Which table would you reference for the ampacity of insulated conductors with not more than three current-carrying conductors in a raceway or earth?

Which table would you reference for the ampacity of insulated conductors with not more than three current-carrying conductors in a raceway or earth?

• A. Table 310.16
• B. Table 240.4(B)
• C. Table 310.15(B)(1)(1)
• D. Table 310.15(C)(1)

Answer: (A)

When there are three or fewer current-carrying conductors in a raceway or in the earth, you don’t derate the ampacity. The correct reference is the main ampacity table for insulated conductors, Table 310.16. This table shows the allowable ampacities for conductors of various sizes based on the insulation’s temperature rating (60°C, 75°C, or 90°C). You simply pick the conductor size and use the column corresponding to your insulation’s rating to determine the ampacity. The other tables are used for derating scenarios or other special conditions, which don’t apply when you have three or fewer current-carrying conductors.

When there are three or fewer current-carrying conductors in a raceway or in the earth, you don’t derate the ampacity. The correct reference is the main ampacity table for insulated conductors, Table 310.16. This table shows the allowable ampacities for conductors of various sizes based on the insulation’s temperature rating (60°C, 75°C, or 90°C). You simply pick the conductor size and use the column corresponding to your insulation’s rating to determine the ampacity. The other tables are used for derating scenarios or other special conditions, which don’t apply when you have three or fewer current-carrying conductors.