Burned Connector? Fire Hazard Inspection At The Cold-pressed Pin Crimping Point.

Many people find that during circuit maintenance, even though they've used qualified wires, the crimping points on the crimp contact male terminals inexplicably start catching fire. This is often not due to poor component quality, but rather to hidden problems in the installation details.

The Truth Behind Abnormal Overheating at Crimping Points

Currents flowing through points with high contact resistance generate intense heat. If the pressure of the crimping tool is not adjusted properly, there will be a tiny gap between the copper core and the terminal inside the crimp socket contact. These gaps, in humid or vibrating environments, will form an oxide layer, causing the resistance to spike. When the load current passes through this obstructed point, the local temperature can quickly exceed the ignition point of the insulation.

If the physical connection is not tight enough, arcing will repeatedly occur in places invisible to the naked eye. This continuous electrical spark directly carbonizes the surrounding plastic casing, ultimately causing sparks to erupt at the crimping point.

Several Operational Details Leading to Fires

Circuit fires are usually caused by these common human errors:

• Inaccurate wire stripping length: The insulation is pressed into the terminal housing, reducing the contact area.

• Incorrect specifications/ratio: Using a large terminal to press a thin wire, even with deep indentations, will still result in internal looseness.

• Severe die wear: Deformed crimping jaws cause uneven force, leading to one-sided contact.

• Improper burr removal: Exposed, loose copper wires on the outer shell pose a short-circuit risk.

Assessing the strength of the physical connection:

The most direct way to determine if the female crimp contact is properly installed is through a pull-out force test. Relying solely on feel is often misleading. Only when the metal shell completely encloses each core wire can it maintain low-temperature operation under high current conditions. The crimped shape should show a neat hexagonal or four-point indentation, without any signs of looseness.