Another item in the IEC specification model is the allowable current, which is 80% of the maximum current. In contrast to this, the UL specification will make the electrical conductor temperature of metal materials higher than 90% of the current when the operating temperature is higher than 30 ℃ as the current tolerance value of the components. It is not difficult to see that the temperature of a part of the electrical conductor of metal materials is a very critical factor in all applications. This is critical for machinery. Because mechanical equipment generally must be in a working environment where the temperature reaches 80 °C. If the temperature of the terminal is 30°C or 45°C higher than this temperature, the temperature of the terminal may exceed 100°C.

Depending on the type of tolerance value and insulation material used for the selected components, products must be operated at a current less than the rated current, so as to ensure that they can work reliably within the expected temperature range. Sometimes, the raw materials suitable for compact package components will not be able to take into account the heat pipe heat dissipation requirements very well, so the current flow of this type of terminal block components must be much less than the rated current. In this way, it can best reflect the necessity of how to choose terminals.