I'll chime in here. If you decide to reduce the neutral I want calculations and no rule of thumb or trade practice is acceptable in determining the correct size.
Second. If you run parallel in more than 1 raceway then 2 neutrals are going in. 1 for each pipe. See 12-108 for parallel runs. If you can reduce the neutral you can divide the ampacity and install 2 conductors smaller than 1/0 to provide the neutral but there must be a neutral in each pipe as well as bonding conductors if the raceway cannot be used as a bonding method like when using PVC. As stated the rule for reducing neutral is 4-022. Reducing the neutral for resistive 240 volt loads makes sense especially in residential applications where harmonics are almost a non- existent problem.
Last edited by mikesh; 07/16/08 12:20 PM. Reason: add information
