Which of the following articles pertains to circuits operating at less than 50 volts?

Article 720 of the National Electrical Code (NEC) specifically addresses "Circuits and Equipment Operating at Less Than 50 Volts." This article encompasses a range of low-voltage systems, including those used for signaling and communications, ensuring safety and proper installation guidelines for these types of circuits.

The focus of Article 720 is to provide standards for the installation of low-voltage equipment, which can include applications like fire alarm systems, notification appliances, and other signaling systems that operate safely and effectively at low voltage levels. The requirements in this article are tailored to recognize the unique characteristics and safety considerations associated with circuits that operate below 50 volts, such as reduced shock hazards and simplified installation requirements.

Other articles mentioned pertain to different topics: Article 701 deals with essential electrical systems for healthcare facilities, Article 750 covers the installation and operation of power-limited circuits, and Article 800 addresses communications circuits. These do not focus specifically on the low voltage range below 50 volts as Article 720 does.