Windmiller,
(E) Grounded Conductors of Multiconductor Cables The insulated grounded conductors in a multiconductor cable shall be identified by a continuous white or gray outer finish or by three continuous white stripes on other than green insulation along its entire length. Multiconductor flat cable 4 AWG or larger shall be permitted to employ an external ridge on the grounded conductor.
Exception No. 1: Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, grounded conductors in multiconductor cables shall be permitted to be permanently identified at their terminations at the time of installation by a distinctive white marking or other equally effective means.
Unless you can meet the requirements of the exception, you cannot re-identify a conductor of a multiconductor cable as a grounded conductor no matter what the size is.
