What is the minimum radius of a field bend on trade size 1 1/4 RMC?

The minimum radius of a field bend for rigid metal conduit (RMC) is typically governed by the National Electrical Code (NEC), which specifies that bends in conduit should not be so tight as to compromise the integrity of the conduit or the wires inside it. For trade size 1 1/4 inch RMC, the NEC dictates a minimum bending radius to ensure proper bending without harming the conduit or the electrical conductors.

In this case, the minimum bending radius for trade size 1 1/4 RMC is 8 inches. This size ensures that the conduit maintains its structural integrity while also providing sufficient protection and space within the conduit for the electrical conductors to be installed without risk of damage.

The other options of 4 inches, 6 inches, and 10 inches do not comply with the NEC standards for bending radius for this size of conduit. Specifically, the radius must accommodate the physical properties of the conduit material and the conductors it will contain, ensuring that no undue stress is placed on either. An 8-inch bend effectively meets these criteria, making it the appropriate choice.