Oklahoma Electrical Practice Exam

What is the minimum bending radius for a 4 inch rigid metal conduit enclosing THW wires?

1. 18 inches

2. 24 inches

3. 30 inches

4. 36 inches

The correct answer is: 24 inches

The minimum bending radius for rigid metal conduit is an essential aspect to consider when planning electrical installations to ensure the integrity of the conduit and the wires within it. For a 4-inch rigid metal conduit enclosing THW (Thermoplastic Heat and Water-resistant) wires, the industry standard for the minimum bending radius typically requires it to be at least six times the conduit diameter. Since the diameter of the rigid metal conduit in this case is 4 inches, the calculation for the minimum bending radius would be: 4 inches x 6 = 24 inches. This standard ensures that the bending does not put undue stress on the conduit or the wires, helping to prevent damage and maintain safety. Therefore, the correct answer regarding the minimum bending radius for a 4-inch rigid metal conduit enclosing THW wires is 24 inches.