Common Causes

Current flowing through conductors and contact points generates heat. Abnormal temperature rise may result from excessive load current, high contact resistance, mismatched wire sizes, loose connections, or poor heat dissipation. The actual operating conditions and terminal ratings should be considered when identifying the cause.

Key Checks

First, check whether the operating current is within the rated limits of the terminal block and wires. Inspect the wire strip length, insertion depth, and clamping condition. For screw-type terminals, ensure the tightening torque meets product requirements. The use of wire ferrules for stranded wires should follow the product specifications.​

The operating environment should also be considered. High ambient temperatures, heat from nearby components, poor ventilation, and vibration may affect temperature rise. All inspections and maintenance must be performed after safe power isolation and in accordance with electrical safety procedures. Never tighten connections while energized. 

Testing and Selection

If terminals show discoloration, insulation damage, or persistent abnormal heating, stop the affected equipment or circuit. After safely isolating the power supply, qualified personnel should inspect the connection. Temperature rise and contact resistance tests can help identify the cause.​

When selecting terminals, check the rated current, rated voltage, compatible wire cross-sectional area, contact structure, materials, and applicable standards to ensure suitability for the application.

In practical applications, terminal selection should consider equipment conditions, application requirements, and product specifications. ULO GROUP continues to focus on industrial connectivity and control, providing a range of solutions for industrial automation.