Firstly, when sizing the equipment grounding cable at the service entrance, we usually follow the Table 250-66.
However, I can not quite define the service entrance. I am still wondering which table(Table-66 or Table-122) should be applied the drawing what I am doing.
For example, a transformer is owned by customer, does the service entrance begin from primary side of transformer or the other point?
Someone says that if OCPD is installed the place, we have to apply Table 250-122 .
Thanks in advance
However, I can not quite define the service entrance. I am still wondering which table(Table-66 or Table-122) should be applied the drawing what I am doing.
For example, a transformer is owned by customer, does the service entrance begin from primary side of transformer or the other point?
Someone says that if OCPD is installed the place, we have to apply Table 250-122 .
Thanks in advance