Supply-side Bonding Jumper Vs Grounding Rod

[alabaza]

Hello Folks,

I am having a debate between using a supply-side bonding jumper or a grounding rod for my main distribution panel. I have an outdoor 4.16-204KV-208/120V, 75KVA pad mounted transformer feeding an outdoor 3 Phase, 225A main panel mounted on a unistrut to feed sports field lighting. The panel is located about 12 feet away from the transformer. The code gets confusing when it calls for a supply-side bonding jumper 250.30 A(5)for a single separtley derived system; now this usually applies for a dry type transformer inside a building but still i couldn't find where it says that it can't be used for an outdoor pad mounted transformer, while 250.24(A) shows the use of an extra grounding rod by the main panel instead of a supply-side bonding jumper connected to transformer grounding rod. Now which method can i use, or can both methods be used?
one grounding rod by the transformer and a supply-side bonding jumper from panel to transformer OR
Two grounding rods, one at the transformer and one by the panel?

thank you for the input

 

[trosepe]

The bonding jumper and grounding electrode connection are two separate requirements. The bonding jumper from the separately derived neutral to the equipment enclosure can occur at either the transformer or the first over current device on the transformer secondary. For this type of installation we typically bond the neutral at the transformer. We then install two ground rods 10' apart bonded together and then also connected to the transformer and panel enclosure. This way you satisfy the 25 ohm or less requirement and you ensure a well grounded system.