In 527.4, the NEC provides specific rules for each major area of application. This is really the meat of the Article. What?s especially useful about this arrangement of the NEC is you can refer to exactly what you are working on. For example, if you are providing a temporary branch circuit, you can refer to 527.4(C) and see what the requirements are. The NEC addresses these areas of application in a logical order, beginning with the service entrance:
Services. You must install a service per Article 230. No slack, here. You must treat a service as permanent, even if it?s temporary.
Feeders. You cannot use open conductors for temporary feeder installations. However, you can use cable assemblies, hard-usage cords, extra-hard usage cords, and NM cable. Exception: You can use individual open conductors for feeders where the individual open conductors are accessible only to qualified personnel.
Branch Circuits. You cannot use open branch-circuit conductors (such as ?festoon lighting?) for temporary installations However, you can use cable assemblies, hard-usage cords, extra-hard usage cords, and NM cables (see Figure 2 un527-02 527-04C.cdr). Exception: You can use open wiring for branch circuits in holiday decorative lighting under certain conditions: the circuit voltage-to-ground does not exceed 150V, the conductors are not subjected to physical damage, and the conductors are supported on insulators at not more than 10 ft intervals
