Most projects are only electrical in nature for existing system upgrades so don't really have mechanical or arcitecetual elements. There is a small bit of civil work as necessary to support new equipment.
Most drawings are only 2D drawings, consisting of One-Lines, Site Plans, Floor Plans, Elevations, Schedules, etc....
Drafting work can vary. Time normally spent drafting will instead be time spent managing the drafting team, because they are not designers and have little cues as to what is being communicated on the drawings. As the purchaser of drafting services, consider defining a strict work flow, a folder/file structure that must be adhered to and CAD standards (layers, plot styles, line types, leaders, text height, etc) so that documents appear legible and professional. Legible drawings get less questions. Questions cost money to answer.
For example:
1. The engineering team will furnish requirements, border file, base files, sheet list, and sketches for each drawing.
2. The drafting team will take a first swing and provide a check set upon creating all layouts.
3. The engineering team will review and redline drawings and furnish to drafting team within X business days.
4. The drafting team will incorporate the comments
exactly. Remember they are not designers.
I only point this out to show that while outsourcing CAD might be considered a way to cut costs, there will be coordination time spent by the engineer that offsets the savings. Might not be a big deal for smaller projects like HVAC or drive replacements, but this task should not be underestimated. The nice thing is once a working relationship is established, the work flow will become natural.
We have found the best result is when designers do the grunt work for the CAD and engineers finish it up. Whenever there is a strictly drafting firm involved in the bigger projects, there seem to be construct-ability issues that have a habit of appearing despite an engineer's best efforts to play dream catcher. I find many of these types of issues in the process of drafting because I am spending time thinking about (physically) what I am communicating to the contractor.
