What is used to determine the number and size of conductors in a raceway according to NFPA 70?

The number and size of conductors in a raceway are primarily determined by the raceway size, as specified in the National Electrical Code (NEC), which is referenced by NFPA 70. The raceway needs to be adequately sized to accommodate the conductors while allowing for safe installation and maintaining the necessary clearances according to code requirements.

Factors that influence conductor capacity, such as derating factors for temperature and the number of conductors, further rely on the dimensions of the raceway. Therefore, understanding the raceway size is critical for ensuring compliance with electrical safety standards and ensuring that the conductors can operate effectively within the given space without overheating or causing electrical hazards.

While the other options, such as conductor material, voltage rating, and current capacity, play roles in the overall electrical design and safety, they do not directly determine how many conductors can fit within a specific raceway. These factors would influence other aspects of the electrical system but are not the primary determinants for raceway conductor management according to the NEC.