wireman1
Senior Member
a 100 kva transformer 480 volt 3 phase step down transformer is going to fed a service panel with 208 /120 volt 3 phase .if you ground and bond at x0 terminal in the transformer is the panel now considered a sub panel and you isolate the grounds and neutrals . but if bond and ground in the panel and land the grounds and neutrals on the same bar is it considered a service . what do you do with the x0 terminal in the transformer just bond it to the frame of the transformer. because you cant bond and ground in both the transformer and the panel which of the above is mostly widely used? also which articles would apply and is this considered a separately derived system.