Direct Answer • Key Takeaway
The Id and Od This Is a Fixed Number That Can Not Be Deviated From. for Instance, a 1-Inch Rigid Conduit Will Have an Id of 1.063 Inch Nominal While a 1 Inch Intermediate Metallic Conduit Will Have an Id of 1.12 Inch Nominal, Yet Both Have the Same Knockout Size of 1.375 Inches.