73:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Household and similar electrical appliances - Safety - Part 2-73: Particular requirements for fixed immersion heaters". This standard covers: This European standard deals with the safety of electric thermal-storage room heaters intended to heat the room in which they are located, their rated voltage being not more than 250 V for single phase and 480 V for other appliances.
This European standard deals with the safety of electric thermal-storage room heaters intended to heat the room in which they are located, their rated voltage being not more than 250 V for single phase and 480 V for other appliances.
oSIST prEN IEC 60335-2-73:2026 is classified under the following ICS (International Classification for Standards) categories: 13.120 - Domestic safety; 91.140.65 - Water heating equipment. The ICS classification helps identify the subject area and facilitates finding related standards.
oSIST prEN IEC 60335-2-73:2026 has the following relationships with other standards: It is inter standard links to oSIST prEN IEC 60335-2-73:2026/oprAA:2026, SIST EN 60335-2-73:2003, SIST EN 60335-2-73:2003/A1:2006, SIST EN 60335-2-73:2003/A11:2021, SIST EN 60335-2-73:2003/A2:2010. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
oSIST prEN IEC 60335-2-73:2026 is associated with the following European legislation: EU Directives/Regulations: 2014/35/EU, 2014/53/EU, 2014/55/EU; Standardization Mandates: M/511, M/536, M/585. 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.
oSIST prEN IEC 60335-2-73:2026 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-oktober-2026
Gospodinjski in podobni električni aparati - Varnost - 2-73. del: Posebne zahteve
za pritrjene potopne grelnike
Household and similar electrical appliances - Safety - Part 2-73: Particular requirements
for fixed immersion heaters
Sicherheit elektrischer Geräte für den Hausgebrauch und ähnliche Zwecke - Teil 2-73:
Besondere Anforderungen für ortsfeste Heizeinsätze
Appareils électrodomestiques et analogues - Sécurité - Partie 2-73: Règles particulières
pour les thermoplongeurs installés à poste fixe
Ta slovenski standard je istoveten z: prEN IEC 60335-2-73:2026
ICS:
13.120 Varnost na domu Domestic safety
91.140.65 Oprema za ogrevanje vode Water heating equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD DRAFT
prEN IEC 60335-2-73
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2026
ICS 91.140.65 Will supersede EN 60335-2-73:2003; EN 60335-2-
73:2003/A1:2006; EN 60335-2-73:2003/A2:2009; EN
60335-2-73:2003/A11:2021
English Version
Household and similar electrical appliances - Safety - Part 2-73:
Particular requirements for fixed immersion heaters
(IEC 60335-2-73:2024)
Appareils électrodomestiques et analogues - Sécurité - Sicherheit elektrischer Geräte für den Hausgebrauch und
Partie 2-73: Règles particulières pour les thermoplongeurs ähnliche Zwecke - Teil 2-73: Besondere Anforderungen für
installés à poste fixe ortsfeste Heizeinsätze
(IEC 60335-2-73:2024) (IEC 60335-2-73:2024)
This draft European Standard is submitted to CENELEC members for enquiry.
Deadline for CENELEC: 2026-11-06.
The text of this draft consists of the text of IEC 60335-2-73:2024.
If this draft becomes a European Standard, CENELEC 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 CENELEC in three official versions (English, French, German).
A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to
the CEN-CENELEC Management Centre has the same status as the official versions.
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 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 Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Project: 80416 Ref. No. prEN IEC 60335-2-73:2026 E
European foreword
This document (prEN IEC 60335-2-73:2026) consists of the text of document IEC 60335-2-73:2024,
prepared by IEC/TC 61 "Safety of household and similar electrical appliances".
This document is currently submitted to the Enquiry.
The following dates are proposed:
• latest date by which the existence of this document (doa) dav + 6 months
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 withdrawn (to be confirmed or
modified when voting)
This document will supersede EN 60335-2-73:2003 and all of its amendments and corrigenda (if any).
This document is read in conjunction with prEN IEC 60335-2-73:2026/prAA:2026.
IEC 60335-2-73 ®
Edition 3.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical appliances – Safety –
Part 2-73: Particular requirements for fixed immersion heaters
Appareils électrodomestiques et analogues – Sécurité –
Partie 2-73: Règles particulières pour les thermoplongeurs installés à poste fixe
IEC 60335-2-73:2024-03(en-fr)
IEC 60335-2-73 ®
Edition 3.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical appliances – Safety –
Part 2-73: Particular requirements for fixed immersion heaters
Appareils électrodomestiques et analogues – Sécurité –
Partie 2-73: Règles particulières pour les thermoplongeurs installés à poste fixe
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 91.140.65 ISBN 978-2-8322-8459-9
– 2 – IEC 60335-2-73:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 General requirement . 8
5 General conditions for the tests . 8
6 Classification . 8
7 Marking and instructions . 9
8 Protection against access to live parts . 9
9 Starting of motor-operated appliances . 9
10 Power input and current . 9
11 Heating . 9
12 Charging of metal-ion batteries . 10
13 Leakage current and electric strength at operating temperature . 10
14 Transient overvoltages . 10
15 Moisture resistance . 10
16 Leakage current and electric strength . 11
17 Overload protection of transformers and associated circuits . 11
18 Endurance . 11
19 Abnormal operation . 11
20 Stability and mechanical hazards . 11
21 Mechanical strength . 11
22 Construction . 11
23 Internal wiring . 12
24 Components . 12
25 Supply connection and external flexible cords . 12
26 Terminals for external conductors . 12
27 Provision for earthing . 12
28 Screws and connections . 12
29 Clearances, creepage distances and solid insulation . 12
30 Resistance to heat and fire . 12
31 Resistance to rusting . 13
32 Radiation, toxicity and similar hazards . 13
Annexes . 14
Bibliography . 15
Figure 101 – Probe for measuring surface temperatures . 13
Table 101 – Maximum temperature rises for specified external accessible surfaces
under normal operating conditions . 10
IEC 60335-2-73:2024 © IEC 2024 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES –
SAFETY –
Part 2-73: Particular requirements for fixed immersion heaters
FOREWORD
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC 60335-2-73 has been prepared by IEC technical committee 61: Safety of household and
similar electrical appliances. It is an International Standard.
This third edition cancels and replaces the second edition published in 2002, Amendment 1:
2006 and Amendment 2: 2009. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the text has been aligned with IEC 60335-1:2020;
b) some notes have been converted to normative text (Clause 1, 19.2);
c) addition of external accessible surface temperatures (Clause 11).
– 4 – IEC 60335-2-73:2024 © IEC 2024
The text of this International Standard is based on the following documents:
Draft Report on voting
61/6954/CDV 61/7055A/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of the IEC 60335 series, under the general title: Household and similar
electrical appliances – Safety, can be found on the IEC website.
This part 2 is to be used in conjunction with the latest edition of IEC 60335-1 and its
amendments unless that edition precludes it; in that case, the latest edition that does not
preclude it is used. It was established on the basis of the sixth edition (2020) of that standard.
NOTE 1 When "Part 1" is mentioned in this standard, it refers to IEC 60335-1.
This part 2 supplements or modifies the corresponding clauses in IEC 60335-1, so as to convert
that publication into the IEC standard: Particular requirements for fixed immersion heaters.
When a particular subclause of Part 1 is not mentioned in this part 2, that subclause applies as
far as is reasonable. When this standard s
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