When only three current-carrying conductors are installed within a raceway, which NEC reference controls their allowable ampacities?

The reference that controls the allowable ampacities when only three current-carrying conductors are installed within a raceway is 310.16. This section of the National Electrical Code (NEC) specifies the ampacity of conductors, determining how much current they can carry without exceeding their temperature ratings.

Section 310.16 provides tables that detail the ampacity ratings based on different factors, such as the size and type of conductor, the number of conductors in a raceway, and the ambient temperature. In situations where three current-carrying conductors are present, it is necessary to refer to this section to ensure that the correct ampacity is applied.

It's essential to use this reference because it is specifically designed to address the considerations for conductor ampacity in various configurations, ensuring safe and effective electrical installations. Other sections may provide guidance on different aspects of wiring and conductor considerations but do not specifically address the ampacity calculations needed for three conductors within a raceway like 310.16 does.