A tube, rack, shaft, or conduit to get electrical wiring between floors.
Electrical Riser Diagram
An electrical riser diagram (also known as a "one-line" diagram) is a drawing that shows how an electrical system is designed by diagramming how the different components are connected. It is the roadmap which electricians use as the directions to how the system is put together. This can be a simple diagram with only one electrical panel as you would find in a house. Or, it could be it could contain several hundred distribution devices as you would find in a 30-story hotel. Either way, the electrical riser diagram shows the sizes and locations of all transformers, panelboards, conductors, conduit, etc. in am electrical design.