Standard Active Last Updated: May 14, 2021
ASTM E1350-18

Standard Guide for Testing Sheathed Thermocouples, Thermocouple Assemblies, and Connecting Wires Prior to, and After Installation or Service

Significance and Use

5.1 These test procedures confirm and document that the thermocouple assembly was not damaged prior to or during the installation process and that the extension wires are properly connected.

5.2 The test procedures should be used when thermocouple assemblies are first installed in their working environment.

5.3 In the event of subsequent thermocouple failure, these procedures will provide benchmark data to verify failure and may help to identify the cause of failure.

5.4 The usefulness and purpose of the applicable tests will be found within each category.

5.5 These tests are not meant to ensure that the thermocouple assembly will measure temperatures accurately. Such assurance is derived from proper thermocouple and instrumentation selection and proper placement in the location at which the temperature is to be measured. For further information, the reader is directed to MNL 12, Manual on the Use of the Thermocouples in Temperature Measurement2 which is an excellent reference document on metal sheathed thermocouple uses.


1.1 This guide covers methods for users to test metal sheathed thermocouple assemblies, including the extension wires just prior to and after installation or some period of service.

1.2 The tests are intended to ensure that the thermocouple assemblies have not been damaged during storage or installation, to ensure that the extension wires have been attached to connectors and terminals with the correct polarity, and to provide benchmark data for later reference when testing to assess possible damage of the thermocouple assembly after operation. Some of these tests may not be appropriate for thermocouples that have been exposed to temperatures higher than the recommended limits for the particular type.

1.3 The tests described herein include methods to measure the following characteristics of installed sheathed thermocouple assemblies and to provide benchmark data for determining if the thermocouple assembly has been subsequently damaged in operation:

1.3.1 Loop Resistance: Thermoelements, Combined extension wires and thermoelements.

1.3.2 Insulation Resistance: Insulation, thermocouple assembly, Insulation, thermocouple assembly and extension wires.

1.3.3 Seebeck Voltage: Thermoelements, Combined extension wires and thermocouple assembly.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Book of Standards Volume: 14.03
Developed by Subcommittee: E20.14
Pages: 7
DOI: 10.1520/E1350-18
ICS Code: 17.200.20