General idea of ​​electrical panels: 

An electrical enclosure is a cabinet for electrical or electronic equipment to mount switches, knobs, and displays, to prevent electric shock to equipment users, and to protect the contents from the environment.

The case is the only part of the device that users see.

It may be designed not only for its utilitarian requirements, but also to please the eye.

Regulations may dictate the features and performance of electrical equipment enclosures in hazardous areas, such as petrochemical plants or coal mines. 

Electronic enclosures may impose many requirements on the board for heat dissipation, radio frequency interference, and electrostatic discharge protection, as well as functional, aesthetic, and commercial limitations.