Short-circuit Faults on Electrical Wires Exposed to External Radiant Heat

Abstract

Short-circuit faults on electrical cords exposed to external radiant heat are usually initiated by an arcing through charred insulating material or a physical (metal-to-metal) contact of hot conductors. In this study, various types of PVC and rubber-insulated power cords were exposed to external radiant heat by using a cone heater and initial electrical activities on the cords were investigated. Types of short-circuits depended upon the size and types of cords, materials of insulation, strength of external radiant heat, and duration of exposure to the heat flux. Physical shorts occurred on PVC-insulated cords at 20 kW/m² when their conductors were twisted or pinched. PVC-insulated cords required 40 kW/m² to start arcing shorts. Arcing shorts occurred on rubber-insulated cords at 20 kW/m², though physical shorts did not occur at 40 kW/m². The authors discussed on when and how short-circuit faults are produced on electrical cords under exposure to external radiant heat.