General industry electrical standards
Subpart S is the electrical section of the general industry standards, running from 1910.301 through 1910.399. It splits into two halves that get confused constantly: how the installation must be built, and how people must work on it.
The design half
Sections 1910.302 through 1910.308 cover the electrical installation itself: wiring design and protection, wiring methods and components, equipment for general use, and requirements for hazardous locations and special systems. This is the half an electrical inspector reads.
The work practices half
Sections 1910.331 through 1910.335 cover safety-related work practices: who may work on or near energized parts, when work may be performed energized at all, and what protective equipment and precautions apply. This is the half that gets cited after an incident, and it is the half NFPA 70E expands into usable method.
Where training sits
The training requirement lives in the work practices half. It applies to employees who face a risk of electric shock that the installation standards have not reduced to a safe level, and it distinguishes what qualified persons must be trained to do from what unqualified persons need to know. That distinction is the whole game.
What it does not do
Subpart S does not tell you how to calculate an arc flash boundary, select PPE by incident energy, or write an energized work permit. It tells you the outcome required. NFPA 70E is where the method lives, which is why the two are always discussed together.