Subsea Cables & Internet Infrastructure

A shunt fault is damage to the insulation around the power conductor that all subsea cables require for undersea optical amplification. It causes an electric short. They are most common in the deep sea where the cable lies exposed on the sea floor as opposed to near shore where burial is routine. Abrasion caused by deep sea currents that rub cables against sharp surfaces like rocks are the usual suspects. Depending on the extent of the abrasion, a shunt fault may or may not cause an outage. It depends on the ability of off-shore power facilities to compensate for a partial loss of voltage. When I was worked at Hibernia Atlantic, our cables experienced shunt faults that did not disrupt service. A cable ship would be dispatched to fix it. Below is a shunt fault on Subco's Oman/Australia cable. You can see the power burns on the eroded insulation.