IEC TR 63040:2016

Guidance on clearances and creepage distances in particular for distances equal to or less than 2 mm - Test results of research on influencing parameters

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.

General Information

• Status: Published
• Publication Date: 25-Sep-2016
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.080.30 - Insulation systems
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: TC 109 - Insulation co-ordination for low-voltage equipment
• Current Stage: PPUB - Publication issued
• Start Date: 31-Dec-2016
• Completion Date: 26-Sep-2016

Relations

• Corrected By: IEC TR 63040:2016/COR1:2019 - Corrigendum 1 - Guidance on clearances and creepage distances in particular for distances equal to or less than 2 mm - Test results of research on influencing parameters
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TR 63040 ®
Edition 1.0 2016-09
TECHNICAL
REPORT
colour
inside
Guidance on clearances and creepage distances in particular for distances
equal to or less than 2 mm – Test results of research on influencing parameters

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IEC TR 63040 ®
Edition 1.0 2016-09
TECHNICAL
REPORT
colour
inside
Guidance on clearances and creepage distances in particular for distances

equal to or less than 2 mm – Test results of research on influencing parameters

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.30 ISBN 978-2-8322-3656-7

– 2 – IEC TR 63040:2016 © IEC 2016
CONTENTS
FOREWORD .4
INTRODUCTION .6
1 Scope .7
2 Normative references .7
3 Terms and definitions .7
4 Fundamental aspects and phenomena of clearance and creepage distances .9
4.1 Mutual correlation of insulation characteristics with regard to environmental
conditions .9
4.2 Pollution .9
4.2.1 General .9
4.2.2 Humidity level (HL) . 10
4.2.3 Relation of humidity levels to macro-environment . 10
4.2.4 Comparative tracking index (CTI) . 11
4.2.5 Flashover characteristics . 11
5 Clearances and creepage distances . 12
5.1 General . 12
5.2 Clearances . 12
5.2.1 Influencing criteria . 12
5.2.2 Altitude . 14
5.3 Creepage distances . 16
5.3.1 General . 16
5.3.2 Influencing factors . 16
5.3.3 Dimensioning of creepage distances of functional insulation . 22
6 Additional information regarding creepage distance characteristics – surface
current over a creepage distance (minimum insulation resistance) . 22
7 Water adsorption test . 24
7.1 Object . 24
7.2 Withstand characteristics of creepage distances under high humidity . 24
7.3 Recommended test method . 25
7.3.1 Test specimen . 25
7.3.2 Measurement of the impulse withstand voltage . 25
7.3.3 Procedure for characterization of the insulating materials . 25
7.4 Definitions of the water adsorption groups . 26
8 Dimensioning diagrams . 28
9 Withstand voltage test for creepage distance under humidity conditions . 32
Bibliography . 33

Figure 1 – Clearances in air for mutual correlation of insulation characteristics to
withstand transient overvoltages up to 2 000 m above sea level . 14
Figure 2 – Creepage distances for mutual correlation of insulation characteristics to
avoid failure due to tracking . 19
Figure 3 – Creepage distances for mutual correlation of insulation characteristics to
avoid flashover. 21
Figure 4 – Creepage distances required to maintain minimum insulation resistance . 24
Figure 5 – Layout of the test specimen. 27

Figure 6 – Test circuit . 27
Figure 7 – Critical relative humidity of insulating materials . 28
Figure 8 – Diagram for dimensioning of clearances ≤ 2 mm for circuits directly
connected to the supply mains (for low-voltage equipment up to 2 000 m) . 29
Figure 9 – Diagram for dimensioning of clearances ≤ 2 mm for circuits not directly
connected to the supply mains (for low-voltage equipment up to 2 000 m) . 30
Figure 10 – Diagram for dimensioning of creepage distances ≤ 2 mm (for low-voltage
equipment up to 2 000 m) . 31
Figure 11 – Withstand voltage test for creepage distance under humidity conditions. 32

Table 1 – Relation of the humidity levels to macro-environments . 10
Table 2 – Clearances for mutual correlation of insulation characteristics to withstand
transient overvoltages . 13
Table 3 – Clearances to withstand steady-state voltages, temporary overvoltages or
recurring peak voltages . 15
Table 4 – Creepage distances for mutual correlation of insulation characteristics in
equipment to avoid failure due to tracking . 18
Table 5 – Creepage distances for mutual correlation of insulation characteristics to
avoid flashover. 20
Table 6 – Minimum insulation resistance . 22
Table 7 – Creepage distances to maintain minimum insulation resistance (without
condensation) . 23

– 4 – IEC TR 63040:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE ON CLEARANCES AND CREEPAGE
DISTANCES IN PARTICULAR FOR DISTANCES EQUAL
TO OR LESS THAN 2 mm – TEST RESULTS OF RESEARCH
ON INFLUENCING PARAMETERS
FOREWORD
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