This installation violates Section 300-20(a). Where conductors carrying alternating current are grouped together and installed in metal enclosures or metal raceways, they are required to be arranged so as to avoid heating the surrounding metal by induction. To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors must be grouped together. This is not done here in these ferrous metal raceways.
See Section 300-20(b) FPN: Because aluminum is not a magnetic metal, there will be no heating due to hysteresis; however, induced currents will be present. They will not be of sufficient magnitude to require grouping of conductors or special treatment.
See also Section 310-4, Conductors in Parallel. Aluminum, copper-clad aluminum or copper conductors of size No. 1/0 and larger, comprising each phase, neutral or grounded circuit conductor, are permitted to be connected in parallel (electrically joined at both ends to form a single conductor).
FPN: Differences in inductive reactance and unequal division of current can be minimized by choice of materials, methods of construction and orientation of conductors.
