Patent ID: 7404582

Claim:
A conduit coupling assembly for connecting multiple lengths of conduit for containing electrical cable comprising, in combination: a first length of conduit including an insertion end with an outside diameter defining an outer surface; a second length of conduit including a bell portion with an inner diameter defining an inner surface, the bell portion shaped and configured to receive the insertion end of the first length of conduit, the bell portion including at least a first and second aperture formed therethrough; a rivet fixedly secured in each aperture, the rivet having internal threads for receiving a threaded set screw, each set screw having a head with a bottom contacting surface; whereby the outside surface of the rivet contacts the bottom contacting surface of the head of the set screw to provide frictional engagement between the rivet and the set screw when the set screw is in a tightened position, effective to achieve tightening with ¼ to 1½ turns, wherein each aperture is located on a raised boss so that when the rivets are disposed within the apertures, an inside surface of the rivets sits substantially flush with the inner surface of the bell portion, wherein the apertures are aligned on the bell portion in radial alignment or in longitudinal alignment, wherein the bell portion includes a first and a second end, the first end defined by an end of a receiving end and the second end defined by a transition run, whereby the distance between the first end and the second end is greater than 3 inches, wherein each set screw has a double lead thread or a triple lead thread, wherein each set screw includes a thread profile measuring between 4 and 12 threads per inch and a length measuring less than 0.5625 inches, and wherein the difference between the inner diameter of the bell portion and the outside diameter of the insertion end is less than 0.060 inches to provide an improved mechanical fit between the lengths of conduit when the insertion end is positioned in the bell portion.