fault occurred in the shore joint of Cable 1 at Fighting Bay. August 1975 – A strong wind storm caused a string of seven transmission towers to collapse and damage the line. The link took five days to repair. 1976 – A fault occurred at the Cable 1 undersea joint, 15.5 km from the South Island end at a depth of 120 metres. The joint was repaired in 1977. 1980 – Cable 3 failed at the Fighting Bay shore joint. 1981 – A gas leak on Cable 1 occurred at Oteranga Bay. It was repaired in the 1982/83 summer. 1988 – Cable 2's Oteranga Bay end joint exploded, spilling insulating oil into the switchyard. 2004 – In January, three HVDC towers collapsed as a result of extreme winds, and in August the line voltage had to be reduced for long periods because of insulation flashovers caused by severe salt pollution at the cable station at Oteranga Bay. In October, a fault occurred in one of three Cook Strait cables that reduced the Pole 1 capacity from 540 MW to 386 MW. Repairs took almost six months. 19 June 2006 – The link experienced an unplanned outage just before the evening peak period on one of the coldest days of the year. With four North Island power stations out for service and an outage of Tauranga's ripple load control equipment, even with the reserve Whirinaki Power Station called upon, the North Island experienced electricity shortages and Transpower subsequently declared a nationwide Grid Emergency at 5:34 pm. The link was restored shortly after the emergency was declared. 28 August 2008 – A transmission tower in the Marlborough Sounds was found buckled after its foundations slipped. The tower was reinforced with steel guy ropes until it could be replaced, as the link couldn't be shut down without causing widespread power shortages in the South Island. 12 November 2013 – During the commissioning of the new two-pole control systems, a test to assess the control's response to a trip on a 220 kV line out of Haywards during high north flow caused three filter banks at Benmore to trip off the grid. The HVDC controls automatically cut northbound transfer from 1000 MW to 140 MW, causing automatic underfrequency load shedding (AUFLS) systems to deploy in the North Island, and blacking out thousands of customers. A software bug was found to be the cause of