Re: CQD answer published Friday, July 22, 2016 -Utility Overcurrent Protection
I couldn't let the statement stand, "the overcurrent protective device is typically on the primary side of the utility transformer." Most electric utilities do not install an overcurrent protective device for the transformer but it is there to protect the primary line that feeds the transformer. We expect the downstream fault to "burn open" and keep the rest of our customers in service. The overcurrent protective device (normally a cutout and fuse) is to open in the case of a fault in the transformer or one on the load side of the transformer if the fault is very close to the transformer. No one can ever rely on the overcurrent protective device on the primary side of an electric utility's transformer to protect their service entrance conductors.
Take care, Charlie Eldridge, Consultant