Sounds like a violation of 300.3(B):
(B) Conductors of the Same Circuit. All conductors of the
same circuit and, where used, the grounded conductor and all
equipment grounding conductors and bonding conductors shall
be contained within the same raceway, auxiliary gutter, cable
tray, cablebus assembly, trench, cable, or cord, unless otherwise
permitted in accordance with 300.3(B)(1) through (B)(4).
All circuit conductors of an individual circuit must be grouped in
order to reduce inductive heating and to avoid increases in overall
circuit impedance. A similar rule is found in 300.5(I).
(1) Par alleled Installations. Conductors shall be permitted
to be run in parallel in accordance with the provisions of
310.10(H). The requirement to run all circuit conductors within
the same raceway, auxiliary gutter, cable tray, trench, cable, or
cord shall apply separately to each portion of the paralleled
installation, and the equipment grounding conductors shall
comply with the provisions of 250.122. Parallel runs in cable
tray shall comply with the provisions of 392.20(C).
Exception: Conductors installed in nonmetallic raceways run
underground shall be permitted to be arranged as isolated
phase installations. The raceways shall be installed in close
proximity, and the conductors shall comply with the provisions
of 300.20(B).
(2) Grounding and Bonding Conductors. Equipment
grounding conductors shall be permitted to be installed outside
a raceway or cable assembly where in accordance with
the provisions of 250.130(C) for certain existing installations
or in accordance with 250.134(B), Exception No. 2, for dc
circuits. Equipment bonding conductors shall be permitted to
be installed on the outside of raceways in accordance with
250.102(E).
(3) Nonferrous Wiring Methods. Conductors in wiring
methods with a nonmetallic or other nonmagnetic sheath,
where run in different raceways, auxiliary gutters, cable trays,
trenches, cables, or cords, shall comply with the provisions
of 300.20(B). Conductors in single-conductor Type MI cable
with a nonmagnetic sheath shall comply with the provisions of
332.31. Conductors of single-conductor Type MC cable with a
nonmagnetic sheath shall comply with the provisions of 330.31,
330.116, and 300.20(B).
(4) Enclosures. Where an auxiliary gutter runs between a
column-width panelboard and a pull box, and the pull box
includes neutral terminations, the neutral conductors of circuits
supplied from the panelboard shall be permitted to originate
in the pull box.
