(1) The whole electrical box is small in size, too compact, with high density of components and lack of necessary space. Some electrical boxes put components on both sides, which is not conducive to heat dissipation and easy to be disturbed.

(2) The design layout and component layout of the electrical box are incorrect and unreasonable.

(3) Strong circuit and control circuit are not separated, strong circuit cable box control cable industry is not separated, and some power switches are close to PLC, which is easy to be interfered.

(4) The shielding is not well grounded. Some MPI shielding wires are not well connected or not well connected. Signal connectors and cables are not fixed, which may cause interference and poor contact.

(5) The selection of air conditioning capacity is small and the quantity is small, which can't meet the requirements of heating. For high-power heating elements, such as: high-power driving power without axial-flow fan, etc.