IEC/IEEE 60079-30-2:2025

IEC/IEEE 60079-30-2 ®
Edition 2.0 2025-09
INTERNATIONAL
STANDARD
REDLINE VERSION
Explosive atmospheres -
Part 30-2: Electrical resistance trace heating - Guidance on application for
design, installation and maintenance
ICS 29.260.20  ISBN 978-2-8327-0728-9

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CONTENTS
FOREWORD . 5
1 Scope . 1
2 Normative references . 8
3 Terms and definitions . 8
4 Application considerations . 9
4.1 General . 9
4.2 Corrosive areas . 9
4.3 Process temperature accuracy . 9
4.3.1 Type I . 9
4.3.2 Type II . 10
4.3.3 Type III . 10
4.4 Installation considerations. 10
5 Thermal insulation . 10
5.1 General . 10
5.2 Selection of insulating material . 11
5.3 Selection of weather barrier (cladding) . 12
5.4 Selection of economical thickness to provide optimum trace heating design . 12
5.5 Double insulation . 12
6 System design . 15
6.1 General . 15
6.2 Purpose of, and major requirement for, trace heating . 15
6.3 Training . 16
6.4 Selection of trace heater . 16
6.4.1 General . 16
6.4.2 Site-fabricated trace heaters . 16
6.4.3 Specific types of trace heating . 17
6.5 Maximum temperature determination . 17
6.5.1 General . 17
6.5.2 PTC characteristic . 18
6.5.3 Stabilized design . 18
6.5.4 Controlled design . 18
6.6 Heat up and cool down considerations . 19
6.7 Design information . 19
6.7.1 Design information documentation . 19
6.7.2 Isometric or trace heater configuration line lists and load charts . 20
6.8 Power system . 20
6.9 Earthing requirements . 21
6.10 Earth fault protection of equipment . 21
6.11 Start-up at minimum ambient temperatures . 21
6.12 Long trace heater runs . 21
6.13 Flow pattern analysis . 22
6.14 Dead-leg control technique . 24
6.15 Chimney effect . 24
6.16 Safety shower and eyewash station design requirements . 25
7 Control and monitoring . 25
7.1 General . 25
7.2 Mechanical controllers . 26
7.3 Electronic controllers . 26
7.4 Application suitability . 26
7.5 Location of controllers . 26
7.6 Location of sensors . 27
7.7 Alarm considerations . 27
7.7.1 General . 27
7.7.2 Trace heating circuit alarm . 27
7.7.3 Temperature alarms . 28
7.7.4 Other alarms. 28
7.7.5 Integrated control . 28
8 Recommendations for installation . 28
8.1 General . 28
8.2 Preparatory work . 29
8.2.1 General . 29
8.2.2 Scheduling and coordination . 29
8.2.3 Confirmation of equipment . 29
8.2.4 Receiving materials . 29
8.2.5 Warehousing and handling . 29
8.2.6 Personnel aspects . 29
8.3 Installation of trace heating circuits . 29
8.3.1 Coordination and equipment verification . 29
8.3.2 Pre-installation testing and design verification . 30
8.3.3 Visual examination . 30
8.3.4 Insulation resistance test . 30
8.3.5 Component substitution . 30
8.3.6 Location of power supply . 31
8.3.7 Installation of trace heaters . 33
8.3.8 Connections and terminations . 34
8.4 Installation of control and monitoring equipment . 36
8.4.1 General . 36
8.4.2 Verification of equipment suitability . 36
8.4.3 Temperature controller and monitoring devices . 36
8.4.4 Sensor considerations . 36
8.4.5 Controller operation, calibration, and access . 40
8.4.6 Necessary modifications . 40
8.5 Installation of thermal insulation system (see also Clause 5) . 40
8.5.1 General . 40
8.5.2 Preparatory work . 41
8.5.3 Installation of the thermal insulation materials . 41
8.5.4 Cladding . 41
8.5.5 Field (site work) circuit insulation resistance test . 42
8.5.6 Visual inspection . 42
8.5.7 Documentation . 42
8.6 Installation of distribution wiring and coordination with branch circuits . 42
8.6.1 General . 42
8.6.2 Earth fault protective device . 42
8.6.3 Circuit protective device . 43
8.6.4 Tagging/Identification . 43
8.7 Commissioning .
...