An engineering project is frequently divided into three phases: Schematic Design (SD), Design Development (DD), and Construction Documents (CD). How much gets done by the end of each phase is a matter of client requirements, and varies widely.
In my view, by the end of the DD phase, you have the one-line and riser diagrams nearly complete, all panelboards located, all electric rooms laid out, receptacle outlets placed in offices and corridors, and equipment connections shown for all mechanical and plumbing equipment that appears on their drawings. None of the circuiting is even started at this point.
If there are mechanical or plumbing items that are not yet shown on their drawings, but that you know will eventually be included in their design, then put an equipment connection in some likely location. The reason is that the owner will probably use the 50% and 100% DD package as the basis for getting construction cost estimates. It helps the owner if you do your best to convey a complete scope of work, even if many of the details are yet to be designed.
