Series Faults in Electrical Cords and Extension Cords

Abstract

In electrical power systems, the cords and extension cords are exposed to mechanical damage and other insulation stresses. Mechanical damage to the stranded conductors can reduce locally their cross section or break them and cause anomalous local conditions of overheating or arcing. The ordinary protective devices cannot detect the series faults that persist; so the fault point remains energized and subject to electric shock and fire hazards. Effective protection can be accomplished by implementing active and passive measures: installing Arc-fault Circuit Interrupters (AFCI) or Detection Devices (AFDD), able to detect arcing faults; or wiring the circuits with a grounding protection conductor to involve the ground in every fault. In this way, residual current protective devices (RCDs or GFPDs) protect quickly the series faults with arc, but also without arc. The Ground-Fault-Forced Cables (GFFCs) facilitate the conversion of any kind of fault to a ground fault in all the applications and are particularly recommended for cords and extension cords, internal circuits to grounded equipment, UPS continuity circuits, aircraft circuits, road tunnels, data centers, residential houses and hospitals.