Article 668 pertains to which type of equipment?

Article 668 of the National Electrical Code (NEC) specifically addresses the requirements for electrolytic cells. These electrolytic cells are typically used in industrial processes like electroplating, metal refining, and chemical manufacturing. The provisions in this article ensure safety and proper installation practices for equipment that operates on the principle of electrolysis, which involves driving a chemical reaction through the application of an electric current. This article provides guidelines for aspects such as wiring methods, disconnecting means, and special requirements due to the hazardous nature of the processes involved.

Understanding this helps clarify why the other options do not align with Article 668. For instance, audio signal processing equipment falls under different NEC articles concerning communications and sound systems, while X-ray equipment is covered under articles specific to medical and radiation safety. Sensitive electronic equipment typically refers to devices that may need special consideration for surge protection and power quality, which is addressed under separate guidelines in the NEC. Therefore, knowing that Article 668 is dedicated to electrolytic cells highlights the specificity of NEC articles to different types of electrical equipment and their operational contexts.