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

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

• A. Raceway size
• B. Branch circuit rating
• C. Conductor ampacity
• D. Voltage drop requirements

Answer: (A)

The main idea is that raceway fill, dictated by the raceway’s internal size, determines how many conductors and what sizes can be placed inside it. NFPA 70 uses the raceway’s cross-sectional area and allowable fill percentage to calculate how many conductors of given sizes will fit. If the conductors would exceed the allowable fill, you must use a larger raceway or reduce the number/size of conductors. This is why the raceway size sets the limit on the number and size of conductors. Conductor ampacity or branch circuit rating affect protection and current-carrying capacity, but they don’t establish the physical count and sizing inside the raceway by themselves; voltage drop considerations can influence conductor size but aren’t the primary determinant of how many conductors fit in a raceway.

The main idea is that raceway fill, dictated by the raceway’s internal size, determines how many conductors and what sizes can be placed inside it. NFPA 70 uses the raceway’s cross-sectional area and allowable fill percentage to calculate how many conductors of given sizes will fit. If the conductors would exceed the allowable fill, you must use a larger raceway or reduce the number/size of conductors. This is why the raceway size sets the limit on the number and size of conductors. Conductor ampacity or branch circuit rating affect protection and current-carrying capacity, but they don’t establish the physical count and sizing inside the raceway by themselves; voltage drop considerations can influence conductor size but aren’t the primary determinant of how many conductors fit in a raceway.