Abstract: In order to explore the phenomenon of luminous connection caused by poor contact of terminal zero of distribution box and its temperature rise law, an experimental platform was built to simulate the poor contact state, and the temperature rise experiments of terminal-conductor system under different current and torque conditions were carried out systematically, revealing the temperature change characteristics and the macro-morphological evolution mechanism of conductor during luminous connection. By controlling the current and tightening torque to simulate different degrees of poor contact, the temperature rise process and apparent changes were observed and recorded. The results show that the temperature rise after the formation of luminescent connection can be divided into two typical stages, and the macro-change characteristics of the conductor are consistent under different conditions. Poor contact and current significantly affect the degree of heating: poor contact can lead to luminous connection at a small current, while the temperature rises sharply at a large current, which significantly increases the fire risk, and the electrical protection device often fails to act in time under such faults, further increasing the fire risk. This study clarifies the core characteristics and risk mechanism of terminal heating caused by poor contact, which provides experimental and theoretical support for fire warning and safety protection of distribution box system, and is of great value to improve the monitoring and prevention ability of poor contact faults in the design and maintenance of distribution system, and lays the foundation for the subsequent research on luminous connection under multivariable coupling conditions.

Key words: poor contact, luminous connection, macroscopic changes, fire risk