Although the hard-wired electrical box has a long history and is bulky, which goes against the trend of miniaturization and light-weight of contemporary automotive electrical appliances, in entry-level cars, in order to save costs, the passenger compartment electrical box is still widely used.
It is worth mentioning that in the field of commercial vehicles, due to the large number of variants, in addition to the hard-wired electrical box in the passenger compartment, further modular technology is required (Figure 7).
Just like piecing together Lego, this modular approach can be extended many times to create very complex combinations.