Is this required

[Tulsa Electrician]

Are you sizing the EGC from the potential full size wire for amperage or the parallel conductor size?

If I understand the question correctly. The math I used was based to minimum size required for a 400 amp feeder with a 400 amp OCPD. Compared that to the one line which showed 350 mcm and two sets each in there own raceway.

I choose a 3/0 for each parallel set with an ampacity of 200 amps @ 75c.

Then I went to 250.122 table for the minimum EGC for a 400 amp OCPD.

I used copper conductors since the drawing showed cu.

With a minimum of 3/0 in each raceway and each raceway requires a full size EGC. I then came up with a ratio between 2- 3/0 cu and 2- 350's

Then took the CM of the #3 and multipled it by the ratio. This gave me the minimum CM required.
Then choose the CM that equals that number or the next one up. You can not round down.

So to ansawer your questions, yes and yes
Or: I'm sizing the EGC from the potential (listed) full size wire (2-350) for the amperage (400) of the OCPD listed for the paralleled sets(2) each set in there own raceway using a cu conductor.

Then size your raceway or at least check to be sure it is sized correctly. In this case it is, 40% fill for sch 40 PVC=2.907 and the conductors add up to 2.1941 based on chapter 9 NEC

 

[NEC_NERD]

Those conductor sizes may not be required by the NEC, but if they are in the contract documents then they are required for the project.

100% agree. Ran into this on many of my multi-family jobs. Redline drawings dictate almost everything on the job.