Sizing EGC on 225kVA Transformer?

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I'm trying to size the secondary side Equipment Grounding Conductor in a 225 kVA, 480V primary, 120/208V secondary to feed an 800A3P panel. I sized the secondary conductors to be 4 parallel sets of #3/0 copper wire, which is good for the 800A.
Now here is where I'm confused: Article 250.122(F) says "Each equipment grounding conductor shall be sized in compliance with 250.122." My first instinct is to use 4 parallel sets of #6 copper for the EGC because each one is good for 200A (in my mind, four of the EGCs good for 200A should be good for 800A) which I'm pretty sure is wrong because someone on this board said in an earlier topic that you cannot combine multiple small EGCs to make a larger EGC. I am also aware that article 310.10(H)(1)says that I cannot have parallel conductors smaller than 1/0 in each raceway.
So do I need 4 parallel sets of #1/0 AWG for my EGC? Having 4 parallel sets of #1/0 AWG EGCs for the feed to this 800A panel seems excessive since Table 250.122 indicates that one #1/0 AWG copper is good for 800A. Having 4 parallel sets of #1/0 seems like too much.
 
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infinity

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The conductor(s) between the transformer and the panel would be a SSBJ(s) (supply side bonding jumper). For parallel raceways you would use one in each raceway sized according to 250.66 based on the size of the conductors within the raceway. For #3/0 cu that would a #4 cu SSBJ in each raceway. Bonding jumpers connected in parallel can be smaller than #1/0.
 
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infinity

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You're welcome. :)

These things are confusing because of the different terminology and where to find each term in the codebook. Knowing what you're looking for is half the battle. :cool:
 

kwired

Electron manager
Location
NE Nebraska
Oops typo, 250.66. Also look at 250.102(C).
Assuming by the line at bottom of your posts you are referring to 2011 NEC.

2014 you still go to 250.102(C) but they have added a table (Table 250.102(C)(1)) that is almost identical to table 250.66 instead of sending you to 250.66.
 

kwired

Electron manager
Location
NE Nebraska
Yup. :)

The 2014 does clean it up a bit.
There is another current thread that I bring up whether it was necessary to have a second table that is nearly identical to 250.66. The tables are identical except for the bottom row and some differences in notes, but in general no requirements were changed, you should still come up with same sized conductor in any case whether you are using 2011 or 2014.
 
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