Where can arc-fault requirements for dwelling units be found?

Arc-fault circuit interrupter (AFCI) requirements for dwelling units are specifically outlined in Section 210.12 of the National Electrical Code (NEC). This section addresses the need for AFCIs in residential settings to enhance safety by reducing the risk of electrical fires caused by arc faults.

AFCIs detect and interrupt potentially dangerous arc faults in electrical wiring, which can occur due to various factors such as damaged wiring or loose connections. By ensuring that these types of circuits are properly incorporated into dwelling units, the NEC aims to protect residents from electrical hazards.

The other sections mentioned do not pertain to arc-fault requirements for dwelling units. For example, Section 210.21 covers the general requirements for branch circuits, Section 310.16 is about conductor ampacity and adjustment factors, and Section 220.51 discusses branch-circuit load calculations. Thus, Section 210.12 is the correct reference for the requirements related to arc-fault protection in residential installations.