Power now restored to about 62000 homes in Hawke's Bay and ...

Sungmi Kim/Stuff

Transpower has been working with lines companies Unison and Eastland to reconfigure electricity distribution in the region, but warns there are limits to the workarounds.

Transpower says power has now been restored to about 62,000 homes in Hawke’s Bay and Gisborne as a result of efforts to re-route power around its crippled Redclyffe substation in Napier.

Many people are still without power, but the national grid operator said it hoped to progress work to reconnect more homes and businesses on Thursday.

Transpower gained access to the Redcliffe substation on Wednesday and confirmed it had been flooded.

The substation had fed power into most of the region prior to arrival of Cyclone Gabrielle and Transpower said it was now assessing the damage.

Despite the progress restoring power, Transpower has indicated that there is a limit to the workarounds it can put in place, meaning there is still a possibility that some people could be without power for days or weeks.

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Transpower previously announced late on Tuesday afternoon that it had be able to supply Hastings-based Unison Networks with enough power to supply about 17,000 homes by re-routing power from the grid through a different substation at Fernhill.

It also said then that it had also been able to supply Gisborne-based Eastland Networks with 10 megawatts (MW), or enough power for 10,000 homes, by re-routing power from Genesis’ Tuai hydro power station on Lake Waikaremoana.

In an update on Wednesday afternoon, it said Unison had now been able to reconfigure its network to take enough power to reconnect a total of about 38,000 homes.

It was also now supplying Eastland with enough power to supply about 24,000 homes, it said.

Eastland was taking 24MW of the 30MW of power Transpower could potentially supply “indicating they have ongoing damage to their network preventing them from reconnecting additional customers”, it said.

Spokesperson Nathan Green said Transpower was working on a plan to bypass the Redclyffe substation and bring power to its Whakatu substation to enable Unison to reconnect more homes and businesses.

“We expect to be able to provide a further update on that work tomorrow,” he said.

Transpower looks likely to face questions over the vulnerability of the Redclyffe substation.

Chief executive Alison Andrew told RNZ the substation was designed in 1927 and refurbished in the 1970s and was designed to withstand a “one in 100 year” flood.

But she revealed Transpower had since been building some substations to a higher standard, saying one built in Auckland in 2013 had been designed to withstand a “one in 450 year” flooding event.

Transpower had sought permission from the Commerce Commission to invest $100 million on upgrades between 2025 and 2030 that would improve the resilience of its networks, she said.

Transpower could not immediately confirm whether that included work that would reduce its reliance on the Redcliffe substation.

The state-owned enterprise needs permission from the competition regulator for such investments because of the way it is regulated and charges customers.