Which statement correctly describes NFPA 70's raceway sizing?

Which statement correctly describes NFPA 70's raceway sizing?

• A. It defines the color coding of conductor insulation
• B. It determines the number and size of conductors used in a raceway
• C. It prescribes the type of smoke detectors to install
• D. It specifies the maximum length of branch circuits

Answer: (B)

Raceway sizing in NFPA 70 is about how many conductors and what sizes can be placed inside a raceway. The code uses the internal cross-sectional area of the raceway and the cross-sectional areas of the conductors (plus allowances for grounding conductors and space for bending and pulling) to ensure the fill doesn’t exceed what the raceway can safely handle. This protects against overheating and makes installation feasible. That’s why this statement is the best: it captures the purpose of raceway sizing—to determine the number and size of conductors that can be installed in a given raceway. Other options address things like color coding, detector types, or circuit length limits, which are governed by different parts of the code or design considerations, not raceway capacity.

Raceway sizing in NFPA 70 is about how many conductors and what sizes can be placed inside a raceway. The code uses the internal cross-sectional area of the raceway and the cross-sectional areas of the conductors (plus allowances for grounding conductors and space for bending and pulling) to ensure the fill doesn’t exceed what the raceway can safely handle. This protects against overheating and makes installation feasible.

That’s why this statement is the best: it captures the purpose of raceway sizing—to determine the number and size of conductors that can be installed in a given raceway. Other options address things like color coding, detector types, or circuit length limits, which are governed by different parts of the code or design considerations, not raceway capacity.