Three-phase NEMA frame general purpose AC motors don't require starting capacitors, run capacitors, or centrifugal starting switches that can wear out and fail. Motors operate with a higher torque and greater efficiency than single-phase models of the same HP, rpm, and frame size. They have three-windings that create a naturally rotating magnetic field within the frame of the motor and are suitable for use in nonhazardous applications with pumps, ventilation equipment, machine tools, and other industrial equipment. Motors may have a single protrusion on the motor shell such as a conduit box that houses the electrical connections between the external power cables and the internal electrical wiring of the motor. They have NEMA frame construction with standard dimensions that allow drop-in replacement of motors from multiple suppliers with no modifications required to existing installations. The frame size for these motors is shown on the motor nameplate under “Frame” or “FR”.