According to NFPA 70, what criteria is used to determine the number and size of conductors in a raceway?

The number and size of conductors in a raceway are determined primarily by the raceway size. This involves considering the physical capacity of the raceway to accommodate a certain number of conductors without overcrowding, which can lead to overheating and potential failure of the electrical system. NFPA 70, also known as the National Electrical Code (NEC), provides detailed specifications regarding the fill capacity of raceways to ensure safety and functionality.

While other factors like voltage rating, conductor type, and ambient temperature may have relevance in specific contexts, the raceway size is fundamentally critical in establishing how many conductors can safely fit inside it without exceeding its mechanical or thermal limits. This is crucial for ensuring both compliance with safety standards and the effective operation of electrical systems.