Is this a dry-type SDS transformer?
Our practice has been to run a slightly oversized grounding bond in the feeder to the XFMR. It tags the Xo, the chassis. The derived power pulls it's neutral from the Xo and bonds via lazy-lugs up to the first disconnect -- typically a circuit breaker in a surface mount 3-phase panel near by.
Bonding to the GEC and steel and utilities occurred back at the MAIN distribution box, the SERVICE.
But you don't have to do it that way. If you're bonding to steel and utilities do expect to have inspection hatches -- and to avoid breaks in the SDS GEC.
