Device families can be used by any MEP discipline to represent the types of components that are crucial to engineering systems but do not necessarily play a major part in the physical model of the systems. Components such as thermostats, switches, and receptacles are all important to how engineering systems are used, yet their size is generally not an issue when it comes to interferences with other model components.
Although devices do not require very detailed modeling, it is useful to have solid geometry that represents the devices in your projects. This will allow you to coordinate their locations when it is important to collaborate with other disciplines. It may seem unnecessary to model receptacles or switches, ...