Separately Derived Systems bonding/grounding NEC 250.30(A)(1) and 250.30(A)(2)

[Isaiah]

I just want to double-check with the 'grounding gods' out there before I raise a red flag on this apparent violation of 250.30(A)(1) and 250.30(A)(2).
Client's std detail (separately derived systems), shows NO direct connection between the ground and neutral buses, either at the Panelboard, (system bonding jumper) or at the transformer (supply side bonding jumper). The scenario is for a typical 3 ph 4W lighting panelboard and Xfmr, 480-208/120V, 30kVA, delta-wye, solidly grounded.
Panelboard Ground bus has a green conductor that bonds to the case and goes directly to the main ground loop; the Panelboard Neutral bus has a white conductor that goes directly back to the transformer XO.

 

[infinity]

Client's std detail (separately derived systems), shows NO direct connection between the ground and neutral buses, either at the Panelboard, (system bonding jumper) or at the transformer (supply side bonding jumper).

There needs to be a system bonding jumper at either the transformer or at the panel but not both.

 

[Isaiah]

There needs to be a system bonding jumper at either the transformer or at the panel but not both.

Thanks Infinity, exactly as I thought.

 

[tom baker]

And connection to a grounding electrode system. The GES connection is done where the SBJ is installed.
If you install the SBJ at the transformer, its a 5 wire connection to the panel. If the SBJ is installed a the panel, then its a 4 wire connection to the transformer. Most often the SBJ for over 5 KW is done at the transformer. For the 4 wire system the neutral and EGC are combined into one wire so there is a minimum size.

If you make the SBJ connection at both locations you will have a parallel path for neutral current, violation of 250.6, and all kinds of odd things can happen.

for your clients std detail, the SBJ is all about getting fault current back into the windings of the transformer. with out it, a line to case connection fault would not clear.