Ground Fault at 208V switchboard

[kimseunghee]

The lighting switchboard is derived via 480V/208V transformer from 480V main switchboard. The transformer is DYn and the secondary is solid grounded.
I'd like to use 208V line-line voltage to small motor and 120V phase-neutral to lighting fitting each.
Both feeder breakers on lighting switchboard(208V,3ph) will open against ground fault ?

 

[alehman]

You don't show the transformer neutral being connected to ground (which it normally must be). If the neutral is grounded, the branch circuit breakers will open for ground faults.

 

[davidbeach]

In NEC land, to serve line to neutral loads, the neutral must be solidly grounded. No ifs, no ands, no buts. With a solidly grounded neutral circuit B would only need a single pole breaker. Also, in NEC land, there are very few, extremely specialized, exceptions to the rule that a 208Y system shall be solidly grounded.

Elsewhere in the world other rules may apply, but your voltages strongly suggest that the NEC or a very similar code will govern.