Neutral sizing

[Pelectric1985]

On the job site we are at now we have four panels that are three-phase and 480 volt. The panels have no neutral load. They are servicing only three-phase air-conditioning equipment. The panel that is the longest distance away is 650 feet from the MDP And calculated for the voltage drop of 97 AMP's running 3/0 wire. The question is : Because they are panels do I have to have a neutral in them And what size even though there is no neutral load? My interpretation is that I do have to have the neutral in each of the four panels but it can be sized in table 250-122 Because it has to be no smaller than the grounding conductor Which also must be increased as phase conductors were because of voltage drop. What Is your input on this?

 

[texie]

On the job site we are at now we have four panels that are three-phase and 480 volt. The panels have no neutral load. They are servicing only three-phase air-conditioning equipment. The panel that is the longest distance away is 650 feet from the MDP And calculated for the voltage drop of 97 AMP's running 3/0 wire. The question is : Because they are panels do I have to have a neutral in them And what size even though there is no neutral load? My interpretation is that I do have to have the neutral in each of the four panels but it can be sized in table 250-122 Because it has to be no smaller than the grounding conductor Which also must be increased as phase conductors were because of voltage drop. What Is your input on this?

There is no requirement to have a neutral if you have no line to neutral loads. You are correct that IF you do provide a neutral, the minimum size would be per Table 250.122 or the calculated load, whichever is greater.

 

[charlie b]

A service panel must have a grounded (i.e., neutral) conductor, per 250.24(C). No other panel is required to have a neutral brought to it, if there are no loads that require a neutral.