IEC 60085:2004

Electrical insulation - Thermal classification

Gives guidance on the application of international standards in assigning a thermal class to electrical insulating materials (EIM) or simple combinations of such materials (IEC 60216-1), to electrical insulation systems (IEC 62114) and to insulation for electrical devices. This new edition distinguishes between thermal classes for electrical insulation systems and electrical insulating materials.

Isolation électrique - Classification thermique

Donne des lignes directrices concernant l'application de normes internationales dans l'attribution d'une classe thermique à des matériaux isolants électriques (MIE) ou à des combinaisons simples de tels matériaux (CEI 60216-1), des systèmes d'isolation électriques (CEI 62114) et l'isolation de dispositifs électriques. Cette nouvelle édition distingue les classes thermiques pour systèmes d'isolation électriques et matériaux isolants électriques.

General Information

• Status: Published
• Publication Date: 06-Jun-2004
• ICS: 17.220.99 - Other standards related to electricity and magnetism
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: TC 112 - Evaluation and qualification of electrical insulating materials and systems
• Drafting Committee: WG 6 - TC 112/WG 6
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 07-Nov-2007

Relations

• Revised: IEC 60085:2007 - Electrical insulation - Thermal evaluation and designation
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60085
Edition 3.0 2004-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation – Thermal classification

Isolation électrique – Classification thermique

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IEC 60085
Edition 3.0 2004-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation – Thermal classification

Isolation électrique – Classification thermique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
H
CODE PRIX
ICS 17.220.99; 29.035.01 ISBN 2-8318-7531-5

– 2 – 60085 © IEC:2004
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
ELECTRICAL INSULATION –
THERMAL CLASSIFICATION
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,
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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 60085 has been prepared by subcommittee 15E: Methods of test,
of IEC technical committee 15: Insulating materials.

This third edition cancels and replaces the second edition, published in 1984, and constitutes
a technical revision. This new edition distinguishes between thermal classes for electrical
insulation systems and electrical insulating materials.
The text of this standard is based on the following documents:
FDIS Report on voting
15E/232/FDIS 15E/237/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.

60085 © IEC:2004 – 3 –
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.
– 4 – 60085 © IEC:2004
ELECTRICAL INSULATION –
THERMAL CLASSIFICATION
1 Scope
This standard gives guidance on the application of international standards in assigning a
thermal class to electrical insulating materials (EIM) or simple combinations of such materials

(IEC 60216-1), to electrical insulation systems (IEC 62114) and to insulation for electrical

devices.
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 60216-1, Electrical insulating materials – Properties of thermal endurance – Part 1: Ageing
procedures and evaluation of test results
IEC 60216-5, Electrical insulating materials − Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60216-6, Electrical insulating materials − Thermal endurance properties – Part 6:
Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time
frame method
IEC 61857-1, Electrical insulation systems – Procedures for thermal evaluation – Part 1:
General requirements – Low-voltage
IEC 62114, Electrical insulation systems – Thermal classification
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply:
3.1
electrical insulating material

EIM
solid with negligibly low electric conductivity, or a simple combination of such materials, used
to separate conducting parts at different electrical potential in electrical devices
NOTE 1 In English, the term “insulating material” is sometimes used in a broader sense to designate also
insulating liquids and gases.
NOTE 2 For testing purposes, electrodes may be applied on material specimens without this combination formally
constituting an EIS to be tested as such.

60085 © IEC:2004 – 5 –
3.2
simple combination of electrical insulating materials

combination of EIM delivered in joint state for production of devices

NOTE For example a flexible material consisting of paper laminated on polyethylene terephthalate film

(IEC 60626) constitutes a “simple combination” in this sense. EIMs combined during the manufacturing process of
a device do not constitute “simple combinations” in this sense.

3.3
electrical insulation system
EIS
insulating structure containing one or more electrical insulating materials (EIMs) together with

associated conducting parts employed in an electrotechnical device
3.4
thermal class
designation of an EIM/EIS equal to the numerical value of the maximum used temperature in
degrees Celsius for which the EIM/EIS is appropriate
NOTE It may be necessary to assign different thermal classes to the same EIM/EIS for different service
conditions. The description of an electrotechnical product as being of a particular thermal class does not mean,
and must not be taken to imply that each insulating material used in its construction is of the same thermal
capability.
3.5
relative thermal endurance index
RTE
numerical value of the temperature in degrees Celsius at which the estimated time to endpoint
of the candidate material is the same as the estimated time to endpoint of the control material
at a temperature equal to its assessed thermal endurance (ATE)
3.6
assessed thermal endurance index
ATE
numerical value of the temperature in degrees Celsius, up to which the control material
possesses known, satisfactory service performance in the specified application
NOTE 1 The value of the ATE may vary between applications for the same material.
NOTE 2 Sometimes referred to as “absolute” thermal endurance index.
3.7
candidate material
material for which an estimate of the thermal endurance is required to be determined
NOTE The determination is made by simultaneous thermal ageing of the material and a control material.

3.8
control material
material with known thermal endurance, preferably derived from service experience, used for
comparative tests with the candidate material
4 Thermal endurance evaluation and classification
The thermal classification for insulation materials cannot be applied to an insulation system of
which they are components, unless the validity thereof is proved. Vice versa, the thermal
classification of a material cannot be deduced from the thermal class of an insulating system
of which it is a component.
– 6 – 60085 © IEC:2004
4.1 Electrical insulating materials (EIM)

Electrical insulating materials and simple combinations of insulating materials shall be

evaluated in accordance with IEC 60216-5 or IEC 60216-6 and refer to expected service

conditions.
4.2 Electrical insulation systems (EIS)

Electrical insulation systems shall be evaluated in accordance with IEC 61857-1 and

classified in accordance with IEC 62114.
...