Correlation between the two outages

Q: The same customers have been hit twice. Are these outages linked?
A: No. The two events are unrelated.

  • The first outage (31 October) was caused by a tree falling on the 33kV line to Mount Pokaka.
  • The second outage (6 November) was due to an equipment failure inside the Kaikohe substation that damaged part of the 33kV switchboard. This is being investigated.

Kaikohe outage 6 November

Q: What went wrong?
A: Around 5.20pm, an equipment failure inside the Kaikohe substation caused a major outage affecting about 23,000 customers.

  • A protection breaker catastrophically failed, which triggered the fire suppression system and damaged part of the 33kV switchboard.
  • The failure caused significant arcing and heat but no fire and no widespread physical damage, but:
    • Half of the 33kV switchboard is out of service.
    • We are currently running on our smallest transformer at Kaikohe.
    • Ngāwhā generation is offline for planned annual maintenance, so we don’t have our usual backup
    • We’re using diesel generation at Omanaia to help support the southern part of the network.
    • An investigation is underway to confirm the cause and any contributing factors.

Prevention

Q: Was this a result of poor maintenance or negligence?
A: The outage was caused by unexpected equipment failure of the 33kV switchboard

The damaged 33kV switchboard is approximately10 years old, they have a normal life of about 50 years. All our electricity equipment is maintained in line with industry standards, manufacturers’ recommendations, and our asset management plans.

If our investigation identifies anything that needs to change, we will act on it.

Compensation and liability

Q: Will customers be compensated for food loss, business disruption or inconvenience?
A: No additional compensation is being offered for this event.

We appreciate this outage has been disruptive and frustrating, especially coming so soon after the earlier event. We encourage people to contact their insurance company.

Customers are welcome to contact us directly if they believe there are exceptional circumstances in their case, and we will review those individually.

Q: What responsibilities does the equipment supplier have if the equipment is found to be faulty?

A: If our investigation confirms a fault with supplied equipment, we’ll work through our contractual rights and obligations with the manufacturer, including repair or replacement and any required design or maintenance changes.

Security of Supply

Q: Are further outages likely?
A: No electricity network can ever be completely outage free – faults from weather, trees, vehicles, or equipment can still happen on any system. We are doing everything we can to reduce the likelihood and impact and to strengthen the resilience of supply.

In regard to the current situation:

  • The system is operating safely, but with less backup than usual.
  • We’ve brought in diesel generation at Omanaia to help support the southern network.
  • We’re asking customers to use electricity prudently, especially during morning and evening peaks, to avoid unnecessary stress on the system.

Q: When will the switchboard and full backup be restored?
A: We are currently:

  • Confirming the full extent of the damage,
  • Working with the equipment supplier to source or manufacture replacement components, and
  • Planning the repair and commissioning programme.

Until this work is complete, we will:

  • Continue to operate the network conservatively,
  • Use diesel generation where needed, and
  • Keep stakeholders and the community updated on progress.

We’ll share indicative timeframes once we have reliable information.

Back up generation – Ngāwhā Generation

Q: Why wasn’t Ngāwhā operating?
A: Ngāwhā is offline for its planned annual maintenance, which is essential to keep the plant reliable and safe over the long term.

Planned maintenance is scheduled carefully and based on normal operating expectations. The equipment failure at Kaikohe was not expected and occurred while that maintenance was underway. Together, these factors have reduced capacity, and that’s why we’re being extra cautious and asking customers to conserve power.

Q: When will Ngāwhā be back online?

A: It is expected that Ngāwhā will be fully operating again by the end of next week, we are seeing if there is a possibility of bringing it back on stream earlier.

Mount Pokaka 33kV line – 31 October

What happened?

  • Around 4pm, a tree fell onto the 33kV line to Mount Pokaka, cutting supply to around 23,000 customers.
  • The primary protection for the line didn’t operate as expected, so the backup protection tripped the rest of the substation, causing a wider outage on all of the lines.
  • Crews removed the tree, inspected the line, and restored power.