Which article would provide guidelines for the installation of boxes used in electrical systems?

The correct choice is based on the specific provisions that Article 312 of the National Electrical Code (NEC) addresses. Article 312 is dedicated to the installation requirements for boxes, enclosures, and fittings used in electrical systems. It outlines the types of boxes that can be utilized, their sizing, mounting methods, and the conditions under which they must be installed. This ensures safety and functionality in electrical installations, which is critical for both compliance with the code and the prevention of electrical hazards.

Article 280 focuses on overhead conductors and their installations, which does not directly pertain to the installation of boxes. Article 300 provides general requirements for wiring methods and materials, but it does not specifically detail the installation criteria for boxes. Article 310 outlines conductors for general wiring but likewise does not cover the specifics of box installation. Thus, Article 312 is singularly relevant to the guidelines for installing boxes used in electrical systems.