Master Electrician Practice Exam

What is the minimum bend radius for trade size 4 inch rigid metal conduit (RMC) when not using a one-shot or full-shoe bender?

1. 18 inches

2. 20 inches

3. 22 inches

4. 24 inches

The correct answer is: 24 inches

The minimum bend radius for a trade size 4 inch rigid metal conduit (RMC) when not using a one-shot or full-shoe bender is 24 inches. This specification is critical to ensure that the conduit does not suffer any deformation, damage, or impede the installation of conductors. Proper bending techniques and adhering to the minimum bend radius is essential to maintain the integrity of both the conduit and the wiring it houses. The National Electrical Code (NEC) provides guidelines for the bending of conduits to prevent stress on the conduit and to ensure that the conductors can be easily pulled through without risking damage. Bending a conduit too tightly can lead to issues such as wire insulation damage, reduced conduit fill capacity, and long-term reliability concerns. The specified 24-inch minimum bend radius for a 4 inch RMC serves as a standard that supports these best practices in electrical installations.