KT conduit with companion coupling

Claim 1

A conduit and companion coupling arrangement for rigid electrical conduit comprising a coupling member having internal threads extending continuously therethrough, and a pair of conduit sections in end-to-end abutting relationship each having a threaded end portion, said coupling member being threaded fully onto one of said conduit sections in an uncoupled position and threaded substantially equally onto both of said conduit sections in a coupled position, said threaded end portions on the conduit sections comprising non-tapered threads and said internal threads in said coupling member being non-tapered, at least one of said conduit sections having a nonthreaded area behind the respective threaded end portions, said nonthreaded area being of less diameter than the outside diameter of said conduit sections and substantially the same as the smallest diameter of said threaded end portions, said nonthreaded area of less diameter providing space for receiving said coupling member in the uncoupled position, and an annular shoulder at the inner end of said nonthreaded area where the area of less diameter joins the outside diameter of such conduit section to act as a limit stop to inward movement of the coupling member, the combined lengths of said threaded end portion and said nonthreaded area on one of said conduit sections being substantially equal to the length of said coupling member and said coupling member in the uncoupled position engages said shoulder at one end of the coupling member and the opposite end thereof is disposed substantially flush with the end of said conduit section.