Abstract: As one of the most frequently used components in household power distribution systems, socket plugs are highly susceptible to thermal failure caused by overcurrent and poor contact faults, which are major contributors to residential electrical fires. In this study, household single-phase socket plugs with rated currents of 10 A and 16 A were selected. An experimental circuit was constructed using 2.5 mm² BV single-core copper wires and 1.5 mm² BRV multi-core copper wires to simulate two typical fault scenarios: overcurrent and poor contact. Infrared thermography and a fault simulation platform were employed to systematically investigate the temperature rise characteristics and thermal failure behavior under different fault conditions.Results show that when the current exceeds four times the rated value, accompanied by melting, carbonization, and breakage of conductors and insulation, the fire risk is significantly increased. When the contact resistance increases to 100 Ω, even under moderate current, the temperature can exceed 180 °C. If current and resistance rise simultaneously, the peak temperature may surpass 350 °C, forming a thermal runaway positive feedback mechanism. Repeated overload tests also indicate that cumulative thermal fatigue intensifies with the number of cycles, accelerating the occurrence of thermal damage and ignition.This study clarifies the critical temperature thresholds and fire-triggering mechanisms of socket plugs under typical electrical fault conditions, providing important theoretical and experimental references for the structural design, safety evaluation, and fire warning of household electrical accessories.

Key words: socket and plug, overcurrent, poor contact, temperature rise characteristics, thermal runaway