One: Cause of Charcoal Formation:

If the terminal is blackened, it's not necessarily a sign of burning; oxidation can also cause blackening. How do we verify if it's due to burning? Our method is to wipe it with a finger; if it comes off like ash, it's likely oxidized black material and can only be removed with sandpaper or a file.

Be sure not to wipe with your fingers when it's live! Another possibility is that it's burned black, and aside from fires and qigong masters channeling their energy, there's only one cause: the terminal getting too hot.

Issue Leading to High Temperatures:

There are two possibilities: either the terminals are loose, causing excessive contact resistance and subsequent overheating; or the terminals are not loose, but the circuit is overheating due to an unknown reason, such as overvoltage in the power supply or a short circuit in the load.

1. Voltage Overload. Traceable from the source, including transformer secondary voltage, distribution box voltage, and voltage of each electrical equipment. Power outlets can also feature assembly clips and locking clips. Assembly clips provide a more stable fix to the PCB board, while locking clips secure the housing and outlet after installation. Various outlet designs can accommodate different insertion methods for the housing, such as horizontal, vertical, or angled towards the printed circuit board. Both metric wire gauges and standard wire gauges can be chosen.

2. Ground Fault. It can also be traced back from the transformer to the distribution box grounding. The grounding points should be grounded, while the normal phase lines should be excluded from the grounding fault. An insulation or megger can be used to measure when the power can be temporarily shut off, conducting segment-by-segment measurements. Preferably, only segment the power supply lines such as cables, wires, circuit breakers, switches, etc. In cases where segmentation is extremely difficult, remove the fuses of low-voltage equipment and sensor devices.

The key to grounding lies in low ground resistance and a large contact area. The former ensures that the grounding point has an as low as possible "zero potential" close to the earth's potential, which can prevent the possibility of lightning from "backtracking" through the grounding wire after a thunderstorm and entering the power supply circuit. The latter guarantees sufficient capacity to provide a fault current path, including lightning or short-circuit faults, etc. Since the actual construction techniques are theoretically always changing with contemporary technology and science, whether this grounding method is effective or not depends on the specifications of the new standards.