Citation

Erlandsson R, Strand G. Fire Safety J. 1985; 8(2): 97-103.

Copyright

(Copyright © 1985, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Scanning electron microscopy, X-ray analysis and optical microscopy have been used in conjunction with metallographic sample preparation in order to study the damage occurring on copper conductors at electrical fire initiation. Both bare wiring and PVC-insulated wiring were studied. The aim has been to distinguish between primary and secondary damages. Three different types of events that can cause fire have been treated separately, namely, sparking (i.e., a short circuit that immediately blows the fuse), electric arcs and resistive heating (overload).These are the main results: 1. (a) Marks from a direct short circuit between bare copper conductors that takes place in smoke from burning PVC are often covered by characteristic, chlorine-rich particles that are easily identified by scanning electron microscopy. In the case of short circuits between PVC-insulated copper conductors, these particles can occur without exposure to fire.2. (b) The pore structure and oxide penetration in a cross section of a bead formed by local melting of the conductor can indicate if damage is primary or not.3. (c) The damage on copper conductors that serve as electrodes in a d.c. arc become characteristic if the arc takes place in an oxygen deficient atmosphere as in a burning fire.