Part 2: Residual magnetism method
1 Scope
This document specifies the principle, apparatus, equipment and materials, tested materials, methods and procedures, and criteria of residual magnetism method in the technical determination methods for electrical fire evidence.
This document is applicable to determination of excessive-current short circuit or lightning strike according to the residual magnetism data obtained from the detection of ferromagnetic metal conductors when no melted marks induced by short circuit or lightning strike are found at the building fire scene during fire accident investigation.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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.
GB/T 16840.1 Technical determination methods for electrical fire evidence - Part 1: Macroscopic method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 16840.1 and the following apply.
3.1
residual magnetism
magnetism retained by a ferromagnet after being magnetized by a magnetic field formed by short-circuit wire current or lightning strike current
3.2
melted mark induced by lightning
melted mark formed by metal under the action of lightning current at high temperature
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus, equipment and reagents
5.1 Apparatus
5.2 Equipment
5.3 Reagents
6 Tested materials
6.1 Types
6.2 Selection
7 Methods and procedures
7.1 Preparations
7.2 Measurement operation
8 Criteria
8.1 Data criteria
8.2 Comparison
8.3 Judgment of magnetization law
Part 2: Residual magnetism method
1 Scope
This document specifies the principle, apparatus, equipment and materials, tested materials, methods and procedures, and criteria of residual magnetism method in the technical determination methods for electrical fire evidence.
This document is applicable to determination of excessive-current short circuit or lightning strike according to the residual magnetism data obtained from the detection of ferromagnetic metal conductors when no melted marks induced by short circuit or lightning strike are found at the building fire scene during fire accident investigation.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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.
GB/T 16840.1 Technical determination methods for electrical fire evidence - Part 1: Macroscopic method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 16840.1 and the following apply.
3.1
residual magnetism
magnetism retained by a ferromagnet after being magnetized by a magnetic field formed by short-circuit wire current or lightning strike current
3.2
melted mark induced by lightning
melted mark formed by metal under the action of lightning current at high temperature
Contents of GB/T 16840.2-2021
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus, equipment and reagents
5.1 Apparatus
5.2 Equipment
5.3 Reagents
6 Tested materials
6.1 Types
6.2 Selection
7 Methods and procedures
7.1 Preparations
7.2 Measurement operation
8 Criteria
8.1 Data criteria
8.2 Comparison
8.3 Judgment of magnetization law
