This article presents research on the influence of an electric arc on the properties and structure of a traction section guide made of ETP (Electrolytic Tough Pitch) copper in a segment insulator of a railway section. An electrical discharge occurring during use, which may accompany the passage of the pantograph current collector between adjacent guides, may cause many physical phenomena. In addition to existing guide wear mechanisms, such as friction, corrosion, and/or oxidation, the action of an electric arc also has a devastating effect on the guide in use, causing its complete destruction in extreme cases. The aim of the investigation was to determine what type of damage to the sectional guide in real operation conditions was caused by the impact of an electric arc that is induced when the pantograph passes from one guide to the adjacent one. The paper presents the results of tests on an operational guide made of hard electrolytic copper Cu-ETP, in particular the results of microscopic observations, the results of microscopic tests obtained using the ZEISS SUPRA 25 scanning electron microscope, as well as the analysis of the chemical composition in micro-areas (EDS - Energy-dispersive X- ray spectroscopy). On the basis of the tests carried out, it was found that the dominant destructive mechanism of the guide is the electric arc, the presence of elements from the external environment was also determined, and the degree of damage was analysed depending on the conditions and operating times.