Article 525 of the National Electrical Code (NEC) provides the requirements for the portable wiring and equipment (and wiring in or on all structures) installed for carnivals, circuses, fairs, and similar events.
Chapters 1 through 4 apply, except as modified by Art. 525. Where there’s a difference, Art. 525 applies to the portable equipment [Sec. 525.3(A)]. Articles 518 and 520 apply to permanent structures at these venues [Sec. 525.3(B)].
Portable structures must be at least 15 ft in any direction from overhead conductors operating at 600V or less [Sec. 525.5(B)]. Obviously, the conductors supplying the structure don’t have to meet this requirement.
Service equipment can’t be accessible to unqualified persons, and it must be securely fastened to a solid backing [Sec. 525.10].
These venues tend to make extensive use of flexible cords and cables; make sure those are listed for extra-hard usage [Sec. 525.20(A)]. Arrange those cords and cables in a way that does not produce a tripping hazard [Sec. 525.20(G)]. Cord covers help satisfy this requirement while also protecting the cords.
Ground fault protection is required for 125V, 15A and 20A non-locking receptacles and branch circuits supplying equipment, where publicly accessible.