gec at existing structure

[buddhakii]

I'm doing an upgrade to an existing waste water facility and I'm looking for a little advice on how to make the ges work. Situation is an existing concrete structure with water channels in it that got re-worked to add channels in some areas and fill in others. There is an existing building on one end of the entire concrete structure. On the other side one of the channels there is a new building going up and I have two 480 volt feeders going into a new electrical room in that building. One is for a 400 amp panel and the other goes to a transformer feeding a low volt panel. Both feeders come out of the existing building. Imo this is all the same structure so I would just need a gec for the transformer, however the prints do call for a gec to the 400 amp panel as well. There is a ground ring that the gc dug up and I have to repair which is running just outside of the electrical room. I'm pretty sure the Main Switch gear ties to this but I'm not positive. Would you just run to this or should I try to get something in the slab from the existing building? Appreciate any feedback.

 

[gndrod]

I'm doing an upgrade to an existing waste water facility structure
There is an existing building on one end of the entire concrete structure. On the other side one of the channels there is a new building going up

Both feeders come out of the existing building. Imo this is all the same structure so I would just need a gec for the transformer, however the prints do call for a gec to the 400 amp panel as well.
Would you just run to this or should I try to get something in the slab from the existing building? Appreciate any feedback.

Does the existing concrete structure have a UFER and is the one channel integrally tied in with the new building if this is an entire concrete structure? A UFER gec tie-in to the panel is sufficient.

 

[tom baker]

You could tie both the ground bus and the transformer ground to the ground ring but an AHJ may not allow this as there is no way to determine if the ground ring is intact.
Just follow 250.50 and create the grounding electrode system - water, rebar, structural metal, If you don't have any of those you'll need one or two ground rods.