The 2006 Auckland Blackout was a major electrical blackout in

Auckland Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...

, the largest city in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, on 12 June 2006. It started at 08:30 local time, with most areas of Auckland regaining power by 14:45 local time. It affected some 230,000 customers and at least 700,000 people in and around the city.

Immediate effect

Power went off at around 8:30 am local time on 12 June 2006 over half of Auckland in New Zealand. Most of southern and central Auckland, including the central city were without power.

Cause

The cause of the blackout was traced back to the Otahuhu sub-station, the city's main transmission switching station. A corroded

shackle A shackle (or shacklebolt), also known as a gyve, is a U-shaped piece of metal secured with a clevis pin or bolt across the opening, or a hinged metal loop secured with a quick-release locking pin mechanism. The term also applies to handcuffs ...

connecting the Otahuhu to Penrose 220 kV line's earth wire had broken in winds, letting the earth wire fall across the 220 kV line and the 110 kV busbar below it, tripping both the line and three sections of the busbar, disconnecting lines to Mount Roskill, Penrose and Pakuranga. The trip also disconnected Otahuhu B and Southdown power stations from the national grid. The trip left only one line, the now-dismantled Arapuni to Pakuranga 110 kV line, supplying Pakuranga, Penrose, and the central city. Eight seconds after the failure, this line tripped from overloading, leaving Penrose, Pakuranga, and central city substations without power, as well as parts of Otahuhu and Mount Roskill substations. Investigation of this incident found that maintenance of the electricity transmission system was not adequate and that this substation had major and minor design deficiencies.

Effects

Due to the power outage, many public services and business operations were disrupted: * suburban commuter railway services were suspended * over 300 groups of traffic lights were off * some hospitals were closed and left only emergency services in operations * radio station transmitters located in the

Sky Tower Sky Tower, SkyTower, Skytower, or Sky Towers may refer to: Buildings In Asia * Higashiyama Sky Tower, Nagoya, Japan * Marina Sky Towers in Dubai, UAE * Sky Tower (Abu Dhabi) in Abu Dhabi, UAE * in Kowloon, Hong Kong * in Dubai, UAE * Sky Tower ...

were also taken offline for a period of time * mobile phone and telephone service failures * people stuck in lifts in office buildings * end of semester exams due to be held that day at local universities were postponed. Since the central city was without power from the morning rush hours, business operations and traffic were disrupted severely. Many businesses sent their staff home.

Restoration of service

Power was restored to

central at 12:40 local time, 12 June 2006. It was estimated that all affected areas would have their power restored by 16:30 local time. At approximately 14:45, power was restored to most of Auckland, except Penrose, Glen Innes,

East Tāmaki East Tāmaki is a suburb of Auckland, New Zealand. It is a largely industrial area adjacent to a rapidly growing population. Prior to the 1960s it was largely a dairy farming area. A landmark is Smales Mountain which in 2010 has the remains of ...

, and

Ōtāhuhu Ōtāhuhu is a suburb of Auckland, New Zealand – to the southeast of the CBD, on a narrow isthmus between an arm of the Manukau Harbour to the west and the Tamaki River estuary to the east. The isthmus is the narrowest connection between the ...

Improving security of supply

The incident at Otahuhu in June 2006 had a major influence on subsequent decisions about the development of the grid. On 11 December 2006, the

Electricity Commission (NZ) The New Zealand Electricity Commission was a government authority set up in 2003 to regulate the electricity sector in New Zealand. It was succeeded by the Electricity Authority in November 2010. The Commission was established under the Electri ...

received an application from Transpower for the establishment of a new 220 kV gas insulated switchgear (GIS) facility at Otahuhu, adjacent to but geographically separate from the existing outdoor 220 kV switchyard. This project was described as the Otahuhu substation diversity project, and included transferring approximately half of the circuits from the existing switchyard to the new GIS switchyard, to improve network resilience. The project was approved in August 2007. Further steps have been taken to increase security of supply to Auckland, by reducing the dependence on Otahuhu. These include the diversity provided as part of the North Island Grid Upgrade Project by connecting the new

Whakamaru to Brownhill Road transmission line The Whakamaru to Brownhill Road transmission line is a double-circuit 400 kV-capable transmission line constructed by Transpower to increase the capacity of the National Grid between the southern Waikato and the city of Auckland. The line r ...

Pakuranga Pakuranga is an eastern suburb of Auckland, in northern New Zealand. Pakuranga covers a series of low ridges and previously swampy flats, now drained, that lie between the Pakuranga Creek and Tamaki River, two estuarial arms of the Hauraki Gul ...

substation, rather than directly to Otahuhu. A second major project, the

North Auckland and Northland grid upgrade project The North Auckland and Northland (NAaN) grid upgrade project reinforced transmission into the Auckland Region and across the harbour to North Auckland and the Northland Region. It added new 220 kV transmission capacity to the National Grid ...

provides underground 220 kV cables from Pakuranga to Penrose, and from Penrose to Albany on the North Shore, via Hobson Street in the Auckland CBD. A 220 kV- capable overhead transmission line between Pakuranga and Otahuhu has also been upgraded from 110 kV to 220 kV.

References