IEC 60309-4:2021

IEC 60309-4 ®
Edition 2.0 2021-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Plugs, fixed or portable socket-outlets and appliance inlets for industrial
purposes –
Part 4: Switched socket-outlets with or without interlock

Fiches, socles fixes de prise de courant, prises mobiles et socles de connecteur
pour usages industriels –
Partie 4: Socles de prise de courant avec interrupteur, avec ou sans dispositif
de verrouillage
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IEC 60309-4 ®
Edition 2.0 2021-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Plugs, fixed or portable socket-outlets and appliance inlets for industrial

purposes –
Part 4: Switched socket-outlets with or without interlock

Fiches, socles fixes de prise de courant, prises mobiles et socles de connecteur

pour usages industriels –
Partie 4: Socles de prise de courant avec interrupteur, avec ou sans dispositif

de verrouillage
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.30 ISBN 978-2-8322-9847-3

– 2 – IEC 60309-4:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 General . 7
5 Standard ratings . 8
6 Classification of accessories . 8
7 Marking . 9
8 Dimensions. 10
9 Protection against electric shock . 11
10 Provision for earthing . 12
11 Terminals and terminations . 12
12 Interlocks, switches and their components . 12
13 Resistance to ageing of rubber and thermoplastic material . 17
14 Construction . 17
15 Construction of fixed socket-outlets . 17
16 Construction of plugs and portable socket-outlets . 17
17 Construction of appliance inlets . 17
18 Degrees of protection . 17
19 Insulation resistance and dielectric strength . 18
20 Breaking capacity . 18
21 Normal operation . 18
22 Temperature rise . 18
23 Flexible cables and their connection . 20
24 Mechanical strength . 20
25 Screws, current-carrying parts and connections . 21
26 Creepage distances, clearances and distances through sealing compound . 21
27 Resistance to heat, to fire and to tracking . 21
28 Corrosion and resistance to rusting . 22
29 Conditional short-circuit current withstand test . 22
30 Electromagnetic compatibility . 22

Figure 401 – Example of apparatus for checking the withdrawal force . 15
Figure 402 – Actuator applied force F . 21

Table 401 – Withdrawal force with respect to ratings . 14
Table 11 – Temperature rise test . 19
Table 402 – Actuator test force F . 20

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PLUGS, FIXED OR PORTABLE SOCKET-OUTLETS AND
APPLIANCE INLETS FOR INDUSTRIAL PURPOSES –

Part 4: Switched socket-outlets
with or without interlock
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-
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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 60309-4 has been prepared by subcommittee 23H: Plugs,
socket-outlets and couplers for industrial and similar applications, and for electric vehicles, of
IEC technical committee 23: Electrical accessories.
This second edition cancels and replaces the first edition published in 2006 and
Amendment 1:2012. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– updated in order to take into account the technical revisions to IEC 60309-1 and to
IEC 60309-2.
– 4 – IEC 60309-4:2021 © IEC 2021
The text of this International Standard is based on the following documents:
FDIS Report on voting
23H/482/FDIS 23H/488/RVD
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/standardsdev/publications.
This document is to be read in conjunction with IEC 60309-1:2021 and with
IEC 60309-2:2021.
In this document, the following print types are used:
– requirements proper: in roman type;
– test specifications: in italic type;
– notes: in smaller roman type.
IEC 60309-1:2021 deals with general requirements and comprises all clauses of a general
character.
Subsequent parts deal with the requirements of particular types of accessories. The clauses
of these particular requirements supplement or modify the corresponding clauses of
IEC 60309-1:2021 or of IEC 60309-2:2021.
Clauses, subclauses, figures, tables and notes which are additional to those of
IEC 60309-1:2021 or of IEC 60309-2:2021 are numbered starting from 401.
A list of all parts in the IEC 60309 series, published under the general title Plugs, fixed or
portable socket-outlets and appliance inlets for industrial purposes, can be found on the IEC
website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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.
PLUGS, FIXED OR PORTABLE SOCKET-OUTLETS AND
APPLIANCE INLETS FOR INDUSTRIAL PURPOSES –

Part 4: Switched socket-outlets
with or without interlock
1 Scope
Clause 1 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies as follows:
Replace the first two paragraphs by the following:
This part of IEC 60309 applies to self-contained products primarily intended for industrial use,
either indoors or outdoors that combine the following items within a single enclosure:
– a fixed or portable socket-outlet according to IEC 60309-1 or IEC 60309-2 with a rated
operating voltage not exceeding 1 000 V DC or 1 000 V AC with a frequency not
exceeding 500 Hz and a rated current not exceeding 800 A;
– a switching device.
These products can incorporate an interlock and/or protective devices.
These accessories are intended to be installed by instructed persons or skilled persons only.
2 Normative references
Clause 2 of IEC 60309-1:2021 applies except as follows:
Additional normative references:
IEC 60073, Basic and safety principles for man-machine interface, marking and identification
– Coding principles for indicators and actuators
IEC 60309-1:2021, Plugs, fixed or portable socket-outlets and appliance inlets for industrial
purposes – Part 1: General requirements
IEC 60309-2:2021, Plugs, fixed or portable socket-outlets and appliance inlets for industrial
purposes – Part 2: Dimensional compatibility requirements for pin and contact-tube
accessories
IEC 60617, Graphical symbols for diagrams (available at http://std.iec.ch/iec60617)
IEC 60947-1:2020, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-3, Low-voltage switchgear and controlgear – Part 3: Switches, disconnectors,
switch-disconnectors and fuse-combination units
IEC 60947-4-1, Low-voltage switchgear and controlgear – Part 4-1: Contactors and motor-
starters – Electromechanical contactors and motor-starters
IEC 60947-5-1, Low-voltage switchgear and controlgear – Part 5-1: Control circuit devices
and switching elements – Electromechanical control circuit devices

– 6 – IEC 60309-4:2021 © IEC 2021
IEC 61058-1, Switches for appliances – Part 1: General requirements
3 Terms and definitions
Clause 3 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
Terms and definitions 3.6 to 3.9 do not apply.
Add the following terms and definitions:
3.401
switched socket-outlet
product (interlocked or non-interlocked) containing in a single enclosure a switching device
and a socket-outlet, intended to be used in combination
3.402
interlocked socket-outlet
socket-outlet associated with an interlock
3.403
switching device
device designated to make or break the current in one or more electric circuits
[SOURCE IEC 60050-441:1984, 441-14-01]
3.403.1
mechanical switching device
switching device designed to close and open one or more electric circuits by means of
separable contacts
[SOURCE: IEC 60050-441:1984, 441-14-02, modified – The note has been omitted.]
3.403.1.1
(mechanical) switch
mechanical switching device capable of making, carrying and breaking currents under normal
circuit conditions which may include specified operating overload conditions and also carrying
for a specified time currents under specified abnormal circuit conditions such as those of
short-circuit
Note 1 to entry: A switch may be capable of making, but not breaking short-circuit currents.
[SOURCE: IEC 60050-411:1984, 441-14-10]
3.403.1.2
switch-disconnector
switch which, in the open position, complies with the requirements specified for the isolating
function
[SOURCE: IEC 60050-411:1984, 441-14-12, modified – Reference made to the isolating
function instead of to the requirements specified for a disconnector.]

3.403.1.3
contactor
mechanical switching device having only one position of rest, operated otherwise than by
hand, capable of making, carrying and breaking currents under normal circuit conditions
including operating overload conditions
[SOURCE: IEC 60050-411:1984, 441-14-33, modified – "mechanical" has been omitted from
the term and the note has been deleted.]
3.403.2
associated switching device
separate switching device which can be replaced independently
3.403.3
integral switching device
switching device constructed as a part of a socket-outlet covered by this document, where
neither the switching device nor the socket-outlet can be replaced independently
3.404
isolation
disconnection of an installation or its discrete section from any source of the electric energy
for purposes of electrical safety
[SOURCE: IEC 60947-1:2020, 3.3.19]
3.405
utilization category (for a switching device)
combination of specified requirements related to the condition in which the switching device
fulfils its purpose, selected to represent a characteristic group of practical applications
Note 1 to entry: The specified requirements may concern e.g. the values of making capacities (if applicable),
breaking capacities and other characteristics, the associated circuits and the relevant conditions of use and
behaviour.
[SOURCE: IEC 60050-411:1984, 441-17-19, modified – Deletion of "or a fuse" from the
domain, and "or the fuse" from the definition.]
3.406
control circuit device
electrical device intended for the controlling, signalling, interlocking, etc. of switchgear and
controlgear
Note 1 to entry: See IEC 60947-1:2020, 3.4.16.
3.407
latching device
part of the interlock mechanism provided to hold a plug or appliance inlet in the socket-outlet
4 General
Clause 4 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
Additional subclause:
4.401 Components incorporated or integrated in products (e.g. flexible cable, current
cut-outs, thermal cut-outs, safety transformers, switches, fuses, residual current devices,
lamp holders and connecting devices) shall comply with the relevant standards as far as they
reasonably apply.
– 8 – IEC 60309-4:2021 © IEC 2021
5 Standard ratings
Clause 5 of IEC 60309-1:2021 applies for products incorporating socket-outlets according to
IEC 60309-1.
Clause 5 of IEC 60309-2:2021 applies with the following addition for products incorporating
socket-outlets according to IEC 60309-2:2021.
Add the following at the end of 5.201:
For switched socket-outlets with or without interlock according to 6.401, the whole unit can
have a different degree of protection but not lower than IP44 (see also 8.1).
6 Classification of accessories
Clause 6 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
6.1 Replacement:
According to purpose:
– fixed socket-outlets,
– portable socket-outlets.
6.5 Not applicable.
Additional subclauses:
6.401 According to switching devices and interlock facilities:
– products with a switching device and without an interlock;
– products with a switching device and with an interlock.
6.402 According to the operation of the interlock/switching device:
– manually;
– automatically (electrically and/or electronically);
– combination of the above.
NOTE Inserting the plug is not considered a manual operation of the interlock/switching device.
6.403 According to the mechanical switching device:
– switch;
– switch-disconnector;
– contactor;
– other devices with suitable switch rating.
6.404 According to suitability for isolation of the switching device:
– suitable for isolation;
– not suitable for isolation.
6.405 According to whether the interlock system has a latching device:
– with latching device (mechanical interlock);

– without latching device (electrical interlock).
6.406 According to the presence of a protective device:
– with protective device;
– without protective device.
7 Marking
Clause 7 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
7.1 Add the following items to the list:
i) indication of the open and closed position of the switching device for products with
isolating function according to 6.404;
j) indication of the type of switching device.
7.2 Add the following to the existing list of symbols:

Open position and/or OFF
IEC 60417-5008
(2002-10)
Closed position and/or ON
IEC 60417-5007
(2002-10)
a)b)
Switch or
a)b)
Switch-disconnector
a)b)
Contactor
a)
Other devices According to their relevant standard
a)
Graphical symbol may appear in a vertical or horizontal orientation.
b)
In the absence of symbols for marking on equipment, symbols for diagrams according to
IEC 60617 are used.
7.4 Not applicable.
– 10 – IEC 60309-4:2021 © IEC 2021
7.5 Replacement:
The neutral terminal, if any, shall be marked N.
The earth terminal, if any, shall be marked (preferred) IEC 60417-5019 (2006-08) or
IEC 60417-5017 (2006-08).
The relationship between the terminals for the supply cable and load terminals / load contacts
shall be made clear, if necessary, by means of a diagram or instruction.
Additional marking to indicate neutral terminal and/or earthing terminal may be used as
follows:
– letter W and/or white colour for neutral;
– letter G and/or green colour for earthing.
No marking is required for terminals for pilot conductors. In the event that they are marked, it
is recommended to use the marking P or PILOT.
Compliance is checked by inspection.
7.6 Replacement of the first sentence by the following text:
7.6 Marking on the outside of the enclosure shall be indelible and easily legible.
Additional subclauses:
7.401 The position (open or closed) of the switching device shall be unambiguous and
clearly indicated.
The actuator of a mechanical switching device may be used to indicate the position of the
contacts.
For mechanical switching devices operated by means of two push-buttons, only the push-
button designated for the opening operation shall be red or marked with the symbol "O".
The colours of other push-buttons, illuminated push-buttons and indicator lights shall be in
accordance with IEC 60073.
7.402 The marking of the type of switching device shall be in a place which is visible after
installation of the products, on the outside of the enclosure or on the lid, if any, if the latter
cannot be removed without the aid of a tool.
8 Dimensions
Clause 8 of IEC 60309-1:2021 applies for products incorporating socket-outlets according to
IEC 60309-1.
Clause 8 of IEC 60309-2:2021 applies with the following addition for products incorporating
socket-outlets according to IEC 60309-2:

8.1 Add the following after the first paragraph:
Switched socket-outlets according to 6.401 with degree of protection higher than IP44 and
different from IP67, shall use socket-outlets that comply with construction as stated in
standard sheet 2-I (continuation 2) or 2-III (continuation 2) or 2-VIII (continuation 2).
9 Protection against electric shock
Replacement of Clause 9 of IEC 60309-1:2021 or of IEC 60309-2:2021 by the following:
9.1
9.1.1 The enclosure shall be designed so that live parts are not accessible when in normal
use and when parts which can be removed without the aid of a tool have been removed.
Compliance is checked by inspection and, if necessary, by the tests of 9.1.2 to 9.1.4.
9.1.2 The standard test finger according to IEC 61032, Probe B is applied with a force of
10 N ± 1 N in every possible position. An electrical indicator with a voltage not less than 40 V
and not more than 50 V is used to show contact with the relevant part.
9.1.3 For elastomeric or thermoplastic enclosures, the following test is made at an ambient
temperature of 35 °C ± 2 °C, the products being at this temperature.
During this test, the parts of elastomeric or thermoplastic material of the products are
subjected for 1 min to a force of 75 N, applied through the tip of a straight unjointed test finger
of the same dimensions as the standard test finger. This finger, with an electrical indicator as
described above, is applied to all places where yielding of the insulating material could impair
the safety of the product.
During this test, the product shall not deform to such an extent that live parts become
accessible.
+0,1
9.1.4 The test probe D of IEC 61032 is applied with a force of 1 N.
This test does not apply to the components fitted to the product.
The test wire is provided with an electrical indicator, with a voltage not less than 40 V and not
more than 50 V, to show contact with the relevant part.
The protection is satisfactory if the wire cannot enter the enclosure, or if it enters, it does not
touch live parts inside the enclosure.
9.2 Parts providing protection against electric shock shall have adequate mechanical
strength and shall be reliably secured by means of screws or in a similar reliable manner so
that they will not loosen in normal use.
Compliance is checked by inspection and by the tests of Clause 24 and Clause 25.
9.3 Knobs, operating levers, push-buttons, rockers and the like, for operating switches in
switched socket-outlets shall be of insulating material, unless their accessible metal parts are
separated from the metal parts of the mechanism by double insulation or reinforced insulation,
or they are reliably connected to earth.
Compliance is checked by inspection and by the tests of Clause 19 and Clause 22.

– 12 – IEC 60309-4:2021 © IEC 2021
10 Provision for earthing
Clause 10 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
10.1 Replace the first paragraph by the following:
Products with earthing contact shall be provided with an earthing terminal. Metal-clad fixed
products with an internal earthing terminal can, in addition, be provided with an external
earthing terminal, which, except for flush type products, shall be visible from the outside.
The earthing terminal of the socket-outlet may be used provided it is easily accessible.
11 Terminals and terminations
Clause 11 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies.
12 Interlocks
Replace Clause 12 of IEC 60309-1:2021 or of IEC 60309-2:2021 by the following:
12 Interlocks, switches and their components
12.1 Switched socket-outlets with interlocks shall be so constructed that a plug or appliance
inlet cannot be completely withdrawn from the socket-outlet while the contacts of that socket-
outlet are live, and the contacts of the socket-outlet cannot be made live until a plug or
appliance inlet is in proper engagement. The contacts shall not open or close on load.
A pilot contact in a switched socket-outlet (interlocked or non-interlocked) may be live when
not engaged with a male pilot contact if the female contact is part of a SELV circuit or if it is
not accessible with the standard test finger according to IEC 61032, Probe B.
NOTE SELV is defined in IEC 60364-4-41 .
Socket-outlets shall be so designed that, after engagement with a complementary accessory,
the interlock operates correctly.
The operation of an interlock shall not be impaired by normal wear of the portion of the plug
or appliance inlet used for interlocking.
Compliance is checked by carrying out the tests of 12.2 or 12.3 as applicable after the test of
Clause 21.
12.2 Switched socket-outlets with interlock but without latching function (electrical interlock)
shall be so constructed that:
– the time interval between the opening of the contacts of the control switching device and
the opening of the contacts of the main poles shall ensure that the mechanical switching
device interrupts the current before the contacts of the plug or appliance inlet are
disconnected from the contacts of the socket-outlet;
– during the closing operation, the contacts of the control switching device or the pilot
contact shall close after or simultaneously with the power contacts.
______________
IEC 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety – Protection against
electric shock
Compliance is checked by the following test:
For products provided with an actuator, an attempt shall be made, without the complementary
accessory inserted, to close the mechanical switching device by applying a force according to
24.401. The contacts of the mechanical switching device shall not close.
This is checked by a continuity test made between the supply terminals and the contact
assembly of the socket-outlet.
The time interval is checked by measuring the time interval between the instant of opening of
the contact(s) of the control switching device or pilot contacts and the instant of opening of
the contact of the mechanical switching device, under no-load conditions.
For 60/63 A and 100/125 A products complying with IEC 60309-2 where the control switching
device depends on the pilot pin and pilot contact-tube, the time interval shall not be greater
than 35 ms.
NOTE The time interval of 35 ms is the ratio between the distances given in the standard sheets in the worst
conditions and the separation speed given in Clause 20 and Clause 21.
12.3 Switched socket-outlets with interlock with latching devices locking the plug or
appliance inlet into the socket-outlet (mechanical interlock) shall be so constructed that the
interlock is linked with the operation of a switching device so that the plug or appliance inlet
can neither be inserted nor withdrawn from the socket-outlet while the contacts of the socket-
outlet are live and the contacts of the socket-outlet cannot be made live until a plug is almost
completely in engagement.
Compliance is checked by inspection, by a manual test and by the following test.
Products with interlock and latching devices, which hold the plug into the socket-outlet, are
subjected to the following test:
Without the complementary accessory inserted, an attempt shall be made to close the
mechanical switching device by applying a force according to 24.401. The contacts of the
mechanical switching device shall not close.
This is checked by a continuity test made between the supply terminals and the contact
assembly of the socket-outlet.
The switched socket-outlet with interlock is fixed to the support of an apparatus as shown in
Figure 401 so that the axis of separation is vertical, and the movement of the plug is
downwards. With the latching device(s) holding the test plug into the socket-outlet in the
engaged position, an axial pull is applied to an appropriate test plug inserted in the switched
socket-outlet with interlock. The test plug, according to the relevant standard sheets, shall
have finely ground contacts of hardened steel, having a surface roughness not exceeding
0,8 µm over their active length and spaced at the nominal distances, with a tolerance of
±0,05 mm.
The dimension of the test plug contacts or the distance between contact surfaces for other
types of plug contacts shall be in accordance with the minimum dimension(s) given in the
+0,01
relevant standard sheets, with a tolerance of mm.
The test plug contacts are wiped free from grease before test.

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The test plug is inserted into and withdrawn from the socket-outlet ten times. It is then
inserted again, a mass being attached to it by means of a suitable clamp. The total mass of
the test plug, the clamp, the carrier, the principal and the supplementary weight shall exert a
pull force according to Table 401. The supplementary weight shall be such that it exerts a
force equal to one-tenth of the withdrawal force. The retaining means, if any, shall be opened.
The principal weight is hung without jolting on the test plug, and the supplementary weight is
allowed to fall from a height of 5 cm onto the principal weight.
Table 401 – Withdrawal force with respect to ratings
Rated current Withdrawal force
A N
Series I Series II Other ratings
16 20 165
32 30 165
63 60 300
125 100 440
250 200 160 660
315 800
400 500 1 000
600 1 200
Dimensions in millimetres
Key
A – Support
B – Sample
C – Test plug
D – Supplementary sliding weight
E – Principal weight
Figure 401 – Example of apparatus for checking the withdrawal force
During the test the test plug shall not come out of the socket-outlet and the latching devices
holding the test plug in the socket-outlet shall remain in locked position.
During the test the electrical continuity shall be maintained.
After the test, the switched socket-outlet with interlock shall show no damage or deformation
which may impair the function of the product.
Compliance is checked by inspection and test.
12.4 Switching devices shall have at least the same number of poles as the socket-outlet.
NOTE Switching of the neutral depends on national regulations.
For this purpose, the earthing contact is not considered as a pole and shall not be switched.
Compliance is checked by inspection.
12.5 Associated switches and switch-disconnectors for switched socket-outlets shall comply
with IEC 60947-3 and:
– for AC application, they shall have a rated current at a utilization category of at least
AC-22A, not less than the rated current of the associated socket-outlet;

– 16 – IEC 60309-4:2021 © IEC 2021
– for DC application, they shall have a rated current at a utilization category of at least
DC-21A, not less than the rated current of the associated socket-outlet.
Compliance is checked by inspection, by measurement and by tests.
12.6 Associated contactors for switched socket-outlets shall comply with IEC 60947-4-1 and,
– for AC application, they shall have a rated current, at a utilization category of at least
AC-2, not less than the rated current of the associated socket-outlet;
– for DC application, they shall have a rated current, at a utilization category of at least
DC-3, not less than the rated current of the associated socket-outlet.
Compliance is checked by inspection, by measurement and by tests.
12.7 Other associated devices are under consideration.
12.8 Integral switching devices shall comply with IEC 60947-3 as far as it is applicable and,
– for AC application, they shall have a rated current, at a utilization category of at least
AC-22A, not less that the rated current of the associated socket-outlet;
– for DC application, they shall have a rated current, at a utilization category of at least
DC-21A, not less than the rated current of the associated socket-outlet.
12.9 Control circuit devices and switching elements, if any, used in the control circuit of an
electrically interlocked socket-outlet shall comply with IEC 60947-5-1 or with IEC 61058-1 and
they shall have ratings suitable for the load to be controlled.
Control switching devices according to IEC 61058-1 shall be classified with at least
6 000 cycles.
Compliance is checked by inspection, by measurement and by tests.
12.10 Switching devices according to 12.5, 12.6, 12.7 and 12.8 shall comply with Clause 29,
unless already tested to the relevant standard for short-circuit current withstand of at least
10 kA.
Compliance is checked by inspection, by measurement and by tests.
12.11 Switching devices suitable for isolation shall provide in the open position an isolation
distance in accordance with the requirements of IEC 60947-1, necessary to satisfy the
isolating function (see 3.404).
For switching devices suitable for isolation, indication of the position of the main contacts
shall be provided by one of the following means:
– the position of the actuator, or
– a separate mechanical indicator.
This indication shall be visible when the product is in its normal working position.
When the operating means of the mechanical switching device is used to indicate the open or
closed positions, the mechanical strength of the actuating mechanism and the reliability of the
indication of the open position shall be adequate.
Compliance is checked by inspection and by the test of 24.401.
12.12 Means may be provided by the manufacturer to enable the mechanical switching device
to be locked in the open position, for example, using padlock(s).

Locking in the closed position is permitted for particular applications.
If locking means are provided, the locking means shall be designed in such a way that they
cannot be removed with the appropriate padlock(s) installed without the aid of a tool.
When the mechanical switching device is locked by even a single padlock, it shall not be
possible by operating the actuator, to reduce the clearance between open contacts to the
extent that it no longer complies with the requirements for clearances of IEC 60947-1.
Alternatively, the design may provide lockable means to prevent access to the operating
means of the mechanical switching device.
Compliance is checked by inspection and by the test of 24.402.
12.13 Pilot contacts and auxiliary circuits used for interlocks shall make after the neutral and
phase(s) are made.
Pilot contacts and auxiliary circuits used for interlocks shall break before the phase(s) and
neutral are broken.
Compliance is checked by inspection and by the test of 12.2.
13 Resistance to ageing of rubber and thermoplastic material
Clause 13 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies.
14 Construction
Clause 14 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
Additional subclause:
14.401 Products with a rated current above 250 A shall be provided with an interlock.
15 Construction of fixed socket-outlets
Clause 15 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies.
16 Construction of plugs and portable socket-outlets
Clause 16 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies.
17 Construction of appliance inlets
Clause 17 of IEC 60309-1:2021 or of IEC 60309-2:2021 does not apply.
18 Degrees of protection
Clause 18 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies.

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19 Insulation resistance and dielectric strength
Clause 19 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
19.1 Add the following after the third paragraph:
For switched socket-outlets, the test is carried out with the switch in the ON position.
20 Breaking capacity
Clause 20 of IEC 60309-1:2021 or of IEC 60309-2:2021 applies except as follows:
Add the following after the fourth paragraph:
A non-interlocked switched socket-outlet with an associated switching device shall be tested
with the switching device in the ON position.
A non-interlocked switched socket-outlet with an integral switching device shall be tested
twice, the first test with the switching device in the ON position (socket-outlet test), the
second test with the plug rem
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