An important concept to understand before we jump into the next section is MEP connectors. MEP stands for Mechanical, Electrical, and Plumbing in the world of building engineering.

For system engineers, all MEP components require connectors to behave with intelligence. Components created without connectors cannot participate in a system topology. Connectors are primarily logical entities that allow calculating loads within a project. Revit maintains information about loads associated with the spaces in a project. As devices and equipment are placed in spaces, Revit keeps track of the loads based on load type: HVAC, Lighting, Power, Other. The loads associated with the spaces can be viewed in the instance properties for each space and displayed in schedules.

For architects and structural engineers, knowing how to add and remove connectors to loadable families can be useful when using building components, such as manufactured items from Inventor®, or when exporting a building site to civil engineering applications, such as Civil 3D®. For example, you might want to add, move, or delete a connector for a pipe that connects a custom vanity designed in Inventor to a plumbing system in Revit. Or, you might want to modify the connectors on-site utilities, such as gas or water connections, before they are exported with the building site. After the building site is imported into Civil 3D, the connectors on the site utilities become fully functional.

You can learn more about MEP Connectors in Revit documentation. For example here.