Where in the NEC does it define the wire size when bonding the ?X0? of Delta / Wye to ground?
In my example I have a 390 KVA 480 : 480/277 transformer. A Neutral is required on the secondary of the transformer for some 277Vac heater circuits. The secondary of the transformer has Buss-Bar to which ?X0? is attached, we bond the transformer case to building steel and pull (3) Hot legs a Ground and Neutral (5 Cables) to the Heater Enclosure. Also, inside the transformer we bond/connect the Buss-Bar (?X0?) to point where the transformer case has been grounded to building steel. Thus connecting Ground and Neutral together; inside the Heat Enclosure the Ground and Neutral cable land on their own distribution block, but are electrically at the same potential at this point.
It looks like in this case 2 x ((4) 350MCM w/ a 1/0 ground) were run in a 2 x 3? conduits.
What wire size should used inside the transformer between X0 (Buss-Bar) and Ground?
In my example I have a 390 KVA 480 : 480/277 transformer. A Neutral is required on the secondary of the transformer for some 277Vac heater circuits. The secondary of the transformer has Buss-Bar to which ?X0? is attached, we bond the transformer case to building steel and pull (3) Hot legs a Ground and Neutral (5 Cables) to the Heater Enclosure. Also, inside the transformer we bond/connect the Buss-Bar (?X0?) to point where the transformer case has been grounded to building steel. Thus connecting Ground and Neutral together; inside the Heat Enclosure the Ground and Neutral cable land on their own distribution block, but are electrically at the same potential at this point.
It looks like in this case 2 x ((4) 350MCM w/ a 1/0 ground) were run in a 2 x 3? conduits.
What wire size should used inside the transformer between X0 (Buss-Bar) and Ground?
