a corrugated tube with a longitudinal slit is loaded with electrical wires and the slit is locked . this process is effected using one device and in a single step . the corrugated tube is provided on its outer surface with circular peaks and troughs alternating along the axial direction . the portions facing one another across the slit are provided with convex and concave shapes along the circumference of the tube forming female and male locking portions . the male locking portion is inserted under the female locking portion , so as to lock the slit . an automatic locking device has a tubular guiding unit having a slanted tube part , and a tubular locking unit . the wires pass through the slanted tube part and the tubular locking unit . the tubular guiding unit is inserted into the slit , and the corrugated tube inside the tubular locking unit . when the device and the corrugated tube are moved relative to each other in the longitudinal direction , the wires are transferred from the device into the corrugated tube and the slit is automatically locked .