Abstract: An insulated electrically conducted shaft for medical coagulation instruments, and particularly for unipolar coagulation instruments is constructed with an insulating jacket consisting of separate conduit pieces formed of insulating material which are slipped onto the shaft. The conduit pieces have abutting end faces which engage adjacent pieces in an overlapping fashion with the overlapping being caused by engagement of two layers of staggered conduit pieces of equal length or by complementary step formed end faces of adjacent conduit pieces or by inner diameter or outer diameter radial dimensioned steppings of the abutting conduit pieces with the resultant gaps filled by filler conduit pieces.