2014 Prevention through Design Student Education Engineering Initiative

The common electrical equipment as laptops, printers, refrigerators, table lights, televisions, etc., are supplied by electrical power cables, flexible cords and extension cords, generally of low cross section, constituted by stranded bare conductors. Flexible cords and extension cords are exposed to mechanical damages and other insulation stresses and so can be involved in overheating, arcing and burning. Mechanical damages of the stranded bare conductors can degrade locally the effective sizing of the cross section and cause anomalous local conditions and/or electric shock hazard. The circuit protective devices can be unfit to detect the faults of cords that remain so energized and available to electric shock and fire hazards. A series of simulating tests have confirmed how some fire ignitions of nearby flammable materials result caused from these types of faults. It appears necessary wiring the cords and extension cords with a grounding protection conductor also supplying Class II equipment. In fact involving the ground in every faults allows in AC systems a fast protection by residual current protective devices (RCDs or GFPDs). At this aim the use of special cables, Ground-Fault-Forced Cables (GFFCs), is recommended, particularly for cords and extension cords.