Shortcircuit explosions sometimes occur in the main terminal box (TB) of highvoltage (HV) motor, resulting in serious personal injuries or losses of property. It is of great practical significance to study the shortcircuit capacity of main TB. Based on the 10 kV pressure relief TB, the shortcircuit capacity test at 40 kA with a duration of 0.25 s is introduced. The universality suggestions of the TB design with high safety level are also proposed based on the test result, so as to reduce the risk of shortcircuit explosion from the design, and ensure safe and reliable operation of the main TB in the industrial field.