Which article focuses on the use and safety of storage batteries?

Article 480 of the National Electrical Code (NEC) specifically addresses the use and safety of storage batteries. This article outlines the requirements for the installation and maintenance of storage batteries to ensure safe operation. It includes provisions for the storage and charging of batteries, labeling, ventilation, and the prevention of hazardous conditions such as electrical hazards or gas emissions. By focusing on these safety measures, Article 480 helps to minimize the risks associated with battery storage systems, including fire and chemical hazards.

The other articles mentioned do not focus on storage batteries. Article 470 deals with the requirements for the use of power supplies, while Article 490 is concerned with transformers and transformer vaults. Article 500 addresses hazardous (classified) locations, which include environments where explosive or flammable materials are present, rather than specifically the safety and use of storage batteries. Therefore, Article 480 is the correct choice as it specifically targets the relevant safety measures and requirements associated with storage batteries.