TC 109 - Insulation co-ordination for low-voltage equipment

IEC 60664-1:2020 deals with insulation coordination for equipment having a rated voltage up to AC 1 000 V or DC 1 500 V connected to low-voltage supply systems. This document applies to frequencies up to 30 kHz. It applies to equipment for use up to 2 000 m above sea level and provides guidance for use at higher altitudes. It provides requirements for technical committees to determine clearances, creepage distances and criteria for solid insulation. It includes methods of electrical testing with respect to insulation coordination. The minimum clearances specified in this document do not apply where ionized gases are present. Special requirements for such situations can be specified at the discretion of the relevant technical committee. This document does not deal with distances:
– through liquid insulation;
– through gases other than air;
– through compressed air.
This edition includes the following significant technical changes with respect to the previous edition:
update of the Scope, Clauses 2 and 3,
addition of 1 500 V DC into tables,
new structure for Clauses 4 and 5,
addition of Annex G with a flowchart for clearances,
addition of Annex H with a flowchart for creepage distances,
update of distances altitude correction in a new Table F.10.
It has the status of a basic safety publication in accordance with IEC Guide 104.
The contents of the corrigendum of October 2020 have been included in this copy.

IEC TS 62993:2017 gives guidance to technical committees which deal with equipment having a rated voltage of more than 1 000 V AC and up to 2 000 V AC, or a rated voltage of more than 1 500 V DC and up to 3 000 V DC. Rated voltages up to 1 000 V AC and 1 500 V DC, as well as higher or lower internal voltages, are covered by IEC 60664-1.
This document applies to equipment for use up to 2 000 m above sea level, and provides guidance for use at higher altitudes.
This document gives guidance for clearances, creepage distances and solid insulation for equipment to achieve safety. It includes methods of electric testing.
The contents of the corrigendum of June 2018 have been included in this copy.

IEC 60664-3:2016 applies to assemblies protected against pollution by the use of coating, potting or moulding, thus allowing a reduction of clearance and creepage distances as described in IEC 60664-1. This document describes the requirements and test procedures for two methods of protection:
- type 1 protection improves the microenvironment of the parts under the protection;
- type 2 protection is considered to be similar to solid insulation. This edition includes the following significant technical changes with respect to the previous edition:
a) information added concerning interpolation;
b) provided scratch test is only for type 2 protection;
c) renumbered the scratch test to follow the visual examination test, since it makes more sense there;
d) separated the tables under what is now called Annex A, to make them clearer.

IEC TR 63040:2016(E) describes test results of research on dimensioning of clearances and creepage distances, for spacing equal to or less than 2 mm for printed wiring material and other equivalent arrangements of insulation, where the clearance and the creepage distance follows the same path along the surface of solid insulation. The information contained in this document is the result of research only and cannot be used for dimensioning the clearances and creepage distances for equipment within low-voltage systems, where IEC 60664-1 applies. However distances can be taken into account for functional reasons. This document provides results of research related to the following criteria:
1) clearances independent from the micro-environment;
2) creepage distances for pollution degree 1, 2 and 3 which extends the use of smaller distances to products having design features similar to printed circuit boards;
3) creepage distances to avoid flashover of the insulating surface;
4) information on minimum creepage distances to maintain minimum insulation resistance.
A test method for the evaluation of the relevant water adsorption group for the surface of any insulating material which has not yet been classified is described.
The contents of the corrigendum of January 2019 have been included in this copy.

IEC/TR 60664-2-1:2011, which is a technical report, serves as an application guide for technical committees and manufacturers specifying dimensioning requirements for products in accordance with the IEC 60664 series. The significant items for consideration are as follows:
a) nominal system voltage(s) or rated insulation voltage(s);
b) overvoltage category of the products (OV cat.);
c) any type of overvoltages;
d) frequency of the voltage;
e) characteristics of the solid insulating material;
f) pollution degree and humidity levels.
The main changes with respect to the previous edition are listed below:
- the previous edition was only an application guide for IEC 60664-1. This second edition takes into account not only IEC 60664-1 but also the other parts IEC 60664-3, IEC 60664-4, and IEC 60664-5 and their interrelation;
- principles of the IEC 60664 series for insulation dimensioning of LV equipment are explained and examples of practical application are provided together with some background information;
- Annex A provides an overview of clauses of IEC 60664-1 requiring decisions by technical committees, or specification of options, or requiring activities of the manufacturer;
- Annex B provides an overview of such clauses of IEC 60664-4;
- Annex C provides an overview of such clauses of IEC 60664-5;
- Annex D amends the tables of Annex F of IEC 60664-1:2007 with rated impulse voltages for voltages line to neutral derived from nominal d.c. voltages up to and including 1 500 V.
The contents of the corrigendum of October 2011 have been included in this copy.

The contents of the corrigendum of November 2010 have been included in this copy.

IEC 60664-1:2007 Deals with insulation coordination for equipment within low-voltage systems. It applies to equipment for use up to 2 000 m above sea level having a rated voltage up to a.c. 1 000 V with rated frequencies up to 30 kHz, or a rated voltage up to d.c. 1 500 V. It specifies the requirements for clearances, creepage distances and solid insulation for equipment based upon their performance criteria. It includes methods of electric testing with respect to insulation coordination. The minimum clearances specified in this standard do not apply where ionized gases occur. Special requirements for such situations may be specified at the discretion of the relevant technical committee. This standard does not deal with distances:
- through liquid insulation,
- through gases other than air,
- through compressed air.
Main changes have been made with respect to the previous edition:
- Amendment of Japanese mains conditions with regard to the rated impulse voltages, the rationalized voltages and the nominal voltages of supply systems for different modes of overvoltage control
- Amendment of dimensioning of clearances smaller than 0,01 mm
- Alignment of the table and the corresponding formula regarding test voltages for verifying clearances at different altitudes
- Amendment of interpolation of the creepage distance values for functional insulation
- Amendment of creepage distance dimensioning taking into account ribs
- Revision of the former Clause 4 "Tests and measurements" (now Clause 6) to achieve a more detailed description of the tests and their purpose, the test equipment and possible alternatives
- Change of Annex C "Partial discharge test methods" from a former technical report, Type 2 (now called TS), to a normative Annex C.

IEC 60664-4:2005 Deals with basic, supplementary and reinforced insulation subjected to high-frequency voltage stress within low-voltage equipment. The dimensioning values directly apply for basic insulation; for reinforced insulation additional requirements apply according to Part 1. It is applicable for the dimensioning of clearances, creepage distances and solid insulation stressed by any type of periodic voltages with a fundamental frequency above 30 kHz and up to 10 MHz. This part of IEC 60664 can only be used together with IEC 60664-1 or with IEC 60664-5 (in this standard called Part 1 or Part 5). By using Part 1 or Part 5 together with this part the frequency limit of Part 1 or Part 5 is extended to frequencies higher than 30 kHz. This part also applies to Part 3 for frequencies greater than 30 kHz and protection of type 1. For type 2 protection this question is under consideration. Applies to equipment for use up to 2 000 m above sea level having a rated voltage up to a.c. 1 000 V. Specifies the requirements for clearances, creepage distances and solid insulation for equipment based upon their performance criteria. lt includes methods of electric testing with respect to insulation coordination. The minimum clearances specified in this part do not apply where ionized gases occur. Special requirements for such situations may be specified at the discretion of the relevant technical committee. This part does not deal with distances
- through liquid insulation,
- through gases other than air,
- through compressed air.
The object of this standard is to guide technical committees responsible for different equipment in order to rationalise their requirements so that insulation coordination is achieved when specifying clearances in air, creepage distances and solid insulation for equipment. The major changes made during the revision of IEC 60664-4 were the following:
- inclusion of more recent information about the withstand characteristics of insulation at high-frequency voltage stress (see Annexes A, B and C);
- inclusion of requirements for the dimensioning of clearances at high-frequency voltage stress (see Clause 4);
- inclusion of requirements for the dimensioning of creepage distances at high-frequency voltage stress (see Clause 5);
- inclusion of requirements for the dimensioning of solid insulation at high-frequency voltage stress (see Clause 6);
- inclusion of diagrams to provide guidance on dimensioning with respect to high-frequency voltage stress (see Annex F);
specification of tests with respect to high-frequency voltage stress (see Clause 7);
- inclusion of test circuits for high-frequency voltage withstand testing and partial discharge testing (see Annex D.1 and D.2.1);
- inclusion of design criteria for partial discharge test circuits at high-frequency voltage (see Annex D.2.2);
- inclusion of criteria for dealing with non sinusoidal voltage stress (see Clause 8 and Annex E).

Specifies the dimensioning of clearances and creepage distances for spacings equal to or less than 2 mm for printed wiring board and equivalent constructions, where the clearance and the creepage distance are identical and are along the surface of solid insulation, such as the paths described in example 1, example 5 and example 11 of 4.2 of Part 1. The dimensioning is more precise than that provided by Part 1 (i.e IEC 60664-1). This standard can only be used as an entirety. It is not permitted to select one or more clauses from this standard and to use them in place of the corresponding clauses of Part 1. When this standard is applied to the dimensioning of clearances and creepage distances, all clauses shall be used in place of the corresponding clauses given in Part 1. For clearances and creepage distances larger than 2 mm and for solid insulation in general, Part 1 applies. This standard is based on the following criteria for dimensioning: - minimum clearances independent of the micro-environment (see Table 2); - minimum creepage distances for pollution degrees 1, 2 and 3 to avoid failure due to tracking (see Table 4); - minimum creepage distances to avoid flashover across the insulating surface (see Table 5). A test method is specified for allocating unclassified insulating material to the relevant water adsorption group. Has the status of a basic safety publication in accordance with IEC Guide 104.

Applies to assemblies protected against pollution by the use of coating, potting or moulding, thus allowing a reduction of clearance and creepage distances as described in Part 1 or Part 5. This standard describes the requirements and test procedures for two methods of protection: - type 1 protection improves the microenvironment of the parts under the protection; - type 2 protection is considered to be similar to solid insulation. This standard also applies to all kinds of protected printed boards, including the surface of inner layers of multi-layer boards, substrates and similarly protected assemblies. In the case of multi-layer printed boards, the distances through an inner layer are covered by the requirements for solid insulation in Part 1. This standard refers only to permanent protection. It does not cover assemblies that are subjected to mechanical adjustment or repair. The principles of this standard are applicable to functional, basic, supplementary and reinforced insulation. Has the status of a basic safety publication in accirdance with IEC Guide 104. The major changes made during the revision of IEC 60664-3 were the following: - Part 3 has been exactly aligned with Part 1 (including amendments 1 and 2). It has been made clear that Part 3 can only be used as a whole document together with Part 1 of IEC 60664. - The scope of Part 3 has been greatly extended including now also potting and moulding and similar procedures providing protection against pollution. The standard also applies to all kinds of coated printed boards including the surface of inner-layers of multi-layer boards, substrates and similar protected assemblies. The distances through an inner layer of multi-layer boards however are covered by the requirements for solid insulation in Part 1. - The difference between the two types of protection has been clarified. Type 1 (formerly type A) protection leads to a reduction of the pollution degree present beyond the protection to pollution degree 1. Type 2 (formerly type B) protection introduces protection systems which can be considered similar to solid insulation. Consequently the dimensioning and test requirements have been aligned more correctly. - The area of application has been extended including now functional, basic, supplementary and reinforced insulation. - Type 1 and type 2 protection now can both be used under the conditions of pollution degree 3 (formerly only type B). - Not only type 2 protection but also type 1 protection requires that between two conductive parts 100 % of the distance across the spacing shall be covered by the protection. - For type 2 protection minimum distances have been introduced. In any case the spacings shall not be lower than the minimum value of 10 µm. - Also the new Part 5 of IEC 60664 is referred to. - The tests follow much more closely the different requirements for type 1 and type 2 protection. The protected assembly shall withstand the electrical tests for solid insulation in 4.1.2 of IEC 60664-1. For type 1 protection, the partial discharge test is not applicable. For type 2 protection, the partial discharge test is required. The required partial discharge extinction voltage and the test method are specified in 4.1.2.4 of IEC 60664-1. - The requirements for the test specimen have been aligned with the extended scope. - The tests for the "adhesion of coating" and the "scratch resistance test" have been updated.

Specifies the requirements for clearances, creepage distances and solid insulation for equipment based upon their performance criteria. Applies to equipment for use up to 2 000 m above sea level having a rated voltage up to 1 000 V a.c. with rated frequencies up to 30 kHz or a rated voltage up to 1 500 V d.c. Supersedes IEC 664 and IEC 664A. Has the status of a basic safety publication in accordance with IEC Guide 104.

IEC TR 60664-2-2:2002(E) Provides an overview of the different kinds of surge overvoltages that can occur on low-voltage installations and equipment. In particular:
- the magnitude and duration of typical surges as well as their frequency of occurrence;
- information on overvoltages resulting from interaction between power and communication systems;
- guidelines when considering interface issues in relation to insulation coordination;
- guidelines concerning surge protection means on the basis of availability and risk considerations, including interaction within the system;
- highlights temporary overvoltages and other factors that have to be taken into account for insulation coordination, primarily related to protective control using surge protective devices.

A guide for technical committees specifying dimensioning requirements for products in accordance with IEC 60664-1. Significant items covered are as follows: a) nominal system voltage(s) or rated insulation voltage(s); b) overvoltage category of the products; c) pollution degree. A diagram for dimensioning of clearances and creepage distances for low-voltage equipment (up to 2 000 m) is also given. This is a technical report - type 3. Has the status of a basic safety publication in accordance with IEC Guide 104. This application guide is only applicable to IEC 60664-1 Ed.1 (1992).

This technical report of type 3 deals with insulation subjected to high frequency voltage stress within low-voltage equipment. Steady-state voltages with frequencies up to 100 MHz are considered. It has the status of a basic safety publication in accordance with IEC Guide 104.

Specifies the dimensioning of clearances and creepage distances for spacings equal to or less than 2 mm for printed wiring board and equivalent constructions, where the clearance and the creepage distance are identical and are along the surface of solid insulation. The dimensioning in this standard is more precise than that provided by IEC 60664-1. However, if the precision provided by this standard is not required, IEC 60664-1 may be applied instead. This standard is based on the following criteria for dimensioning: - minimum clearances independent of the micro-environment; - minimum creepage distances for pollution degrees 1, 2 and 3 to avoid failure due to tracking; - minimum creepage distances to avoid flashover across the insulating surface. A test method is specified for allocating unclassified insulating material to the relevant water adsorption group. The following major technical changes are: - Amendment of Japanese mains conditions with regard to the rated impulse voltages, the rationalized voltages and the nominal voltages of supply systems for different modes of overvoltage control. - Amendment of dimensioning of clearances smaller than 0,01 mm. Alignment of the table and the corresponding formula regarding test voltages for verifying clearances at different altitudes. - Amendment of interpolation of the creepage distance values for functional insulation. - Revision of the former Clause 4 "Tests and measurements" (now Clause 6) to achieve a more detailed description of the tests and their purpose, the test equipment and possible alternatives. Has the status of a basic safety publication in accordance with IEC Guide 104.