Prefabricated electrical modules and system along with fabrication and construction methods are provided. The prefabricated electrical system includes multiple framed, prefabricated electrical modules of one or more types. The prefabricated electrical module disclosed may comprise one or more of a main service electrical module, a low-voltage module, a switch component module, and a receptacle component module. The casing of the interior components of the modules is weatherproofed and/or weatherized. Each of the modules includes a module exterior frame that accommodates the specialized elements of that particular module. Methods for fabrication of the modules are disclosed. Construction methods for installing the assemblies are also disclosed.