According to NEC Chapter 9 Table 2, what is the minimum permitted radius for a 2-inch RMC containing THWN conductors when using a single-operation bending machine?

According to NEC Chapter 9 Table 2, what is the minimum permitted radius for a 2-inch RMC containing THWN conductors when using a single-operation bending machine?

• A. 9 1/2 in.
• B. 12 in.
• C. 15 in.
• D. 19 in.

Answer: (A)

Minimum bend radii are specified to prevent damage to insulation and to ensure proper fill and clearance when bending conduit. NEC Table 2 for Chapter 9 sets the smallest allowable bend radius for rigid metal conduit based on the conduit size and the conductors inside, with a distinction for single‑operation bending. For a 2-inch RMC, the outside diameter is about 2.375 inches. In a single‑operation bend with THWN conductors, the table requires a radius of 4 times the conduit’s outside diameter. That gives 2.375 × 4 = 9.5 inches, i.e., 9 1/2 inches. This is the minimum radius allowed. The other options are larger radii and would be acceptable, but they’re not the minimum.

Minimum bend radii are specified to prevent damage to insulation and to ensure proper fill and clearance when bending conduit. NEC Table 2 for Chapter 9 sets the smallest allowable bend radius for rigid metal conduit based on the conduit size and the conductors inside, with a distinction for single‑operation bending.

For a 2-inch RMC, the outside diameter is about 2.375 inches. In a single‑operation bend with THWN conductors, the table requires a radius of 4 times the conduit’s outside diameter. That gives 2.375 × 4 = 9.5 inches, i.e., 9 1/2 inches. This is the minimum radius allowed.

The other options are larger radii and would be acceptable, but they’re not the minimum.