Grounding secondary service transformer from underground pvc to cable tray

[kentwc]

We are installing a 3750KVA transformer that is 12470 Delta to 480Y/277. We are going to two 2000 amp main distribution panels. We are going to run 5-600mcm cables per phase but had a question on the grounding side of things. We are running under ground for about 20 feet with 10-3 1/2" PVC conduits up to a cable tray that will run the remaining 110 Ft. Do we have to run a 250mcm grounding conductor in each race way to grounding lugs on the cable tray and then run two 250mcm grounding conductors the remaining way in the cable tray, which one will land in each distribution panel?

In the drawing it shows the transformer underground conduit and the cable tray.
Thanks in advance!!

 

[don_resqcapt19]

It appears to me that the conductor in question would be a supply side bonding jumper and not an EGC. If that is the case the conductor in each raceway would only need to be a 1/0. See 250.102 and Table 250.102(C)(1).

 

[kentwc]

It appears to me that the conductor in question would be a supply side bonding jumper and not an EGC. If that is the case the conductor in each raceway would only need to be a 1/0. See 250.102 and Table 250.102(C)(1).

Thank you I agree. I think I was looking at this all wrong and was thinking of EGC which is where I was coming up with the 250kcmil. I was not thinking supply side bonding jumper. So I could run 1/0 in each raceway and continue the 1/0 for each parallel run through the cable tray into my main distribution panel. Thanks for the help!