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Rolling outage process following instructions from Transpower

From time to time Transpower can issue instructions for electricity distribution businesses, including Vector, to shed power because of issues with the wholesale market or Transpower’s transmission system.

This is a requirement that we have to comply with under the rules of the energy market and our process for how we manage these requirements is set out below.

When Transpower directs us to begin rolling outages, our aim is to manage the disruption to customers across Auckland as fairly and equitably as we can, avoiding critical areas such as hospitals.

What are rolling outages?

Rolling outages are temporary, planned electricity disconnections, spread over different parts of Auckland and at different times. They are used to reduce the consumption of electricity, while avoiding leaving anyone without power for a prolonged period.

Why do we have rolling outages?

They are rare but may be needed as a last resort to manage severe energy supply shortages. This is when the supply of electricity is too low to meet demand. Having well-planned, shorter, temporary outages will help to prevent unpredictable, longer, widespread blackouts.

Who decides when rolling outages are needed?

Severe energy supply shortages can be caused by a number of different factors, for example a very cold night creating exceptional demand, a major failure on Transpower’s transmission network, insufficient electricity generation, or a combination of these. 

Transpower is responsible for assessing these factors and making the decision to cut power; it then directs Vector, and other electricity distribution businesses around the country, to begin rolling outages.

How long do the outages last?

It depends on the severity of the event, but Vector tries to keep the outage in each area as short as possible – aiming for no longer than four hours at a time in each location. But this will depend on the level of savings required by Transpower.
Vector does this by organising a series of outages, beginning in one location for a set period, then moving to the next and the next, until Transpower says the rolling outages can end. Because demand varies from day-to-day, the time and extent of outages notified to customers will be approximate.

How are the locations chosen?

We consider a number of factors including:

• Prioritising demand: we have a priority list that aims, where possible, to protect critical health and infrastructure services, such as areas with major hospitals, air traffic control centres, emergency operation centres, communication networks, and water and sewage pumping.

• What else is happening on the network: including areas where planned outages are already underway or unplanned outages have occurred

What about vulnerable customers?

We give electricity retailers as much advanced notice as possible of which areas will be affected by rolling outages, so they can notify medically dependent customers, who rely on electricity for life-sustaining equipment. However, we may get little warning from Transpower about the start of a rolling outage, so these customers should always have a backup plan in place as it is not possible to prioritise their supply.

What about other customers?

We will try to give customers as much notice as possible but, again, this depends on how much warning we get from Transpower. Our communication may include through email and text messages, updates on our website, through our call centre, community engagement, key account managers, via the media and on our social media pages.

How do I prepare for a rolling outage?

As with any power outage, it always helps to be prepared: read our tips here (see ‘how can I prepare for an outage at home’ and ‘how can I prepare my business or community for an outage’)

More information

See Vector's participant rolling outage plan, which has been approved by the System Operator.