A separate structure (commercial trailer) with wheels removed being used as an office and storage is being supplied with 120/208 volts and is feeding a panelboard inside the trailer. The temporary feeder is a non-metallic cable assembly not known if hard usage and the supply power is being supplied from a panelboard inside a permanent building. The temporary cable feeding this structure has been in place for 3-5 years. The cable feed originates from a permanent building and is lying on mechanical room floor and passes through a metal louver vent outside to the separate structure. Outside the cable is run lying on the asphalt. The cable is exposed to employees/pedestrians and a portion of the cable is exposed to vehicle traffic and physical damage. The cable run is on the floor/pavement with no supports or protection.

I am being told this is a compliant temporary installation after looking at article NEC 590 and 1910.304 & 1910.305. The feeder is lying on the ground because 1910.305(a)(2)(v)(C) States: No branch-circuit conductor may be laid on the floor.

Why does OSHA say it is not permissible to have a branch circuit on the floor, but does not mention this about feeders?