No raceway or compartment of a multiple-channel raceway shall contain conductors that are connected to different power or distribution transformers or other different sources of voltage except where the conductors:
(a) Are separated by the metal armour or metal sheath of cable assemblies of the types listed in Table 19; or
(b) Are separated by a barrier of sheet steel not less that 0.0528 inch (No. 16 MSG) thick or a flame-retardant nonmetallic insulating material not less than 1.5 mm in thickness; or
(c) Are used for the supply and/or control of remote devices, are insulated for at least the same voltage as that of the circuit having the highest voltage, and none of the conductors of the circuits of lower voltages is directly connected to a lighting branch circuit.
Rationale and Intent for Rule 12-904(2).
We intend to prevent conductors of different systems from becoming crossed and impressing another voltage on a circuit. We intend that conductors from different transformers or other sources of voltage not be installed in the same raceway or compartment of a multi-channel raceway, except where the conductors are used for the supply and/or control of remote devices and are insulated for the highest voltage in the enclosure. We intend that the lower voltage conductors not be directly connected to lighting branch circuits. Conductors of different systems may be installed in the same raceway or compartment, provided they are separated by enclosure in an armoured cable or metal-sheathed cable or by a barrier of sheet steel. For example, the conductors of a 115 V control circuit may be installed in the same conduit supplying a 440 V, 3-phase motor, provided all the conductors insulation is rated 600 V.
Electrical Safety Authority