The first four chapters of the NEC apply to all installations, except as modified by Chapters 5, 6, 7, and 8. Chapter 5 applies to Special Occupancies, and within any occupancy you may find “special equipment.”
Chapter 6 provides the requirements for Special Equipment. It is possible to have “special equipment” within a “special occupancy,” in which case an article or articles from both Chapters 5 and 6 will apply. For example, you could have an electric hoist [Art. 610] in an aircraft hanger [Art. 513]. And if the equipment is part of a system that’s designated a Special Conditions installation, something from Chapter 7 will apply.
So what are the criteria for equipment to be considered “special equipment?” These are really handled on a case-by-case basis. But generally, if installation errors can render the equipment itself especially dangerous, Chapter 6 probably has an Article about that equipment.
As with Chapter 5, these are grouped thematically. However, the following belong to no group: electric welders, audio equipment, pipe organs, x-ray equipment, induction and dielectric equipment, integrated electrical systems, and fire pumps.
- Group 1 [Prefab systems]. Electric signs and outline lighting, manufactured wiring systems, and office furnishings.
- Group 2 [Lifting systems]. Cranes and hoists, elevators (and dumbwaiters, escalators, moving walks, etc.).
- Group 3 [Vehicle support]. EVs and truck bays (if electrified).
- Group 4 [Data support]. IT equipment, modular data centers, sensitive electronic equipment.
- Group 5 [Industrial]. Electrolytic cells, electroplating, industrial machinery.
- Group 6 [Water]. Irrigation machines, pools (and spas, tubs, fountains, etc.), bodies of water.
- Group 7 [Alternative energy]. Solar photovoltaic systems, fuel cells, wind systems.
