# Effects of Overload Current on the Ignition and Burning Hazards of Polyethylene-Insulated Wires

## TL;DR

This study examines how overload currents affect the ignition and burning hazards of polyethylene-insulated wires, revealing key thresholds and behaviors.

## Contribution

The study provides a quantitative analysis of fire hazards in overloaded wires using synchronized imaging and a novel multi-indicator evaluation framework.

## Key findings

- Stable ignition and sustained burning occur at overload currents ≥180 A.
- Burning duration increases initially with current but stabilizes later due to wire melting.
- Maximum fire hazard occurs at 200 A based on flame height and width measurements.

## Abstract

To quantitatively elucidate the effects of overload current on the ignition and burning hazards of polyethylene-insulated wires, 2.5 mm2 polyethylene-insulated copper wires used commercially were tested in an electrical fire fault simulation system. Experiments were conducted to study the evolution of overloads, ignition, and burning. The entire process, from insulation smoking and ignition to sustained burning and final extinction driven by wire fusing, was recorded using synchronized digital and high-speed imaging. Video-based measurements were used to extract the following: smoking emission duration, ignition time, burning duration, maximum flame height, and segmented flame width. The results show that stable ignition and sustained burning occur when the overload current is greater than or equal to 180 A. As the current increases, ignition occurs earlier, while the smoking stage becomes shorter but exhibits nonmonotonic fluctuations. The burning duration shows a staged response. It first increases, then decreases toward a relatively stable level. This reflects the competition between enhanced Joule heating and accelerated wire melting and fusing. Maximum flame height and segmented flame width vary nonmonotonically with current, and the segmented flame width peaks at 200 A. A multi-indicator fire hazard evaluation framework was established and an entropy-weight TOPSIS method was applied to integrate the quantification and ranking. The overall fire hazard is greatest at 200 A. These findings provide experimental insight into overload-induced ignition and combustion behavior and contribute to a quantitative understanding of fire hazard evolution in overloaded electrical wires.