CAD stands for "computer-aided design". Taken literally, that could mean a ton of different things, since engineers use computers for design all the time. However, CAD almost universally refers to using computers to do spatially involved work with software programs like Autodesk AutoCAD or similar. CAD is all but necessary for some engineering disciplines, like civil engineers (think grading plans, hydrology, etc.). For electrical engineers, the necessity of CAD programs isn't so obvious.
My short answer to the title of this article is, "No. Electrical engineers don't need to know how to use CAD." A slightly better answer would be, "Electrical power systems engineers don't need to know how to use CAD at an advanced level."
Electrical engineers in power systems can get by in a career without using CAD, but it will limit them. There are plenty of computer design software options out there with different applications, and nobody can be expected to know them all. That said, understanding the software that is important for your company and your particular projects is essential. For those working in the residential field, CAD programs focused on architectural elements like receptacle placement, service entrances, etc. may be the most important. For those working on the design of an industrial facility, 3D modeling software may be important to route duct banks, aboveground conduit and tray segments and more. At a minimum, if you cannot utilize these programs to move around the model and measure things, your ability to design an electrical system to the highest quality will be impaired (or at least make your teammates do a lot of work for you).
Although electrical engineers may be less constrained by strict dimensional requirements, there are still some pretty important problems that are impacted by spacing. Here are some basic and common examples:
Voltage Drop - If a conductor's length is inaccurately measured (including any slacks), then the voltage drop will also be inaccurate. For circuits over long runs serving loads like motors, this could mean the difference between a design that works and one that doesn't.
Underground Heating - If conductors are installed underground in proximity to one another, there will be mutual heating. This will reduce ampacities below tabulated values for a conductor by itself. If we want to model ampacities accurately using Neher-McGrath software (like ETAP or similar), then we need to know all the relevant dimensions between conductors, conduits, duct banks, external heat sources, and more. All of this is essential for accurate modeling.
Access - This one's an easy one, but essential for a good design. The National Electrical Code (NEC), along with a variety of other standards, requires spacing around equipment to ensure a safe workspace. Non-electrical folk often neglect this issue and place equipment in locations that is not suitable for safety or operations & maintenance.
Beyond a basic knowledge of navigating CAD software, electrical engineers also need to understand what is and is not easily do-able in CAD software. Sometimes, things that seem simple to complete are much harder than one would expect given the program's limitations. Other times, things that sound daunting if they were to be completed manually can be done in a fraction of the time with CAD software. It's never a good look to have wasted all day doing something that you could have completed in 10 minutes, had you just asked for help.
My recommendation is that every engineer learn how to use CAD, even if just for the basics. It never hurts to pick up a new skill, and the workforce is always changing. Shifts in the market for electrical engineers from fossil fuels to renewables has changed the expectations of what electrical engineers do, and software knowledge is part of that. Plenty of free courses exist online, and you may find yourself surprised at just how easy it is to use a program like AutoCAD once you get in and start playing around!
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