IEC 60068-2-78:2025

IEC 60068-2-78 ®
Edition 3.0 2025-08
INTERNATIONAL
STANDARD
REDLINE VERSION
Environmental testing -
Part 2-78: Tests - Test Cab: Damp heat, steady state
ICS 19.040; 29.020 ISBN 978-2-8327-0641-1
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CONTENTS
FOREWORD . 2
INTRODUCTION . 4
1 Scope and object . 5
2 Normative references . 5
3 Terms and definitions . 5
4 General test procedure . 5
4.1 General . 5
4.2 Description of test chamber and measuring system . 6
4.3 Severity . 7
4.4 Pre-conditioning . 8
4.5 Testing procedure . 9
4.6 Recovery procedure . 12
5 Measurements . 12
5.1 Initial measurements . 12
5.2 Intermediate measurements . 12
5.3 Final measurements. 12
6 Information to be given in the relevant specification . 12
7 Information to be given in the test report . 13
Bibliography . 14

Figure 1 – Examples of pre-conditioning phases with transition to the conditioning
periods for a) Method II and b) Method IV . 8
Figure 2 – Test Cab – Method I . 10
Figure 3 – Test Cab – Method II . 10
Figure 4 – Test Cab – Method III . 11
Figure 5 – Test Cab – Method IV . 11

Table 1 – Preferred values for the temperature and relative humidity . 7

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Environmental testing -
Part 2-78: Tests - Test Cab: Damp heat, steady state

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC 60068-2-78:2012. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.

IEC 60068-2-78 has been prepared by technical committee 104: Environmental conditions,
classification, and methods of test. It is an International Standard.
This third edition cancels and replaces the second edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) revision of the requirements for the test chamber;
b) revision of the severities and including the dew point temperatures;
c) change of the temperature tolerances of the test to limits;
d) inclusion of a specified preconditioning procedure;
e) inclusion of a new figure for clarification purposes;
f) revision of standardized requirements for the test report.
The text of this International Standard is based on the following documents:
Draft Report on voting
104/1109/FDIS 104/1126/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all the parts in the IEC 60068 series, under the general title Environmental testing, can
be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
This part of IEC 60068 provides a test method of high humidity at constant temperature without
condensation on the specimen over a prescribed specified period. This test is performed to
evaluate the specimen as it is influenced by the absorption and diffusion of moisture and
moisture vapour.
1 Scope and object
This part of IEC 60068 establishes a test method for determining the ability of components or
equipment to withstand transportation, storage and use under conditions of high humidity.
The object of this document is to investigate the effect of high humidity at constant temperature
without condensation on a specimen over a prescribed specified period.
It is applicable to small equipment or components as well as large equipment, and can be
applied to both heat-dissipating and non-heat-dissipating specimens.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 60068-1:2013, Environmental testing - Part 1: General and guidance
IEC 60068-2-67, Environmental testing - Part 2-67: Tests - Test Cy: Damp heat, steady state,
accelerated test primarily intended for components
IEC 60068-3-6, Environmental testing – Part 3-6: Supporting documentation and guidance –
Confirmation of the performance of temperature and humidity chambers
IEC Guide 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
3 Terms and definitions
None.
For the purposes of this document, the terms and definitions given in IEC 60068-1 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 General test procedure
4.1 General
Test Cab can be applied to both heat-dissipating and non-heat-dissipating specimens.
The temperature and relative humidity limits given in this document are intended to take into
account errors in the measurement, slow changes of temperature, and temperature variations
of the working space.
NOTE 1 For further information on the working space, see IEC 60068-3-6.
The temperature and relative humidity refer to the control sensor of the test chamber, if not
specified other
...