To facilitate the installation of switch boxes or outlet boxes and easily form a distribution duct for passenger room or crew's room by forming in advance holes for housing switches or outlets in one side (surface section) of a cable duct (hereafter referred to also as 'wiring duct'), preparing several sets of the duct surface sections with switch box or outlet box installation holes formed in specified positions, combining such duct surface sections as required to appropriately position the switches or outlets, and coupling them.

In the case where the title cable duct 1 is to be used for the distribution system for crew's rooms on a ship, it is formed of a duct base 3 to be installed and secured on a side wall of the room, the cross section of which is almost in L shape; and a duct cover 2 to be opposed and anchored to the duct base 3, the cross section of which is almost in L shape. At least a power supply outlet 4, a switch 5, an electric wire pass-through chip 6, and a television antenna outlet are formed on the surface of the duct cover 2.