What are the test voltages for contact discharge and air discharge at the edge of the box?

According to IEC 61000-4-2 Industrial Class 4, the contact discharge test voltage for edge computing boxes is ±8kV, and the air discharge test voltage is ±15kV. These are the core indicators for determining the product's anti-static interference capability. Contact discharge is for accessible metal parts such as housings, screws, interfaces, and terminals. Air discharge is for non-conductive surfaces such as gaps, buttons, and indicator lights. Common communication interfaces for edge boxes include RS485 and CAN. It is recommended to use the EENTElectronic ESDLC5V0D8B. This device is named ESD electrostatic protection, LC low capacitance, 5V0 indicates a shutdown voltage of 5.0V, and D8 indicates an SOD882 package DFN1006-2L. The typical junction capacitance is 5pF, which can withstand ±30kV contact discharge, far exceeding the 8kV level. The power port can also use the SMBJ28CA bidirectional TVS, named SMBJ, packaged 600W 28V, belonging to the standard B category. The nominal breakdown voltage is 28V, and the actual VRWM = 28V. The junction capacitance is approximately 200pF, which can absorb 15kV air discharge energy. Actual testing showed that after placing the above devices in the edge box, there were no resets, crashes, or communication interruptions during ESD testing.