IEC 61810-1:2008

IEC 61810-1
Edition 3.0 2008-02
INTERNATIONAL
STANDARD
Electromechanical elementary relays –
Part 1: General requirements
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IEC 61810-1
Edition 3.0 2008-02
INTERNATIONAL
STANDARD
Electromechanical elementary relays –
Part 1: General requirements
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
ICS 29.120.70 ISBN 2-8318-9586-3

– 2 – 61810-1 © IEC:2008(E)
CONTENTS
FOREWORD.5

1 Scope.7
2 Normative references .7
3 Terms and definitions .8
3.1 Definitions related to general terms .9
3.2 Definitions of relay types .9
3.3 Definitions related to conditions and operations.10
3.4 Definitions of operating values .12
3.5 Definitions related to contacts .13
3.6 Definitions related to accessories .16
3.7 Definitions related to insulation .16
4 Influence quantities .18
5 Rated values .18
5.1 Rated coil voltage/rated coil voltage range .18
5.2 Operative range .19
5.3 Release.19
5.4 Reset .19
5.5 Electrical endurance.19
5.6 Frequency of operation.19
5.7 Contact loads .20
5.8 Ambient temperature .20
5.9 Categories of environmental protection .20
5.10 Duty factor .20
6 General provisions for testing .20
7 Documentation and marking .22
7.1 Data .22
7.2 Additional data .23
7.3 Marking .23
7.4 Symbols .23
8 Heating .24
8.1 Requirements.24
8.2 Test procedure .25
8.3 Terminals .26
8.3.1 General .26
8.3.2 Solder terminals .26
8.3.3 Flat quick-connect terminations .26
8.3.4 Screw and screwless type terminals .27
8.3.5 Alternative termination types .27
8.3.6 Sockets .27
9 Basic operating function .27
9.1 General test conditions.27
9.2 Operate (monostable relays) .27
9.3 Release (monostable relays) .28
9.4 Operate/reset (bistable relays) .28
10 Insulation resistance and dielectric strength .28

61810-1 © IEC:2008(E) – 3 –
10.1 Preconditioning .28
10.2 Insulation resistance .28
10.3 Dielectric strength .28
11 Electrical endurance.30
12 Mechanical endurance.32
13 Clearances, creepage distances and solid insulation .32
13.1 General provisions .32
13.2 Clearances and creepage distances .33
13.3 Solid insulation.37
13.4 Accessible surfaces.37
14 Terminations .37
14.1 Screw terminals and screwless terminals .38
14.2 Flat quick-connect terminations .38
14.3 Solder terminals .38
14.3.1 Resistance to soldering heat .38
14.3.2 Solder pins .38
14.3.3 Terminals for surface mounting (SMD).38
14.3.4 Other solder terminations (e.g. soldering lugs) .38
14.4 Sockets .38
14.5 Alternative termination types .39
15 Sealing.39
16 Heat and fire resistance.39

Annex A (normative) Explanations regarding relays .40
Annex B (informative) Inductive contact loads.43
Annex C (normative) Test set-up .45
Annex D (informative) Special loads .49
Annex E (normative) Heating test arrangement.52
Annex F (normative) Measurement of clearances and creepage distances.53
Annex G (normative) Relation between rated impulse voltage, nominal voltage and
overvoltage category .59
Annex H (normative) Pollution degrees .60
Annex I (normative) Proof tracking test .61
Annex J (informative) Schematic diagram of families of terminations .62
Annex K (normative) Glow-wire test .63
Annex L (normative) Ball pressure test .64
Annex M (informative) Needle flame test.65

Alphabetical list of terms.66
Bibliography.67

Figure A.1 – Diagram explaining terms related to monostable relays .40
Figure A.2 – Example explaining terms relating to contacts.41
Figure A.3 – Explanations regarding the operative range of the coil voltage.41
Figure A.4 – Explanation regarding the preconditioning and testing of the operate
voltage according to 5.2.1 (Class 1) and 9.2 .42

– 4 – 61810-1 © IEC:2008(E)
Figure A.5 – Explanation regarding the preconditioning and testing of the operate
voltage according to 5.2.2 and 9.2 .42
Figure C.1 – Standard test circuit.45
Figure C.2 – Functional block diagram .46
Figure C.3 – Contact load categories .48
Figure D.1 – Circuit for cable load.49
Figure D.2 – Test circuit for inrush current loads (e.g. capacitive loads and simulated
tungsten filament lamp loads) – AC circuits.50
Figure D.3 – Example for a tungsten filament lamp test for relays rated 10/100 A/250
V~/2,5 ms .50
Figure D.4 – Test circuit for inrush current loads (e.g. capacitive loads and simulated
lamp loads) – DC circuits .51
Figure D.5 – Test circuit for inrush current loads (e.g. simulated fluorescent lamp
loads) with power-factor correction .51
Figure E.1 – Test arrangement .52
Figure J.1 – Schematic diagram of families of terminations.62
Figure L.1 – Ball pressure test apparatus.64

Table 1 – Reference values of influence quantities .18
Table 2 – Categories of protection .20
Table 3 – Type testing .21
Table 4 – Required relay data.22
Table 5 – Symbols .24
Table 6 – Examples for indication of rated values .24
Table 7 – Thermal classification.24
Table 8 – Cross-sectional areas and lengths of conductors dependent on the current
carried by the terminal .26
Table 9 – Minimum values of insulation resistance.28
Table 10 – Dielectric strength – AC.29
Table 11 – Dielectric strength – DC .30
Table 12 – Schematics for contact loading.31
Table 13 – Provisions for the dimensioning of clearances and creepage distances .34
Table 14 – Minimum clearances in air for insulation coordination .35
Table 15 – Material groups .35
Table 16 – Minimum creepage distances for equipment subject to long-term stresses .36
Table 17 – Rated insulation voltage according to supply system voltage.37
Table 18 – Test conditions for test Tb .38
Table B.1 – Verification of the making and breaking capacity (abnormal conditions) .43
Table B.2 – Verification of the making and breaking capacity (normal conditions) .44
Table B.3 – Electrical endurance test.44
Table C.1 – Characteristics of power sources for contact loads .46
Table C.2 – Standard contact load characteristics .47
Table G.1 – Rated impulse voltage for equipment energized directly from the low-
voltage mains .59

61810-1 © IEC:2008(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 1: General requirements
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
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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 61810-1 has been prepared by IEC technical committee 94: All-or-
nothing electrical relays.
This third edition cancels and replaces the second edition published in 2003. This edition
constitutes a technical revision.
The relevant modifications are:
– update of references;
– renumbering of clauses to bring them into a more logical order;
– inclusion of contact load categories (same as in IEC 61810-2 and IEC 61810-7);
– clarifications concerning electrical endurance (Clause 11);
– inclusion of provisions for insulation coordination in accordance with the basic safety
standards IEC 60664-3, IEC 60664-4 and IEC 60664-5 (Clause 13);

– 6 – 61810-1 © IEC:2008(E)
– renumbering of all annexes in the order they are referenced in the body of the standard;
– inclusion of new Annex C (normative) for the test set-up, and new Annex D (informative)
for special loads (based upon similar annexes in IEC 61810-2 and IEC 61810-7);
– improvement of Annex B covering inductive contact loads.

The text of this standard is based on the following documents:
FDIS Report on voting
94/267/FDIS 94/269/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of IEC 61810 series, published under the general title Electromechanical
elementary relays can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this document may be issued at a later date.
The contents of the corrigendum of February 2010 have been included in this copy.

61810-1 © IEC:2008(E) – 7 –
ELECTROMECHANICAL ELEMENTARY RELAYS –

Part 1: General requirements
1 Scope
This part of IEC 61810 applies to electromechanical elementary relays (non-specified time all-
or-nothing relays) for incorporation into equipment. It defines the basic functional
requirements and safety-related aspects for applications in all areas of electrical engineering
or electronics, such as:
• general industrial equipment,
• electrical facilities,
• electrical machines,
• electrical appliances for household and similar use,
• information technology and business equipment,
• building automation equipment,
• automation equipment,
• electrical installation equipment,
• medical equipment,
• control equipment,
• telecommunications,
• vehicles,
• transportation (e.g. railways).
Compliance with the requirements of this standard is verified by the type tests indicated.
In case the application of a relay determines additional requirements exceeding those
specified in this standard, the relay should be assessed in line with this application in
accordance with the relevant IEC standard(s) (e.g. IEC 60730-1, IEC 60335-1, IEC 60950-1).
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60038:1983, IEC standard voltages
Amendment 1 (1994)
Amendment 2 (1997)
IEC 60050, International Electrotechnical Vocabulary
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-17:1994, Basic environmental testing procedures – Part 2: Tests – Test Q:
Sealing
IEC 60068-2-20:1979, Basic environmental testing procedures – Part 2: Tests – Test T:
Soldering
Amendment 2 (1987)
IEC 60085:2004, Electrical insulation – Thermal classification

– 8 – 61810-1 © IEC:2008(E)
IEC 60112:2003, Method for the determination of the proof and the comparative tracking
indices of solid insulating materials
IEC 60364-4-44:2007, Low voltage electrical installations – Part 4-44: Protection for safety –
Protection against voltage disturbances and electromagnetic disturbances
IEC 60417:2007, Graphical symbols for use on equipment
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60664-3:2003, Insulation coordination for equipment within low-voltage systems – Part 3:
Use of coating, potting or moulding for protection against pollution
IEC 60664-4:2005, Insulation coordination for equipment within low-voltage systems – Part 4:
Consideration of high-frequency voltage stress
IEC 60664-5:2007, Insulation coordination for equipment within low-voltage systems – Part 5:
Comprehensive method for determining clearances and creepage distances equal to or less
than 2 mm
IEC 60695-2-10:2000, Fire hazard testing – Part 2-10: Glowing/hot-wire based test methods –
Glow-wire apparatus and common test procedure
IEC 60695-2-11:2000, Fire hazard testing – Part 2-11: Glowing/hot-wire based test methods –
Glow-wire flammability test method for end-products
IEC 60695-2-12:2000, Fire hazard testing – Part 2-12: Glowing/hot-wire based test methods –
Glow-wire flammability test method for materials
IEC 60695-2-13:2000, Fire hazard testing – Part 2-13: Glowing/hot-wire based test methods –
Glow-wire ignitability test method for materials
IEC 60695-10-2:2003, Fire hazard testing – Part 10-2: Abnormal heat – Ball pressure test
IEC 60721-3-3:2002, Classification of environmental conditions – Part 3-3: Classification of
groups of environmental parameters and their severities – Stationary use at weatherprotected
locations
Amendment 1 (1995)
Amendment 2 (1996)
IEC 60999-1:1999, Connecting devices – Electrical copper conductors – Safety requirements
for screw-type and screwless-type clamping units – Part 1: General requirements and
2 2
particular requirements for clamping units for conductors from 0,2 mm up to 35 mm
(included)
IEC 61210:1993, Connecting devices – Flat quick-connect terminations for electrical copper
conductors – Safety requirements
IEC 61760-1:2006, Surface mounting technology – Part 1: Standard method for the
specification of surface mounting components (SMDs)
IEC 61984:2001, Connectors – Safety requirements and tests
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050, in particular
IEC 60050-444 and the following apply.
An alphabetical list of terms can be found at the end of this standard.
NOTE In the text of this standard, the term relay is used instead of elementary relay to improve the readability.

61810-1 © IEC:2008(E) – 9 –
3.1 Definitions related to general terms
3.1.1
marking
identification of a relay which, when completely given to the manufacturer of this relay, allows
the unambiguous indication of its electrical, mechanical, dimensional and functional
parameters
EXAMPLE Through the indication of the trade mark and the type designation on the relay, all relay-specific data
can be derived from the type code.
3.1.2
intended use
use of a relay for the purpose for which it was made, and in the manner intended by the
manufacturer
3.1.3
relay technology categories
categorization of relays, based upon environmental protection
NOTE Six categories are in use (RT 0 to RT V).
[IEV 444-01-11, modified]
3.1.4
pulse width modulation
PWM
pulse time modulation in which the pulse duration varies in accordance with a given function
of the value of the modulating signal
[IEV 702-06-57]
3.2 Definitions of relay types
3.2.1
electrical relay
device designed to produce sudden and predetermined changes in one or more output circuits
when certain conditions are fulfilled in the electric input circuits controlling the device
[IEV 444-01-01]
NOTE 1 For the purpose of this standard, output circuits are contact circuits.
NOTE 2 For the purpose of this standard, the term “coil” is used to denote “input circuit”, although other types of
input circuits are possible.
3.2.2
all-or-nothing relay
electrical relay, which is intended to be energized by a quantity, the value of which is either
within its operative range or effectively zero
NOTE "All-or-nothing relays" include both "elementary relays" and "time relays".
[IEV 444-01-02]
3.2.3
elementary relay
all-or-nothing relay which operates and releases without any intentional time delay
[IEV 444-01-03, modified]
3.2.4
electromechanical relay
electrical relay in which the intended response results mainly from the movement of
mechanical elements
[IEV 444-01-04]
– 10 – 61810-1 © IEC:2008(E)
3.2.5
electromagnetic relay
electromechanical relay in which the designed response is produced by means of
electromagnetic forces
[IEV 444-01-05]
3.2.6
monostable relay
electrical relay which, having responded to an energizing quantity and having changed its
condition, returns to its previous condition when that quantity is removed
[IEV 444-01-07]
3.2.7
bistable relay
electrical relay which, having responded to an energizing quantity and having changed its
condition, remains in that condition after the quantity has been removed; a further appropriate
energization is required to make it change its condition
[IEV 444-01-08]
NOTE Bistable relays are also called latching relays.
3.2.8
polarized relay
electrical relay, the change of condition of which depends upon the polarity of its DC
energizing quantity
[IEV 444-01-09, modified]
3.2.9
non-polarized relay
electrical relay, the change of condition of which does not depend upon the polarity of its
energizing quantity
[IEV 444-01-10]
3.3 Definitions related to conditions and operations
3.3.1
release condition
for a monostable relay, specified condition of the relay when it is not energized; for a bistable
relay, one of the specified conditions, as declared by the manufacturer
[IEV 444-02-01]
NOTE See Figure A.1.
3.3.2
operate condition
for a monostable relay, specified condition of the relay when it is energized by the specified
energizing quantity and has responded to that quantity; for a bistable relay, the condition
other than the release condition as declared by the manufacturer
[IEV 444-02-02]
NOTE See Figure A.1.
3.3.3
operate (verb)
change from the release condition to the operate condition
[IEV 444-02-04]
NOTE See Figure A.1.
61810-1 © IEC:2008(E) – 11 –
3.3.4
release (verb)
for a monostable relay, change from the operate condition to the release condition
[IEV 444-02-05]
NOTE See Figure A.1.
3.3.5
reset (verb)
for a bistable relay, change from the operate condition to the release condition
[IEV 444-02-06]
3.3.6
cycle
operation and subsequent release/reset
[IEV 444-02-11]
3.3.7
frequency of operation
number of cycles per unit of time
[IEV 444-02-12]
3.3.8
continuous duty
duty in which the relay remains energized for a period long enough to reach thermal
equilibrium
[IEV 444-02-13]
3.3.9
intermittent duty
duty in which the relay performs a series of identical cycles, the durations in the energized
and unenergized conditions being specified; the duration of energization of the relay is such
as will not permit the relay to reach thermal equilibrium
[IEV 444-02-14, modified]
3.3.10
temporary duty
duty in which the relay remains energized for insufficient duration to reach thermal
equilibrium, the time intervals of energization being separated by unenergized time intervals
of duration sufficient to restore equality of temperature between the relay and the surrounding
medium
[IEV 444-02-16]
3.3.11
duty factor
ratio of the duration of energization to the total period in which intermittent or continuous or
temporary duty takes place
NOTE The duty factor can be expressed as a percentage of the total period.
[IEV 444-02-15]
3.3.12
thermal resistance (of the coil)
quotient of the temperature rise of the relay coil by the input power, measured after a period
long enough to reach thermal equilibrium
NOTE The thermal resistance usually is given in K/W.

– 12 – 61810-1 © IEC:2008(E)
[IEV 444-02-17]
3.3.13
ambient temperature
temperature(s) prescribed for the air surrounding the relay under certain conditions, when the
relay is mounted as indicated by the manufacturer
3.3.14
limiting continuous thermal withstand power
highest steady state value of the applied electric power that a relay can withstand
continuously, and under specified conditions, while satisfying specified temperature rise
requirements
[IEV 444-03-18, modified]
NOTE Comprises both the applied power at the coil(s) and the contact(s).
3.3.15
thermal equilibrium
variation of less than 1 K between any two out of three consecutive measurements made at
an interval of 5 min
3.3.16
rated value
value of a quantity used for specification purposes, established for a specific set of operating
conditions
[IEV 444-02-18, modified]
3.3.17
test value
value of a quantity for which the relay shall comply with a specified action during a test
[IEV 444-02-20]
3.3.18
actual value
value of a quantity determined by measurement on a specific relay, during performance of a
specified function
[IEV 444-02-21]
3.3.19
mechanical endurance
number of cycles under specified conditions with unloaded contact(s)
[IEV 444-07-10, modified]
3.4 Definitions of operating values
3.4.1
energizing quantity
electrical quantity which, when applied to the coil(s) of a relay under specified conditions,
enables it to fulfil its purpose
NOTE For relays, the energizing quantity is usually a voltage. Therefore, the input voltage as energizing quantity
is used in the definitions given in 3.4. Where a relay is energized by a given current instead, the respective terms
and definitions apply with "current" used instead of "voltage".
[IEV 444-03-01, modified]
3.4.2
operate voltage
set voltage (for bistable relays only)
value of the coil voltage at which a relay operates

61810-1 © IEC:2008(E) – 13 –
[IEV 444-03-06, modified]
3.4.3
operate voltage
U
value of the coil voltage at which a relay operates, having previously been energized at that
same voltage
NOTE Thermal equilibrium has to be achieved.
3.4.4
limiting voltage
U
value of the coil voltage, taking into account the effect of heating due to the power dissipated
by the coil(s), which when exceeded may result in a relay failure caused by thermal overload
NOTE Thermal equilibrium has to be achieved.
3.4.5
operative range
range of values of coil voltage for which a relay is able to perform its specified function
[IEV 444-03-05, modified]
3.4.6
release voltage
value of the coil voltage at which a monostable relay releases
[IEV 444-03-08, modified]
3.4.7
reset voltage
value of the coil voltage at which a bistable relay resets
[IEV 444-03-10, modified]
3.5 Definitions related to contacts
For a.c., r.m.s. values for voltage and current are specified, unless otherwise indicated.
3.5.1
contact
arrangement of contact members, with their insulation, which close or open their contact
circuit by their relative movement (see Figure A.2)
[IEV 444-04-03]
3.5.2
contact set
combination of contacts within a relay, separated by their insulation (see Figure A.2)
[IEV 444-04-04]
3.5.3
contact gap
gap between the contact points when the contact circuit is open
[IEV 444-04-09]
3.5.4
make contact
contact which is closed when the relay is in its operate condition and which is open when the
relay is in its release condition
[IEV 444-04-17]
– 14 – 61810-1 © IEC:2008(E)
3.5.5
break contact
contact which is open when the relay is in its operate condition and which is closed when the
relay is in its release condition
[IEV 444-04-18]
3.5.6
change-over contact
combination of two contact circuits with three contact members, one of which is common to
the two contact circuits; such that when one of these contact circuits is open, the other is
closed
[IEV 444-04-19]
3.5.7
switching power
power which a relay contact makes and/or breaks
NOTE The switching power is usually specified in W for d.c. and in VA for a.c.
[IEV 444-04-24]
3.5.8
switching voltage
voltage between the contact members before closing or after opening of a relay contact
NOTE The term “contact voltage” (see IEV 444-04-25) has been replaced by “switching voltage”. The definition
remains unchanged, however.
3.5.9
contact current
electric current which a relay contact carries before opening or after closing
[IEV 444-04-26]
3.5.10
switching current
electric current which a relay contact makes and/or breaks
[IEV 444-04-27]
3.5.11
limiting continuous current
greatest value of electric current which a closed contact is capable of carrying continuously
under specified conditions
[IEV 444-04-28, modified]
3.5.12
limiting short-time current
greatest value of electric current which a closed contact is capable of carrying for a specified
short period under specified conditions
[IEV 444-04-29, modified]
3.5.13
limiting making capacity
greatest value of electric current which a contact is capable of making under specified
conditions such as switching voltage, number of makes, power factor, time constant
[IEV 444-04-30, modified]
61810-1 © IEC:2008(E) – 15 –
3.5.14
limiting breaking capacity
greatest value of electric current which a contact is capable of breaking under specified
conditions such as switching voltage, number of breaks, power factor, time constant
[IEV 444-04-31, modified]
3.5.15
limiting cycling capacity
greatest value of electric current which a contact is capable of making and breaking
successively under specified conditions such as switching voltage, number of breaks, power
factor, time constant
[IEV 444-04-32, modified]
3.5.16
micro-interruption
interruption of a circuit by contact separation which does not provide full-disconnection or
micro-disconnection
NOTE There are no dielectric strength or dimensional requirements for the contact gap.
[IEC 60730-1, 2.4.4, modified]
3.5.17
micro-disconnection
adequate contact separation in at least one contact so as to provide functional security
NOTE There is a requirement for the dielectric strength of the contact gap but no dimensional requirement.
[IEC 60730-1, 2.4.3, modified]
3.5.18
full-disconnection
contact separation for the disconnection of conductors so as to provide the equivalent of basic
insulation between those parts intended to be disconnected
NOTE There are dielectric strength and dimensional requirements.
[IEC 60730-1, 2.4.2, modified]
3.5.19
all-pole disconnection
full-disconnection of all conductors by a single switching action
3.5.20
failure
termination of the ability of an item to perform a required function
[IEV 191-04-01]
NOTE For the purpose of this standard, items are elementary relays.
3.5.21
malfunction
single event when an item does not perform a required function
3.5.22
contact failure
occurrence of break and/or make malfunctions of a contact under test, exceeding a specified
number
3.5.23
electrical endurance
number of cycles without contact failure under specified conditions, with loaded contacts

– 16 – 61810-1 © IEC:2008(E)
3.6 Definitions related to accessories
3.6.1
manual operation
manual movement of the actuating member of the relay
3.6.2
actuating member
part which is pulled, pushed, turned or otherwise operated in order to initiate a function
3.6.3
switching position indicator
part of a relay for visual indication of the switching position
3.7 Definitions related to insulation
3.7.1
functional insulation
insulation between conductive parts which is necessary only for the proper functioning of the
relay
[IEC 60664-1, 1.3.17.1, modified]
3.7.2
basic insulation
insulation applied to live parts to provide basic protection against electric shock
NOTE Basic insulation does not necessarily include insulation used exclusively for functional purposes.
[IEC 60664-1, 1.3.17.2]
3.7.3
supplementary insulation
independent insulation applied in addition to basic insulation, in order to provide protection
against electric shock in the event of a failure of basic insulation
[IEC 60664-1, 1.3.17.3]
3.7.4
double insulation
insulation comprising both basic insulation and supplementary insulation
[IEC 60664-1, 1.3.17.4]
3.7.5
reinforced insulation
a single insulation system applied to live parts, which provides a degree of protection against
electric shock equivalent to double insulation
[IEC 60664-1, 1.3.17.5, modified]
3.7.6
conductive part
part which is capable of conducting electric current, although it may not necessarily be used
for this purpose
3.7.7
live part
conductor or conductive part intended to be energized in normal operation, including a neutral
conductor, but by convention not a PEN conductor
[IEV 195-02-19, modified]
NOTE A PEN conductor combines the functions of both a protective earthing conductor and a neutral conductor.

61810-1 © IEC:2008(E) – 17 –
3.7.8
clearance
shortest distance in air between two conductive parts, or between a conductive part and the
accessible surface of a relay
[IEC 60664-1, 1.3.2, modified]
NOTE An example for an accessible surface is the actuating member of a relay used for manual operation.
3.7.9
solid insulation
solid insulating material interposed between two conductive parts
[IEC 60664-1, 1.3.4]
3.7.10
supporting material
solid insulating material keeping live parts in their position
3.7.11
creepage distance
shortest distance along the surface of the insulating material between two conductive parts
[IEC 60664-1, 1.3.3]
3.7.12
tracking
progressive degradation of a solid insulating material by local discharges to form conducting
or partially conducting paths
NOTE Tracking usually occurs due to surface contamination.
[IEV 212-01-42, modified]
3.7.13
proof tracking index
PTI
numerical value of the proof voltage expressed in volts which a material
...