NEC Article 518 outlines the requirements for electrical installations in assembly occupancies, which are buildings or spaces designed for the gathering of 100 or more people for purposes such as deliberation, worship, entertainment, eating, drinking, amusement, awaiting transportation, or similar activities. Here is a detailed overview of the key sections and requirements within this article:

518.1 Scope

This section defines the scope of Article 518, covering electrical installations in assembly occupancies. It ensures that these installations meet specific safety standards to prevent hazards in places where large numbers of people congregate.

518.2 General Classification

Specifies the types of buildings and spaces that fall under assembly occupancies. This includes theaters, auditoriums, churches, restaurants, and casinos. The classification helps in determining the applicable requirements for electrical installations based on the type of occupancy.

518.3 Temporary Wiring

Details the requirements for temporary wiring in assembly occupancies, such as those used in exhibition halls for trade shows. Temporary wiring must be installed in accordance with Article 590, and specific provisions are made to ensure safety and prevent hazards.

518.4 Wiring Methods

Specifies the acceptable wiring methods for fixed installations in assembly occupancies. These methods include:

• Metal raceways
• Flexible metal raceways
• Nonmetallic raceways encased in at least 50 mm (2 inches) of concrete
• Type MI, MC, or AC cable

A new section, 518.4(B), was added to address the inclusion of Power over Ethernet (PoE) systems and the use of data cables for powering devices like LED lighting. This section ensures that low-voltage systems are installed safely and meet the necessary standards for assembly occupancies.

518.5 Supply

Outlines the requirements for supplying power to portable switchboards and power distribution equipment used in assembly occupancies. This includes ensuring that these supplies are protected by overcurrent devices and that provisions are made for grounding conductors.

518.6 Illumination

Specifies the requirements for illumination in assembly occupancies to ensure adequate and safe lighting. This includes provisions for emergency lighting systems to be in place and operational during power outages or other emergencies.

These provisions ensure that electrical installations in assembly occupancies are safe, reliable, and meet the necessary standards to protect large gatherings of people.

For more detailed information, refer to the NEC Handbook and additional resources provided by the NFPA. More insights can be found on resources like Electrical License Renewal, IAEI Magazine, and The NEC Wiki.