I found this section of metal wireway in the attic of a tall building during an electrical inspection. The wireway was not only missing its covers, but at some point in time someone had used this area as a trash receptacle. This would no doubt add fuel load in this space if a fire were to break out in this area. In addition, the blocks used to support the conductors are not a recognized method of installation.
The rules for this type of raceway installation can be found in Art. 376. Section 376.2 defines metal wireways as "sheet metal troughs with hinged or removable covers for housing and protecting electrical wires and cable." The conductors in this type of wireway are laid in place after the complete wireway system has been installed.