Can I use a red wire as a neutral?
For anyone wanting the code reference as to why using a red (or black) conductor as a neutral is not allowed:


  2014 National Electric Code
  
  200.6 Means of Identifying Grounded Conductors. 
  
  (A) Sizes 6 AWG or Smaller. An insulated grounded conductor of 6 AWG or smaller shall be identified by one of the following means: 
  
  (1) A continuous white outer finish.
  
  (2) A continuous gray outer finish. 
  
  (3) Three continuous white or gray stripes along the conductor's entire length on other than green insulation. 
  
  (4) Wires that have their outer covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section.