Which article addresses the safety standards for audio signal processing and amplification?

Article 640 specifically addresses the safety standards for audio signal processing and amplification. This article provides regulations and guidelines that ensure the safe installation and operation of audio equipment, which includes aspects related to signal processing and amplification systems. The focus is on preventing hazards such as electrical shock, fire, and equipment damage, ensuring that technicians and those involved with audio systems can work safely and comply with industry standards.

Other articles mentioned focus on different areas of electrical installations. For example, Article 605 pertains to conductors and wiring methods for low voltage power-limited circuits, while Article 610 deals with elevators and escalators, and Article 625 focuses on electric vehicle charging systems. Each article has a specific scope and set of requirements relevant to its subject area, distinguishing them from Article 640's focus on audio signal processing and amplification.