3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following

3.1 General terms
3.1.1
overcurrent
current exceeding the rated current
[SOURCE: IEC 60050-441:1984, 441-11-06]
3.1.2
short-circuit
accidental or intentional conductive path between two or more conductive parts forcing the
electric potential differences between these conductive parts to be equal to or close to zero
[SOURCE: IEC 60050-151:2001, 151-12-04]
3.1.3
short-circuit current
overcurrent resulting from a short circuit due to a fault or an incorrect connection in an electric
circuit
[SOURCE: IEC 60050-441:1984, 441-11-07]
– 14 – IEC 61095:2023 © IEC 2023
3.1.4
overload
operating conditions in an electrically undamaged circuit, which cause an overcurrent
[SOURCE: IEC 60050-441:1984, 441-11-08]
3.1.5
overload current
overcurrent occurring in an electrically undamaged circuit
3.1.6
ambient air temperature
temperature, determined under prescribed conditions, of the air surrounding the complete
switching device or fuse
Note 1 to entry: For switching devices or fuses installed inside an enclosure, it is the temperature of the air outside
the enclosure.
[SOURCE: IEC 60050-441:1984, 441-11-13]
3.1.7
conductive part
part which is capable of conducting current although it may not necessarily be used for carrying
service current
[SOURCE: IEC 60050-441:1984, 441-11-09]
3.1.8
exposed conductive part
conductive part which can readily be touched and which is not normally alive, but which may
become alive under fault conditions
Note 1 to entry: Typical exposed conductive parts are walls of enclosures, operating handles, etc.
[SOURCE: IEC 60050-441:1984, 441-11-10]
3.1.9
electric shock
physiological effect resulting from an electric current through a human or livestock
[SOURCE: IEC 60050-826:2022, 826-12-01]
3.1.10
live part
conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor or PEM conductor or PEL conductor
Note 1 to entry: This concept does not necessarily imply a risk of electric shock.
[SOURCE: IEC 60050-826:2022, 826-12-08, modified ─ Rewording of the definition and
addition of a Note 1 to entry.]
IEC 61095:2023 © IEC 2023 – 15 –
3.1.11
protective conductor (identification: PE)
conductor provided for purposes of safety
EXAMPLE Protection against electric shock.
Note 1 to entry: In an electrical installation, the conductor identified PE is normally also considered as protective
earthing conductor.
[SOURCE: IEC 60050-826:2022, 826-13-22, modified ─ Rewording of the definition, addition of
a new example and a new Note 1 to entry.]
3.1.12
neutral conductor
conductor electrically connected to the neutral point and capable of contributing to the
distribution of electric energy
[SOURCE: IEC 60050-826:2021, 826-14-07]
3.1.13
PEN conductor
conductor combining the functions of both a protective earthing conductor and a neutral
conductor
[SOURCE: IEC 60050-826:2022, 826-13-25]
3.1.14
PEM conductor
conductor combining the functions of both a protective earthing conductor and a mid-point
conductor
[SOURCE: IEC 60050-826:2022, 826-13-26]
3.1.15
PEL conductor
conductor combining the functions of both a protective earthing conductor and a line conductor
[SOURCE: IEC 60050-826:2022, 826-13-27]
3.1.16
enclosure
part providing a specified degree of protection of equipment against certain external influences
and a specified degree of protection against approach to or contact with live parts and moving
parts
Note 1 to entry: This definition is similar to IEC 60050-441:1984, 441-13-01, which applies to assemblies.
[SOURCE: IEC 60050-441:1984, 441-13-01, modified ─ Rewording of the definition and new
Note 1 to entry.]
3.1.17
integral enclosure
enclosure which forms an integral part of the equipment
– 16 – IEC 61095:2023 © IEC 2023
3.1.18
utilization category
<switching device or fuse> combination of specified requirements related to the condition in
which the switching device or the fuse fulfils its purpose, selected to represent a characteristic
group of practical applications
Note 1 to entry: The specified requirements can 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 60050-441:1984, 441-17-19]
3.2 Switching devices
3.2.1
switching device
device designed to make or break the current in one or more electric circuits
Note 1 to entry: A switching device can perform one or both of these operations.
[SOURCE: IEC 60050-441:1984, 441-14-01, modified ─ Addition of a Note 1 to entry.]
3.2.2
mechanical switching device
switching device designed to close and open one or more electric circuits by means of separable
contacts
Note 1 to entry: Any mechanical switching device can be designated according to the medium in which its contacts
open and close, e.g. air, SF6, oil.
[SOURCE: IEC 60050-441:1984, 441-14-02]
3.2.3
semiconductor switching device
switching device designed to make and/or break the current in an electric circuit by means of
the controlled conductivity of a semiconductor
Note 1 to entry: This definition differs from IEC 60050-441:1984, 441-14-03 since a semiconductor switching device
is also designed for breaking the current.
[SOURCE: IEC 60050-441:1984, 441-14-03, modified ─ Addition of “and/or break” and new
Note 1 to entry.]
3.2.4
fuse
device that, by the fusing of one or more of its specially designed and proportioned components,
opens the circuit in which it is inserted by breaking the current when this exceeds a given value
for a sufficient time
Note 1 to entry: The fuse comprises all the parts that form the complete device
[SOURCE: IEC 60050-441:1984, 441-18-01]
3.2.5
circuit-breaker
mechanical switching device, capable of making, carrying and breaking currents under normal
circuit conditions and also making, carrying for a specified time and breaking currents under
specified abnormal circuit conditions such as those of short circuit
[SOURCE: IEC 60050-441:1984, 441-14-20, modified ─ “Duration” replaced with “time”.]
IEC 61095:2023 © IEC 2023 – 17 –
3.2.6
mechanical contactor
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
Note 1 to entry: The term “operated otherwise than by hand” means that the device is intended to be controlled and
kept in working position from one or more external supplies.
Note 2 to entry: A household contactor can have a handle as additional means for operation. In some countries,
contactors can be controlled by a signal from the energy supplier during off-peak hours. An end user is allowed to
open or close manually the contactor if necessary.
Note 3 to entry: A contactor is usually intended to operate frequently.
[SOURCE: IEC 60050-441:1984, 441-14-33, modified ─ Addition of Notes to entry.]
3.2.7
electromagnetic contactor
contactor, in which the force for closing the normally open main contacts or opening the
normally closed main contacts is provided by an electromagnet
Note 1 to entry: The electromagnet can be electronically controlled.
3.2.8
electronically controlled electromagnet
electromagnet in which the coil is controlled by a circuit with active electronic elements
3.2.9
latched contactor
contactor, the moving elements of which are prevented by means of a latching arrangement
from returning to the position of rest when the operating means are de-energized
Note 1 to entry: The latching, and the release of the latching, can be mechanical, electromagnetic, pneumatic, etc.
Note 2 to entry: Because of the latching, the latched contactor actually acquires a second position of rest and,
according to 3.2.6 is not, strictly speaking, a contactor. However, since the latched contactor in both its utilization
and its design is more closely related to contactors in general than to any other classification of switching device, it
is considered proper to require that it complies with the specifications for contactors wherever they are appropriate.
[SOURCE: IEC 60050-441:1984, 441-14-34]
3.2.10
semiconductor contactor
solid state contactor
device which performs the function of a contactor by utilizing a semiconductor switching device
Note 1 to entry: A semiconductor contactor can also contain mechanical switching devices.
3.2.11
pilot switch
non-manual control switch actuated in response to specified conditions of an actuating quantity
Note 1 to entry: The actuating quantity can be pressure, temperature, velocity, liquid level, elapsed time, etc.
[SOURCE: IEC 60050-441:1984, 441-14-48]
– 18 – IEC 61095:2023 © IEC 2023
3.2.12
push-button
control switch having an actuator intended to be operated by force exerted by a part of the
human body, usually the finger or palm of the hand, and having stored energy (spring) return
[SOURCE: IEC 60050-441:1984, 441-14-53]
3.2.13
short-circuit protective device
SCPD
device intended to protect a circuit or parts of a circuit against short-circuit currents by
interrupting them
3.2.14
surge arrester
device designed to protect the electrical apparatus from high transient overvoltages and to limit
the duration and frequently the amplitude of the follow-on current
[SOURCE: IEC 60050-614:2016, 614-03-51, modified ─ Addition of “to protect the electrical
apparatus from high transient overvoltages and”.]
3.3 Parts of switching devices
3.3.1
pole
<switching device> portion of a switching device associated exclusively with one electrically
separated conducting path of its main circuit and excluding those portions which provide a
means for mounting and operating all poles together
Note 1 to entry: A switching device is called single-pole if it has only one pole. If it has more than one pole, it can
be called multipole (two-pole, three-pole, etc.) provided the poles are or can be coupled in such a manner as to
operate together.
[SOURCE: IEC 60050-441:1984, 441-15-01]
3.3.2
main circuit
<switching device> all the conductive parts of a switching device included in the circuit which it
is designed to close or open
[SOURCE: IEC 60050-441:1984, 441-15-02]
3.3.3
control circuit
<switching device> all the conductive parts (other than the main circuit) of a switching device
which are included in a circuit used for the closing operation or opening operation, or both, of
the device
[SOURCE: IEC 60050-441:1984, 441-15-03]
3.3.4
auxiliary circuit
<switching device> all the conductive parts of a switching device which are intended to be
included in a circuit other than the main circuit and the control circuits of the device
Note 1 to entry: Some auxiliary circuits fulfil supplementary functions such as signalling, interlocking, etc., and, as
such, they can be part of the control circuit of another switching device.
[SOURCE: IEC 60050-441:1984, 441-15-04]
IEC 61095:2023 © IEC 2023 – 19 –
3.3.5
contact
<mechanical switching device> conductive parts designed to establish circuit continuity when
they touch and which, due to their relative motion during an operation, open or close a circuit
or, in the case of hinged or sliding contacts, maintain circuit continuity
[SOURCE: IEC 60050-441:1984, 441-15-05]
3.3.6
contact
contact piece
one of the conductive parts forming a contact
[SOURCE: IEC 60050-441:1984, 441-15-06]
3.3.7
main contact
contact included in the main circuit of a mechanical switching device, intended to carry, in the
closed position, the current of the main circuit
[SOURCE: IEC 60050-441:1984, 441-15-07]
3.3.8
auxiliary contact
contact included in an auxiliary circuit and mechanically operated by the switching device
[SOURCE: IEC 60050-441:1984, 441-15-10]
3.3.9
auxiliary switch
<mechanical switching device> switch containing one or more control and/or auxiliary contacts
mechanically operated by a switching device
[SOURCE: IEC 60050-441:1984, 441-15-11]
3.3.10
“a” contact
make contact
control or auxiliary contact which is closed when the main contacts of the mechanical switching
device are closed and open when they are open
[SOURCE: IEC 60050-441:1984, 441-15-12]
3.3.11
“b” contact
break contact
control or auxiliary contact which is open when the main contacts of the mechanical switching
device are closed and closed when they are open
[SOURCE: IEC 60050-441:1984, 441-15-13]
– 20 – IEC 61095:2023 © IEC 2023
3.3.12
release
<mechanical switching device> device, mechanically connected to a mechanical switching
device, which releases the holding means and permits the opening or the closing of the
switching device
Note 1 to entry: A release can have instantaneous, time-delay, etc. operation.
[SOURCE: IEC 60050-441:1984, 441-15-17]
3.3.13
actuating system
<mechanical switching device> whole of the operating means of a mechanical switching device
which transmits the actuating force to the contact pieces
Note 1 to entry: The operating means of an actuating system can be mechanical, electromagnetic, hydraulic,
pneumatic, thermal, etc.
3.3.14
actuator
part of the actuating system to which an external actuating force is applied
Note 1 to entry: The actuator can take the form of a handle, knob, push-button, roller, plunger, etc.
[SOURCE: IEC 60050-441:1984, 441-15-22]
3.3.15
position indicating device
part of a mechanical switching device which indicates whether it is in the open, closed, or,
where appropriate, earthed position
[SOURCE: IEC 60050-441:1984, 441-15-25]
3.3.16
terminal
conductive part of a device provided for electrical connection to external circuits
3.3.17
screw-type terminal
terminal intended for the connection and disconnection of conductors or for the interconnection
of two or more conductors, the connection being made, directly or indirectly, by means of screws
or nuts of any kind
3.3.18
screwless-type terminal
terminal intended for the connection and disconnection of conductors or for the interconnection
of two or more conductors, the connection being made, directly or indirectly, by means of
springs, wedges, eccentrics or cones, etc.
3.3.19
universal terminal
terminal for the connection and disconnection of all types of conductors (solid, stranded and
flexible)
[SOURCE: IEC 60998-2-2:2002, 3.101.1, modified – “(rigid and flexible)” replaced with “(solid,
stranded and flexible)”.]
IEC 61095:2023 © IEC 2023 – 21 –
3.3.20
non-universal terminal
terminal for the connection and disconnection of a certain kind of conductor only (for example,
solid conductors only or solid and stranded conductors only)
[SOURCE: IEC 60998-2-2:2002, 3.101.2, modified – “rigid [solid and stranded]” replaced with
“solid and stranded”.]
3.3.21
push-wire terminal
non-universal terminal in which the connection is made by pushing in solid or stranded
conductors
[SOURCE: IEC 60998-2-2:2002, 3.101.3, modified – “rigid (solid or stranded)” replaced with
“solid or stranded”.]
3.3.22
thread-forming tapping screw
tapping screw having an uninterrupted thread
Note 1 to entry: It is not a function of this thread to remove material from the hole.
Note 2 to entry: An example of a thread-forming tapping screw is shown in Figure 1.
3.3.23
thread-cutting tapping screw
tapping screw having an interrupted thread
Note 1 to entry: The thread is intended to remove material from the hole.
Note 2 to entry: An example of a thread-cutting tapping screw is shown in Figure 2.
3.3.24
clamping unit
part of a terminal necessary for the mechanical clamping and the electrical connection of the
conductor(s)
3.3.25
unprepared conductor
conductor which has been cut and the insulation of which has been removed for insertion into
a terminal
Note 1 to entry: A conductor, the shape of which is arranged for introduction into a terminal or the strands of which
are twisted to consolidate the end is considered to be an unprepared conductor.
3.3.26
prepared conductor
a conductor the end of which is fitted with an attachment such as eyelet, sleeve or cable lug
[SOURCE: IEC 60050-442:1998, 442-01-27]
– 22 – IEC 61095:2023 © IEC 2023
3.3.27
solid conductor
conductor consisting of a single wire
Note 1 to entry: The cross-section of the solid conductor can be circular or shaped.
Note 2 to entry: Solid conductor is defined as class 1 conductor in IEC 60228, or by IEC TR 60344, or equivalent
AWG/kcmil.
[SOURCE: IEC 60050-461:2008, 461-01-06, modified – In Note 1 to entry, “may” changed to
“can”, and Note 2 to entry has been added.]
3.3.28
stranded conductor
conductor consisting of a number of wires, all or some of which are wound in a helix
Note 1 to entry: Stranded conductor is defined as class 2 conductor in IEC 60228, or by IEC TR 60344, or equivalent
AWG/kcmil.
[SOURCE: IEC 60050-151:2001, 151-12-36, modified – Note 1 to entry has been added.]
3.3.29
rigid conductor
solid or stranded conductor having wires of such diameters, or so assembled, that the conductor
is not suitable for use in a flexible cable.
[SOURCE: IEC 60947-1:2020, 3.5.31]
3.3.30
flexible conductor
stranded conductor having wires of diameters small enough and so assembled that the
conductor is suitable for use in a flexible cable
Note 1 to entry: Flexible conductor is defined as class 5 or class 6 conductor in IEC 60228, or by IEC TR 60344, or
equivalent AWG/kcmil.
[SOURCE: IEC 60050-461:2008, 461-01-11, modified – Note 1 to entry has been added.]
3.4 Operation of switching devices
3.4.1
operation
<mechanical switching device> transfer of the moving contact(s) from one position to an
adjacent position
Note 1 to entry: For a circuit-breaker, this can be a closing operation or an opening operation.
Note 2 to entry: If distinction is necessary, an operation in the electrical sense, e.g. make or break, is referred to
as a switching operation, and an operation in the mechanical sense, e.g. close or open, is referred to as a mechanical
operation.
[SOURCE: IEC 60050-441:1984, 441-16-01]
3.4.2
operating cycle
<mechanical switching device> succession of operations from one position to another and back
to the first position through all other positions, if any
[SOURCE: IEC 60050-441:1984, 441-16-02]
IEC 61095:2023 © IEC 2023 – 23 –
3.4.3
operating sequence
<mechanical switching device> succession of specified operations with specified time intervals
[SOURCE: IEC 60050-441:1984, 441-16-03]
3.4.4
closing operation
<mechanical switching device> operation by which the device is brought from the open position
to the closed position
[SOURCE: IEC 60050-441:1984, 441-16-08]
3.4.5
opening operation
<mechanical switching device> operation by which the device is brought from the closed
position to the open position
[SOURCE: IEC 60050-441:1984, 441-16-09]
3.4.6
closed position
<mechanical switching device> position in which the predetermined continuity of the main circuit
of the device is secured
[SOURCE: IEC 60050-441:1984, 441-16-22]
3.4.7
open position
<mechanical switching device> position in which the predetermined dielectric withstand voltage
requirements are satisfied between open contacts in the main circuit of the device
Note 1 to entry: This definition differs from IEC 60050-441:1984, 441-16-23 to meet the requirements of dielectric
properties.
[SOURCE: IEC 60050-441:1984, 441-16-23, modified ─ Replacement of “clearance” with
“dielectric withstand voltage requirements are satisfied”.]
3.4.8
position of rest
<contactor> position which the moving elements of the contactor take up when its
electromagnet or its compressed-air device is not energized
[SOURCE: IEC 60050-441:1984, 441-16-24]
3.4.9
inching
jogging
energizing a motor or solenoid repeatedly for short periods to obtain small movements of the
driven mechanism
3.4.10
plugging
stopping or reversing a motor rapidly by reversing the motor primary connections while the
motor is running

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3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminology databases for use in standardization at the following 3.1 General terms 3.1.1 overcurrent current exceeding the rated current [SOURCE: IEC 60050-441:1984, 441-11-06] 3.1.2 short-circuit accidental or intentional conductive path between two or more conductive […]

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