IEC 60335-2-51:2019

Household and similar electrical appliances - Safety - Part 2-51: Particular requirements for stationary circulation pumps for heating and service water installations

IEC 60335-2-51:2019 deals with the safety of electric stationary circulation pumps for household and similar purposes intended for use in heating systems or in service water systems, their rated voltage being not more than 250 V for single-phase appliances and 480 V for other appliances. The hydraulic and electrical parts of the pump can be in the same enclosure, so that the water flows through the motor and serves as a coolant, or they can be separated. Appliances not intended for normal household use, but that nevertheless may be a source of danger to the public, such as appliances intended to be used by laymen in shops, in light industry and on farms, are within the scope of this standard. As far as is practicable, this standard deals with the common hazards presented by appliances that are encountered by all persons in and around the home. However, in general, it does not take into account
– persons (including children) whose physical, sensory or mental capabilities; or lack of experience and knowledge prevents them from using the appliance safely without supervision or instruction;
– children playing with the appliance.
Attention is drawn to the fact that:
– for appliances intended to be used in vehicles or on board ships or aircraft, additional requirements can be necessary;
– in many countries additional requirements are specified by the national health authorities, the national authorities responsible for the protection of labour and similar authorities.
This standard does not apply to:
– pumps for circulating liquids other than water;
– pumps, other than circulation pumps (IEC 60335-2-41);
– circulation pumps intended exclusively for industrial purposes;
– circulation pumps intended to be used in locations where special conditions prevail, such as the presence of a corrosive or explosive atmosphere (dust, vapour, or gas).
This fourth edition cancels and replaces the third edition published in 2002, Amendment 1:2008 and Amendment 2:2011. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
– some instructions are no longer required (7.12);
– converted some notes to normative text (7.12.1, 11.3, 11.8);
– new instructions for installation of thermal insulation (7.12.1);
– the leakage current value is modified (Clause A.2).
This part 2 is to be used in conjunction with the latest edition of IEC 60335-1 and its amendments. It was established on the basis of the fifth edition (2010) of that standard.

Appareils électrodomestiques et analogues - Sécurité - Partie 2-51: Exigences particulières pour les pompes de circulation fixes pour installations de chauffage et de distribution d'eau

L'IEC 60335-2-51:2019 traite de la sécurité des pompes de circulation fixes électriques pour usages domestiques et analogues, destinées à être utilisées dans des installations de chauffage ou de distribution d'eau, dont la tension assignée n'est pas supérieure à 250 V pour les appareils monophasés et à 480 V pour les autres appareils. Les parties hydrauliques et électriques de la pompe peuvent être dans la même enveloppe, de sorte que l'eau s'écoule à travers le moteur et serve de liquide de refroidissement, ou elles peuvent être séparées. Les appareils non destinés à un usage domestique normal, mais qui peuvent néanmoins constituer une source de danger pour le public, tels que les appareils destinés à être utilisés par des usagers non avertis dans des magasins, chez des artisans et dans des fermes, sont compris dans le domaine d'application de la présente norme. Dans la mesure du possible, la présente norme traite des risques ordinaires présentés par les appareils, encourus par tous les individus à l’intérieur et autour de l'habitation. Cependant, cette norme ne tient pas compte en général:
– des personnes (y compris des enfants) dontles capacités physiques, sensorielles ou mentales; ou le manque d’expérience et de connaissance les empêchent d’utiliser l’appareil en toute sécurité sans surveillance ou instruction;
– de l’utilisation de l’appareil comme jouet par des enfants.
L'attention est attirée sur le fait que:
– pour les appareils destinés à être utilisés dans des véhicules ou à bord de navires ou d'avions, des exigences supplémentaires peuvent être nécessaires;
– dans de nombreux pays, des exigences supplémentaires sont spécifiées par les organismes nationaux de la santé, par les organismes nationaux responsables de la protection des travailleurs et par des organismes similaires.
La présente norme ne s'applique pas:
– aux pompes destinées à la circulation de liquides autres que l'eau;
– aux pompes autres que les pompes de circulation (IEC 60335-2-41);
– aux pompes de circulation destinées exclusivement aux usages industriels;
– aux pompes de circulation destinées à être utilisées dans des locaux présentant des conditions particulières telles que la présence d'une atmosphère corrosive ou explosive (poussières, vapeur ou gaz).
Cette quatrième édition annule et remplace la troisième édition parue en 2002, l'Amendement 1:2008 et l'Amendement 2:2011. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
– certaines instructions ne sont plus exigées (7.12);
– certaines notes ont été converties en texte normatif (7.12.1, 11.3, 11.8);
– nouvelles instructions d'installation de l'isolant thermique (7.12.1);
– la valeur du courant de fuite a été modifiée (Article A.2).
La présente partie 2 doit être utilisée conjointement avec la dernière édition de l'IEC 60335-1 et ses amendements. Elle a été établie sur la base de la cinquième édition (2010) de cette norme.

General Information

• Status: Published
• Publication Date: 14-Apr-2019
• ICS: 23.080 - Pumps
• ICS: 91.140.10 - Central heating systems
• Technical Committee: TC 61 - Safety of household and similar electrical appliances
• Drafting Committee: MT 37 - TC 61/MT 37
• Current Stage: DELPUB - Deleted Publication
• Start Date: 14-Dec-2023
• Completion Date: 30-Nov-2021

Relations

• Revises: IEC 60335-2-51:2002 - Household and similar electrical appliances - Safety - Part 2-51: Particular requirements for stationary circulation pumps for heating and service water installations
• Effective Date: 05-Sep-2023
• Revises: IEC 60335-2-51:2002/AMD1:2008 - Amendment 1 - Household and similar electrical appliances - Safety - Part 2-51: Particular requirements for stationary circulation pumps for heating and service water installations
• Effective Date: 05-Sep-2023
• Revised: IEC 60335-2-51:2023 - Household and similar electrical appliances - Safety - Part 2-51: Particular requirements for stationary circulation pumps for heating and service water installations
• Effective Date: 05-Sep-2023
• Revises: IEC 60335-2-51:2002/AMD2:2011 - Amendment 2 - Household and similar electrical appliances - Safety - Part 2-51: Particular requirements for stationary circulation pumps for heating and service water installations
• Effective Date: 05-Sep-2023

Overview

IEC 60335-2-51:2019 is the 4th-edition IEC safety standard for stationary circulation pumps used in household and similar heating systems and service (domestic hot) water installations. It sets particular safety requirements for electric circulation pumps with rated power input up to 300 W and rated voltages up to 250 V (single‑phase) or 480 V (other). This part is intended to be used together with IEC 60335-1 (the general household appliance safety standard) and constitutes a technical revision of the previous editions.

Key topics and technical requirements

The standard supplements and modifies Part 1 requirements to address pump‑specific hazards. Major topics covered include:

• Scope and applicability - household and similar use, also appliances used by laymen in shops, light industry and farms; explicit exclusions (e.g., pumps for liquids other than water, pumps exclusively for industrial use, pumps for corrosive/explosive atmospheres).
• Electrical safety - protection against access to live parts, leakage current limits, electric strength at operating temperature, transient overvoltages, supply connection and earthing provisions.
• Thermal and fire safety - heating limits, temperature classification of pump parts, requirements for thermal insulation and new instructions for insulation installation.
• Mechanical and functional safety - stability, mechanical strength, internal wiring, component and terminal requirements, resistance to rusting and moisture.
• Reliability and abnormal conditions - endurance tests, abnormal operation tests, overload protection, moisture resistance and routine tests.
• Updates in the 2019 edition - conversion of certain notes to normative text, removal of some instructions, new installation instructions for thermal insulation, and modification of leakage current value.

Practical applications - who uses this standard

IEC 60335-2-51 is used by:

• Pump manufacturers and product designers to design and certify compliant circulation pumps for domestic heating and hot‑water systems.
• Test laboratories and certification bodies for type testing and conformity assessment in line with IEC 60335 series requirements.
• Regulatory authorities and compliance engineers when setting national safety rules or evaluating market access.
• Installers and system integrators to understand safe installation, earthing and thermal insulation requirements referenced by manufacturers.

Related standards

• IEC 60335-1 - General requirements for household appliance safety (mandatory companion standard).
• IEC 60335 series - Other Part 2 standards (e.g., IEC 60335-2-41 for other pump types).
• IEC 60364 and product‑safety wiring rules - referenced for compatibility with fixed wiring.
• Relevant national regulations - health, labour and electrical safety authorities may impose additional requirements.

Keywords: IEC 60335-2-51, stationary circulation pumps, safety standard, heating systems, service water installations, leakage current, thermal insulation, IEC 60335-1, pump certification.

Standards Content (Sample)

IEC 60335-2-51 ®
Edition 4.0 2019-04
REDLINE VERSION
INTERNATIONAL
STANDARD
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inside
Household and similar electrical appliances – Safety –
Part 2-51: Particular requirements for stationary circulation pumps for heating
and service water installations

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IEC 60335-2-51 ®
Edition 4.0 2019-04
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Household and similar electrical appliances – Safety –

Part 2-51: Particular requirements for stationary circulation pumps for heating

and service water installations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 23.080; 91.140.10 ISBN 978-2-8322-6851-3

– 2 – IEC 60335-2-51:2019 RLV © 2019

CONTENTS
FOREWORD . 3

INTRODUCTION . 2

1 Scope . 7

2 Normative references . 7

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 . 10
9 Starting of motor-operated appliances . 10
10 Power input and current . 10
11 Heating . 10
12 Void . 10
13 Leakage current and electric strength at operating temperature . 10
14 Transient overvoltages . 11
15 Moisture resistance . 11
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 . 12
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
Annex A (informative) Routine tests . 14
Bibliography . 15

Table 101 – Temperature classification of circulation pumps . 9

– 4 – IEC 60335-2-51:2019 RLV © 2019

International Standard IEC 60335-2-51 has been prepared by IEC technical committee 61:

Safety of household and similar electrical appliances.

This fourth edition cancels and replaces the third edition published in 2002,

Amendment 1:2008 and Amendment 2:2011. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
– some instructions are no longer required (7.12);

– converted some notes to normative text (7.12.1, 11.3, 11.8);

– new instructions for installation of thermal insulation (7.12.1);
– the leakage current value is modified (Clause A.2).
The text of this International Standard is based on the following documents:
FDIS Report on voting
61/5785/FDIS 61/5802/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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. It was established on the basis of the fifth edition (2010) 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: Safety requirements for electric stationary
circulation pumps for heating and service water installations.
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 states “addition”, “modification” or “replacement”,
the relevant text in Part 1 is to be adapted accordingly.

NOTE 2 The following numbering system is used:
– subclauses, tables and figures that are numbered starting from 101 are additional to those in Part 1;
– unless notes are in a new subclause or involve notes in Part 1, they are numbered starting from 101, including
those in a replaced clause or subclause;
– additional annexes are lettered AA, BB, etc.
NOTE 3 The following print types are used:
– requirements: in roman type;
– test specifications: in italic type;
notes: in small roman type.
–
Words in bold in the text are defined in Clause 3. When a definition concerns an adjective, the adjective and the
associated noun are also in bold.

– 4 – IEC 60335-2-51:2019 RLV © 2019

International Standard IEC 60335-2-51 has been prepared by IEC technical committee 61:

Safety of household and similar electrical appliances.

This fourth edition cancels and replaces the third edition published in 2002,

Amendment 1:2008 and Amendment 2:2011. This edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
– some instructions are no longer required (7.12);

– converted some notes to normative text (7.12.1, 11.3, 11.8);

– new instructions for installation of thermal insulation (7.12.1);
– the leakage current value is modified (Clause A.2).
The text of this International Standard is based on the following documents:
FDIS Report on voting
61/5785/FDIS 61/5802/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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. It was established on the basis of the fifth edition (2010) 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: Safety requirements for electric stationary
circulation pumps for heating and service water installations.
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 states “addition”, “modification” or “replacement”,
the relevant text in Part 1 is to be adapted accordingly.

NOTE 2 The following numbering system is used:
– subclauses, tables and figures that are numbered starting from 101 are additional to those in Part 1;
– unless notes are in a new subclause or involve notes in Part 1, they are numbered starting from 101, including
those in a replaced clause or subclause;
– additional annexes are lettered AA, BB, etc.
NOTE 3 The following print types are used:
– requirements: in roman type;
– test specifications: in italic type;
– notes: in small roman type.
Words in bold in the text are defined in Clause 3. When a definition concerns an adjective, the adjective and the
associated noun are also in bold.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or

• amended.
NOTE 4 The attention of National Committees is drawn to the fact that equipment manufacturers and testing

organizations may need a transitional period following publication of a new, amended or revised IEC publication in

which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests.
It is the recommendation of the committee that the content of this publication be adopted for implementation
nationally not earlier than 12 months or later than 36 months from the date of publication.

IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

– 6 – IEC 60335-2-51:2019 RLV © 2019

INTRODUCTION
It has been assumed in the drafting of this International Standard that the execution of its

provisions is entrusted to appropriately qualified and experienced persons.

This standard recognizes the internationally accepted level of protection against hazards such

as electrical, mechanical, thermal, fire and radiation of appliances when operated as in

normal use taking into account the manufacturer's instructions. It also covers abnormal

situations that can be expected in practice and takes into account the way in which

electromagnetic phenomena can affect the safe operation of appliances.

This standard takes into account the requirements of IEC 60364 as far as possible so that
there is compatibility with the wiring rules when the appliance is connected to the supply
mains. However, national wiring rules may differ.
If an appliance within the scope of this standard also incorporates functions that are covered
by another part 2 of IEC 60335, the relevant part 2 is applied to each function separately, as
far as is reasonable. If applicable, the influence of one function on the other is taken into
account.
When a part 2 standard does not include additional requirements to cover hazards dealt with
in Part 1, Part 1 applies.
NOTE 1 This means that the technical committees responsible for the part 2 standards have determined that it is
not necessary to specify particular requirements for the appliance in question over and above the general
requirements.
This standard is a product family standard dealing with the safety of appliances and takes
precedence over horizontal and generic standards covering the same subject.
NOTE 2 Horizontal and generic standards covering a hazard are not applicable since they have been taken into
consideration when developing the general and particular requirements for the IEC 60335 series of standards. For
example, in the case of temperature requirements for surfaces on many appliances, generic standards, such as
ISO 13732-1 for hot surfaces, are not applicable in addition to Part 1 or part 2 standards.
An appliance that complies with the text of this standard will not necessarily be considered to
comply with the safety principles of the standard if, when examined and tested, it is found to
have other features that impair the level of safety covered by these requirements.
An appliance employing materials or having forms of construction differing from those detailed
in the requirements of this standard may be examined and tested according to the intent of
the requirements and, if found to be substantially equivalent, may be considered to comply
with the standard.
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES – SAFETY –

Part 2-51: Particular requirements for stationary circulation pumps
for heating and service water installations

1 Scope
This clause of Part 1 is replaced by the following.
This International Standard deals with the safety of electric stationary circulation pumps for
household and similar purposes intended for use in heating systems or in service water
systems, having a rated power input not exceeding 300 W, their rated voltage being not
more than 250 V for single-phase appliances and 480 V for other appliances.
NOTE 101 The hydraulic and electrical parts of the pump may can be in the same enclosure, so that the water
flows through the motor and serves as a coolant, or they may can be separated.
Appliances not intended for normal household use, but that nevertheless may be a source of
danger to the public, such as appliances intended to be used by laymen in shops, in light
industry and on farms, are within the scope of this standard.
As far as is practicable, this standard deals with the common hazards presented by
appliances that are encountered by all persons in and around the home. However, in general,
it does not take into account
– the use of appliances by young children or infirm persons without supervision;
– playing with the appliance by young children.
– persons (including children) whose
• physical, sensory or mental capabilities; or
• lack of experience and knowledge
prevents them from using the appliance safely without supervision or instruction;
– children playing with the appliance.
NOTE 102 Attention is drawn to the fact that
– for appliances intended to be used in vehicles or on board ships or aircraft, additional requirements may can
be necessary;
– in many countries additional requirements are specified by the national health authorities, the national
authorities responsible for the protection of labour and similar authorities.
NOTE 103 This standard does not apply to
– pumps for circulating liquids other than water;
– pumps, other than circulation pumps (IEC 60335-2-41);
– circulation pumps intended exclusively for industrial purposes;
– circulation pumps intended to be used in locations where special conditions prevail, such as the presence of a
corrosive or explosive atmosphere (dust, vapour, or gas).
2 Normative references
This clause of Part 1 is applicable.

– 8 – IEC 60335-2-51:2019 RLV © 2019

3 Terms and definitions
This clause of Part 1 is applicable except as follows.

3.1 Definitions relating to physical characteristics

Replacement:
3.1.9
normal operation
operation of the circulation pump with the water pressure and flow rate adjusted within their

specified limits, so that the highest power input is attained
4 General requirement
This clause of Part 1 is applicable.
5 General conditions for the tests
This clause of Part 1 is applicable except as follows.
5.7 Addition:
The water temperature at the inlet is maintained between 0 °C and –5 °C of the value
corresponding to the TF class of the pump.
For circulation pumps intended to be located within the enclosure of a boiler, the tests of
Clauses 10, 11 and 13 are carried out at an ambient temperature of 55 °C or at the
temperature specified in the instructions, whichever is higher.
5.101 Circulation pumps having a three-phase motor that does not incorporate a protective
device are installed with an appropriate device, in accordance with the instructions.
6 Classification
This clause of Part 1 is applicable except as follows.
6.1 Modification:
Circulation pumps shall be class I, class II or class III.
6.2 Addition:
Circulation pumps shall be at least IPX2.
6.101 Circulation pumps shall be of one of the classes shown in Table 101.

Table 101 – Temperature classification of circulation pumps

Class Maximum temperature of
the circulating water
°C
TF  60 60
TF  95 95
TF 110 110
Compliance is checked by inspection.
7 Marking and instructions
This clause of Part 1 is applicable except as follows.
7.1 Addition:
Circulation pumps shall be marked with
– the TF class;
– the direction of the water flow;
– the direction of rotation (for pumps having three-phase motors);
– the rated current (for pumps having three-phase motors if a protective device has to be
installed in the fixed wiring).
7.12 Modification:
The instruction concerning persons (including children) with reduced physical, sensory or
mental capabilities, or lack of experience and knowledge is not applicable.
The instruction regarding supervision of children is not applicable.
7.12.1 Addition:
The installation instructions shall state the substance of the following:
– the maximum flow rate or total head;

– the maximum ambient temperature at which the pump is to be used;
– the maximum system pressure, which shall not be less than:
NOTE 101 The maximum system pressure is to be not less than
• 0,6 MPa for pumps for heating systems;
• 1,0 MPa for pumps for service water systems;
– the intended orientation of the pump;
– a protective device is to be installed in the fixed wiring and its characteristics are to be
specified (for pumps having a three-phase motor not incorporating a protective device).
– for the thermal insulation of circulation pumps in heating systems, only the supplied kit or
a kit made available by the manufacturer shall be used. It shall be ensured that the drain
openings of the motor are not sealed after installation of the thermal insulation.

– 10 – IEC 60335-2-51:2019 RLV © 2019

8 Protection against access to live parts

This clause of Part 1 is applicable.

9 Starting of motor-operated appliances

This clause of Part 1 is not applicable.

10 Power input and current
This clause of Part 1 is applicable.
11 Heating
This clause of Part 1 is applicable except as follows.
11.2 Addition:
Circulation pumps that are only fixed by the water pipes are positioned against a vertical
support one wall of the test corner and away from the other.
11.3 Addition:
NOTE 101 The temperatures t and t , referred to in note 4, are the ambient temperatures of
1 2
the environment in which the pump is installed, for instance inside the enclosure of a boiler.
11.7 Replacement:
Circulation pumps are operated until steady conditions are established.
11.8 Addition:
The temperature rise limits of pumps located within the enclosure of a boiler are reduced by
the difference between the ambient temperature at which the test is carried out and 25 °C.
The temperature rise of the external enclosure is not measured.

For circulation pumps in which water flows through the motor, the temperature rise limits for
windings are increased by 5 K. The temperature rise limits are increased further by
– 5 K, if the winding insulation is class 130 (B);
– 10 K, if the winding insulation is class 155 (F) or 180 (H).
NOTE 101 For circulation pumps in which water flows through the motor, the increase of 5 K
a
allowed by footnote to Table 3 does not apply.
12 Void
13 Leakage current and electric strength at operating temperature
This clause of Part 1 is applicable.

14 Transient overvoltages
This clause of Part 1 is applicable.

15 Moisture resistance
This clause of Part 1 is applicable.

16 Leakage current and electric strength

This clause of Part 1 is applicable.
17 Overload protection of transformers and associated circuits
This clause of Part 1 is applicable.
18 Endurance
This clause of Part 1 is not applicable.
19 Abnormal operation
This clause of Part 1 is applicable except as follows.
19.1 Addition:
Circulation pumps are also subjected to the test of 19.101.
19.7 Addition:
The test is carried out with the water flow stopped or reduced to 5 l/min, whichever is more
unfavourable.
19.101 Circulation pumps are supplied at rated voltage and operated at approximately half
the maximum system pressure for 5 min, after which the water is drained off and the operation
continued for 7 h. The system is replenished with water and the pump operated again for

5 min at approximately half the maximum system pressure.
If the pump becomes inoperable during the test, it is disconnected from the supply and the
system filled with water.
20 Stability and mechanical hazards
This clause of Part 1 is applicable.
21 Mechanical strength
This clause of Part 1 is applicable.

– 12 – IEC 60335-2-51:2019 RLV © 2019

22 Construction
This clause of Part 1 is applicable except as follows.

22.101 Circulation pumps shall withstand the water pressure occurring in normal use.

Compliance is checked by subjecting the pump to a water pressure equal to 1,2 times the
maximum system pressure for 1 min.

The pump shall not leak.
23 Internal wiring
This clause of Part 1 is applicable.
24 Components
This clause of Part 1 is applicable except as follows.
24.1.3 Modification:
Switches that are only intended to be operated during installation of the pump are subjected
to 100 cycles of operation.
25 Supply connection and external flexible cords
This clause of Part 1 is applicable except as follows.
25.5 Addition:
Type Z attachment is allowed.
26 Terminals for external conductors
This clause of Part 1 is applicable.
27 Provision for earthing
This clause of Part 1 is applicable.
28 Screws and connections
This clause of Part 1 is applicable.
29 Clearances, creepage distances and solid insulation
This clause of Part 1 is applicable.
30 Resistance to heat and fire
This clause of Part 1 is applicable except as follows.

30.2.2 Not applicable.
31 Resistance to rusting
This clause of Part 1 is applicable.

32 Radiation, toxicity and similar hazards

This clause of Part 1 is applicable.

– 14 – IEC 60335-2-51:2019 RLV © 2019

Annexes
The annexes of Part 1 are applicable except as follows.

Annex A
(informative)
Routine tests
A.2 Electric strength test
Modification:
For appliances with a high leakage current, the value of 30 mA is increased to 70 mA.

Bibliography
The bibliography of Part 1 is applicable except as follows.

Addition:
IEC 60335-2-41, Household and similar electrical appliances – Safety – Part 2-41: Particular
requirements for pumps
___________
IEC 60335-2-51 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical appliances – Safety –
Part 2-51: Particular requirements for stationary circulation pumps for heating
and service water installations

Appareils électrodomestiques et analogues – Sécurité –
Partie 2-51: Exigences particulières pour les pompes de circulation fixes pour
installations de chauffage et de distribution d'eau

– 2 – IEC 60335-2-51:2019 © 2019

CONTENTS
FOREWORD . 3

INTRODUCTION . 5

1 Scope . 6

2 Normative references . 6

3 Terms and definitions . 6

4 General requirement . 7

5 General conditions for the tests . 7
6 Classification . 7
7 Marking and instructions . 8
8 Protection against access to live parts . 8
9 Starting of motor-operated appliances . 8
10 Power input and current . 8
11 Heating . 9
12 Void . 9
13 Leakage current and electric strength at operating temperature . 9
14 Transient overvoltages . 9
15 Moisture resistance . 9
16 Leakage current and electric strength . 9
17 Overload protection of transformers and associated circuits . 10
18 Endurance . 10
19 Abnormal operation . 10
20 Stability and mechanical hazards . 10
21 Mechanical strength . 10
22 Construction . 10
23 Internal wiring . 10
24 Components . 11
25 Supply connection and external flexible cords . 11
26 Terminals for external conductors . 11
27 Provision for earthing . 11

28 Screws and connections . 11
29 Clearances, creepage distances and solid insulation . 11
30 Resistance to heat and fire . 11
31 Resistance to rusting . 11
32 Radiation, toxicity and similar hazards . 11
Annexes . 12
Annex A (informative) Routine tests . 12
Bibliography . 13

Table 101 – Temperature classification of circulation pumps . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES – SAFETY –

Part 2-51: Particular requirements for stationary circulation pumps

for heating and service water installations

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 60335-2-51 has been prepared by IEC technical committee 61:
Safety of household and similar electrical appliances.
This fourth edition cancels and replaces the third edition published in 2002,
Amendment 1:2008 and Amendment 2:2011. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– some instructions are no longer required (7.12);
– converted some notes to normative text (7.12.1, 11.3, 11.8);
– new instructions for installation of thermal insulation (7.12.1);
– the leakage current value is modified (Clause A.2).

– 4 – IEC 60335-2-51:2019 © 2019

The text of this International Standard is based on the following documents:

FDIS Report on voting
61/5785/FDIS 61/5802/RVD
Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

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. It was established on the basis of the fifth edition (2010) 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: Safety requirements for electric stationary
circulation pumps for heating and service water installations.
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 states “addition”, “modification” or “replacement”,
the relevant text in Part 1 is to be adapted accordingly.
NOTE 2 The following numbering system is used:
– subclauses, tables and figures that are numbered starting from 101 are additional to those in Part 1;
– unless notes are in a new subclause or involve notes in Part 1, they are numbered starting from 101, including
those in a replaced clause or subclause;
– additional annexes are lettered AA, BB, etc.
NOTE 3 The following print types are used:
– requirements: in roman type;
– test specifications: in italic type;
– notes: in small roman type.
Words in bold in the text are defined in Clause 3. When a definition concerns an adjective, the adjective and the
associated noun are also in bold.

The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
NOTE 4 The attention of National Committees is drawn to the fact that equipment manufacturers and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests.
It is the recommendation of the committee that the content of this publication be adopted for implementation
nationally not earlier than 12 months or later than 36 months from the date of publication.

INTRODUCTION
It has been assumed in the drafting of this International Standard that the execution of its

provisions is entrusted to appropriately qualified and experienced persons.

This standard recognizes the internationally accepted level of protection against hazards such

as electrical, mechanical, thermal, fire and radiation of appliances when operated as in

normal use taking into account the manufacturer's instructions. It also covers abnormal

situations that can be expected in practice and takes into account the way in which

electromagnetic phenomena can affect the safe operation of appliances.

This standard takes into account the requirements of IEC 60364 as far as possible so that
there is compatibility with the wiring rules when the appliance is connected to the supply
mains. However, national wiring rules may differ.
If an appliance within the scope of this standard also incorporates functions that are covered
by another part 2 of IEC 60335, the relevant part 2 is applied to each function separately, as
far as is reasonable. If applicable, the influence of one function on the other is taken into
account.
When a part 2 standard does not include additional requirements to cover hazards dealt with
in Part 1, Part 1 applies.
NOTE 1 This means that the technical committees responsible for the part 2 standards have determined that it is
not necessary to specify particular requirements for the appliance in question over and above the general
requirements.
This standard is a product family standard dealing with the safety of appliances and takes
precedence over horizontal and generic standards covering the same subject.
NOTE 2 Horizontal and generic standards covering a hazard are not applicable since they have been taken into
consideration when developing the general and particular requirements for the IEC 60335 series of standards. For
example, in the case of temperature requirements for surfaces on many appliances, generic standards, such as
ISO 13732-1 for hot surfaces, are not applicable in addition to Part 1 or part 2 standards.
An appliance that complies with the text of this standard will not necessarily be considered to
comply with the safety principles of the standard if, when examined and tested, it is found to
have other features that impair the level of safety covered by these requirements.
An appliance employing materials or having forms of construction differing from those detailed
in the requirements of this standard may be examined and tested according to the intent of
the requirements and, if found to be substantially equivalent, may be considered to comply
with the standard.
– 6 – IEC 60335-2-51:2019 © 2019

HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES – SAFETY –

Pa
...

IEC 60335-2-51 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical appliances – Safety –
Part 2-51: Particular requirements for stationary circulation pumps for heating
and service water installations

Appareils électrodomestiques et analogues – Sécurité –
Partie 2-51: Exigences particulières pour les pompes de circulation fixes pour
installations de chauffage et de distribution d'eau

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IEC 60335-2-51 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical appliances – Safety –

Part 2-51: Particular requirements for stationary circulation pumps for heating

and service water installations

Appareils électrodomestiques et analogues – Sécurité –

Partie 2-51: Exigences particulières pour les pompes de circulation fixes pour

installations de chauffage et de distribution d'eau

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 23.080; 91.140.10 ISBN 978-2-8322-6811-7

– 2 – IEC 60335-2-51:2019 © 2019
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General requirement . 7
5 General conditions for the tests . 7
6 Classification . 7
7 Marking and instructions . 8
8 Protection against access to live parts . 8
9 Starting of motor-operated appliances . 8
10 Power input and current . 8
11 Heating . 9
12 Void . 9
13 Leakage current and electric strength at operating temperature . 9
14 Transient overvoltages . 9
15 Moisture resistance . 9
16 Leakage current and electric strength . 9
17 Overload protection of transformers and associated circuits . 10
18 Endurance . 10
19 Abnormal operation . 10
20 Stability and mechanical hazards . 10
21 Mechanical strength . 10
22 Construction . 10
23 Internal wiring . 10
24 Components . 11
25 Supply connection and external flexible cords . 11
26 Terminals for external conductors . 11
27 Provision for earthing . 11
28 Screws and connections . 11
29 Clearances, creepage distances and solid insulation . 11
30 Resistance to heat and fire . 11
31 Resistance to rusting . 11
32 Radiation, toxicity and similar hazards . 11
Annexes . 12
Annex A (informative) Routine tests . 12
Bibliography . 13

Table 101 – Temperature classification of circulation pumps . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES – SAFETY –

Part 2-51: Particular requirements for stationary circulation pumps
for heating and service water installations

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60335-2-51 has been prepared by IEC technical committee 61:
Safety of household and similar electrical appliances.
This fourth edition cancels and replaces the third edition published in 2002,
Amendment 1:2008 and Amendment 2:2011. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– some instructions are no longer required (7.12);
– converted some notes to normative text (7.12.1, 11.3, 11.8);
– new instructions for installation of thermal insulation (7.12.1);
– the leakage current value is modified (Clause A.2).

– 4 – IEC 60335-2-51:2019 © 2019
The text of this International Standard is based on the following documents:
FDIS Report on voting
61/5785/FDIS 61/5802/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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. It was established on the basis of the fifth edition (2010) 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: Safety requirements for electric stationary
circulation pumps for heating and service water installations.
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 states “addition”, “modification” or “replacement”,
the relevant text in Part 1 is to be adapted accordingly.
NOTE 2 The following numbering system is used:
– subclauses, tables and figures that are numbered starting from 101 are additional to those in Part 1;
– unless notes are in a new subclause or involve notes in Part 1, they are numbered starting from 101, including
those in a replaced clause or subclause;
– additional annexes are lettered AA, BB, etc.
NOTE 3 The following print types are used:
– requirements: in roman type;
– test specifications: in italic type;
– notes: in small roman type.
Words in bold in the text are defined in Clause 3. When a definition concerns an adjective, the adjective and the
associated noun are also in bold.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
NOTE 4 The attention of National Committees is drawn to the fact that equipment manufacturers and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests.
It is the recommendation of the committee that the content of this publication be adopted for implementation
nationally not earlier than 12 months or later than 36 months from the date of publication.

INTRODUCTION
It has been assumed in the drafting of this International Standard that the execution of its
provisions is entrusted to appropriately qualified and experienced persons.
This standard recognizes the internationally accepted level of protection against hazards such
as electrical, mechanical, thermal, fire and radiation of appliances when operated as in
normal use taking into account the manufacturer's instructions. It also covers abnormal
situations that can be expected in practice and takes into account the way in which
electromagnetic phenomena can affect the safe operation of appliances.
This standard takes into account the requirements of IEC 60364 as far as possible so that
there is compatibility with the wiring rules when the appliance is connected to the supply
mains. However, national wiring rules may differ.
If an appliance within the scope of this standard also incorporates functions that are covered
by another part 2 of IEC 60335, the relevant part 2 is applied to each function separately, as
far as is reasonable. If applicable, the influence of one function on the other is taken into
account.
When a part 2 standard does not include additional requirements to cover hazards dealt with
in Part 1, Part 1 applies.
NOTE 1 This means that the technical committees responsible for the part 2 standards have determined that it is
not necessary to specify particular requirements for the appliance in question over and above the general
requirements.
This standard is a product family standard dealing with the safety of appliances and takes
precedence over horizontal and generic standards covering the same subject.
NOTE 2 Horizontal and generic standards covering a hazard are not applicable since they have been taken into
consideration when developing the general and particular requirements for the IEC 60335 series of standards. For
example, in the case of temperature requirements for surfaces on many appliances, generic standards, such as
ISO 13732-1 for hot surfaces, are not applicable in addition to Part 1 or part 2 standards.
An appliance that complies with the text of this standard will not necessarily be considered to
comply with the safety principles of the standard if, when examined and tested, it is found to
have other features that impair the level of safety covered by these requirements.
An appliance employing materials or having forms of construction differing from those detailed
in the requirements of this standard may be examined and tested according to the intent of
the requirements and, if found to be substantially equivalent, may be considered to comply
with the standard.
– 6 – IEC 60335-2-51:2019 © 2019
HOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES – SAFETY –

Part 2-51: Particular requirements for stationary circulation pumps
for heating and service water installations

1 Scope
This clause of Part 1 is replaced by the following.
This International Standard deals with the safety of electric stationary circulation pumps for
household and similar purposes intended for use in heating systems or in service water
systems, their rated voltage being not more than 250 V for single-phase appliances and
480 V for other appliances.
NOTE 101 The hydraulic and electrical parts of the pump can be in the same enclosure, so that the water flows
through the motor and serves as a coolant, or they can be separated.
Appliances not intended for normal household use, but that nevertheless may be a source of
danger to the public, such as appliances intended to be used by laymen in shops, in light
industry and on farms, are within the scope of this standard.
As far as is practicable, this standard deals with the common hazards presented by
appliances that are encountered by all persons in and around the home. However, in general,
it does not take into account
– persons (including children) whose
• physical, sensory or mental capabilities; or
• lack of experience and knowledge
prevents them from using the appliance safely without supervision or instruction;
– children playing with the appliance.
NOTE 102 Attention is drawn to the fact that
– for appliances intended to be used in vehicles or on board ships or aircraft, additional requirements can be
necessary;
– in many countries additional requirements are specified by the national health authorities, the national
authorities responsible for the protection of labour and similar authorities.
NOTE 103 This standard does not apply to
– pumps for circulating liquids other than water;
– pumps, other than circulation pumps (IEC 60335-2-41);
– circulation pumps intended exclusively for industrial purposes;
– circulation pumps intended to be used in locations where special conditions prevail, such as the presence of a
corrosive or explosive atmosphere (dust, vapour, or gas).
2 Normative references
This clause of Part 1 is applicable.
3 Terms and definitions
This clause of Part 1 is applicable except as follows.

3.1 Definitions relating to physical characteristics
Replacement:
3.1.9
normal operation
operation of the circulation pump with the water pressure and flow rate adjusted within their
specified limits, so that the highest power input is attained
4 General requirement
This clause of Part 1 is applicable.
5 General conditions for the tests
This clause of Part 1 is applicable except as follows.
5.7 Addition:
The water temperature at the inlet is maintained between 0 °C and –5 °C of the value
corresponding to the TF class of the pump.
For circulation pumps intended to be located within the enclosure of a boiler, the tests of
Clauses 10, 11 and 13 are carried out at an ambient temperature of 55 °C or at the
temperature specified in the instructions, whichever is higher.
5.101 Circulation pumps having a three-phase motor that does not incorporate a protective
device are installed with an appropriate device, in accordance with the instructions.
6 Classification
This clause of Part 1 is applicable except as follows.
6.1 Modification:
Circulation pumps shall be class I, class II or class III.
6.2 Addition:
Circulation pumps shall be at least IPX2.
6.101 Circulation pumps shall be of one of the classes shown in Table 101.
Table 101 – Temperature classification of circulation pumps
Class Maximum temperature of
the circulating water
°C
TF  60 60
TF  95 95
TF 110 110
– 8 – IEC 60335-2-51:2019 © 2019
Compliance is checked by inspection.
7 Marking and instructions
This clause of Part 1 is applicable except as follows.
7.1 Addition:
Circulation pumps shall be marked with
– the TF class;
– the direction of the water flow;
– the direction of rotation (for pumps having three-phase motors);
– the rated current (for pumps having three-phase motors if a protective device has to be
installed in the fixed wiring).
7.12 Modification:
The instruction concerning persons (including children) with reduced physical, sensory or
mental capabilities, or lack of experience and knowledge is not applicable.
The instruction regarding supervision of children is not applicable.
7.12.1 Addition:
The installation instructions shall state the substance of the following:
– the maximum flow rate or total head;
– the maximum ambient temperature at which the pump is to be used;
– the maximum system pressure, which shall not be less than:
• 0,6 MPa for pumps for heating systems;
• 1,0 MPa for pumps for service water systems;
– the intended orientation of the pump;
– a protective device is to be installed in the fixed wiring and its characteristics are to be
specified (for pumps having a three-phase motor not incorporating a protective device).
– for the thermal insulation of circulation pumps in heating systems, only the supplied kit or
a kit made available by the manufacturer shall be used. It shall be ensured that the drain
openings of the motor are not sealed after installation of the thermal insulation.
8 Protection against access to live parts
This clause of Part 1 is applicable.
9 Starting of motor-operated appliances
This clause of Part 1 is not applicable.
10 Power input and current
This clause of Part 1 is applicable.

11 Heating
This clause of Part 1 is applicable except as follows.
11.2 Addition:
Circulation pumps that are only fixed by the water pipes are positioned against one wall of the
test corner and away from the other.
11.3 Addition:
The temperatures t and t are the ambient temperatures of the environment in which the
1 2
pump is installed, for instance inside the enclosure of a boiler.
11.7 Replacement:
Circulation pumps are operated until steady conditions are established.
11.8 Addition:
The temperature rise limits of pumps located within the enclosure of a boiler are reduced by
the difference between the ambient temperature at which the test is carried out and 25 °C.
The temperature rise of the external enclosure is not measured.
For circulation pumps in which water flows through the motor, the temperature rise limits for
windings are increased by 5 K. The temperature rise limits are increased further by
– 5 K, if the winding insulation is class 130 (B);
– 10 K, if the winding insulation is class 155 (F) or 180 (H).
For circulation pumps in which water flows through the motor, the increase of 5 K allowed by
a
footnote to Table 3 does not apply.
12 Void
13 Leakage current and electric strength at operating temperature
This clause of Part 1 is applicable.
14 Transient overvoltages
This clause of Part 1 is applicable.
15 Moisture resistance
This clause of Part 1 is applicable.
16 Leakage current and electric strength
This clause of Part 1 is applicable.

– 10 – IEC 60335-2-51:2019 © 2019
17 Overload protection of transformers and associated circuits
This clause of Part 1 is applicable.
18 Endurance
This clause of Part 1 is not applicable.
19 Abnormal operation
This clause of Part 1 is applicable except as follows.
19.1 Addition:
Circulation pumps are also subjected to the test of 19.101.
19.7 Addition:
The test is carried out with the water flow stopped or reduced to 5 l/min, whichever is more
unfavourable.
19.101 Circulation pumps are supplied at rated voltage and operated at approximately half
the maximum system pressure for 5 min, after which the water is drained off and the operation
continued for 7 h. The system is replenished with water and the pump operated again for
5 min at approximately half the maximum system pressure.
If the pump becomes inoperable during the test, it is disconnected from the supply and the
system filled with water.
20 Stability and mechanical hazards
This clause of Part 1 is applicable.
21 Mechanical strength
This clause of Part 1 is applicable.
22 Construction
This clause of Part 1 is applicable except as follows.
22.101 Circulation pumps shall withstand the water pressure occurring in normal use.
Compliance is checked by subjecting the pump to a water pressure equal to 1,2 times the
maximum system pressure for 1 min.
The pump shall not leak.
23 Internal wiring
This clause of Part 1 is applicable.
...