Neutral to Service

[augie47]

Sometimes my mind questions my mind.
Situation: 2000 amp service, fed by (6) runs of 500kcmil Cu. No Neutral load.
Pad has a neutral so I know from 250.24(C) that I have to install a neutral to my service gear. If I read correctly, the neutral in each conduit must be 375 kcmil (12-1/2% of sum of ungrounded conductors). Am I correct?

 

[charlie b]

Pad has a neutral so I know . . . . Am I correct?

The pad can't have a neutral ? it's made of concrete.

But what type of service is this? Is it one of the ones listed in 250.20(A) to (E)? If not, if for example this is a 480 volt delta secondary, then you don't need a neutral.

If you do need a neutral, then I read 250.24(C) as saying you only need a 1/0 in each conduit. Unlike EGCs, the neutral in each conduit does not have to be a "full size" conductor. The circular mil area of each phase conductor in each of your conduits is 500 MCM. Table 250.66 says you would only need a 1/0 GEC for that size service conductor. 250.24(C)(1) says to base the size of the neutral on 250.66.

 

[kturner]

250.24(B)(2) says where installed in two or more raceways, the size of the grounded conductor in each raceway shall be based on the size of the ungrounded service-entrance conductor in the raceway but not smaller than 1/0 AWG. Therefore, this installation, with 500 mcm ungrounded conductors per raceway, would require a 1/0 neutral per raceway according to Table 250.66.