Abstract: Interchangeable modular systems for home networking are provided. The systems may contain home energy and appliance monitors controls, and/or home security/surveillance systems. In particular, the systems may use existing electrical gang or junction boxes to house said systems, which may have a high degree of interchangeability or modularity. These systems have useful features in, e.g., the residential home environment and office or industrial buildings. More specifically, modular home automation devices comprising a gang-box microcomputer having a main processor, a communications module, and at least one functional module are provided. Also provided herein are devices for home automation and control comprising a gang-box microcomputer having a form factor fitting inside an existing electrical junction box.