392.20(D) allows single conductors to be bound together in circuit groups (one conductor/phase), and says these groups can be installed in "other than a single layer".
392.22(B)(1)(d) says "Where any of the single conductor cables are 1/0 through 4/0 AWG, the sum of the diameters of all single conductor cables shall not exceed the cable tray width.”
If I have a reduced size neutral, it falls between 1/0 & 4/0. A strict interpretation of code would appear to require that if I reduce my neutral size I must widen the cable tray due to 392.22(B)(1)(d). If all conductors are above 250MCM, I can use table 392.22(B)(1) which results in reduced width.
392.22(B)(1)(d) says "Where any of the single conductor cables are 1/0 through 4/0 AWG, the sum of the diameters of all single conductor cables shall not exceed the cable tray width.”
If I have a reduced size neutral, it falls between 1/0 & 4/0. A strict interpretation of code would appear to require that if I reduce my neutral size I must widen the cable tray due to 392.22(B)(1)(d). If all conductors are above 250MCM, I can use table 392.22(B)(1) which results in reduced width.