The major power outage of 2015: 5 lessons for grid operators

What happened

The outage was caused by a combination of a technical defect and human error at a high-voltage substation of grid operator TenneT near Diemen. Within a short time, a large part of the grid in Noord-Holland and Flevoland went down.

The original fault at the substation was resolved after around an hour, but it took until the middle of the afternoon before the power was back everywhere. It was not only homes that were without power; businesses, hospitals and public transport were also affected. Afterwards, the Inspectie Veiligheid en Justitie and the then Agentschap Telecom investigated the crisis management and the telecommunications. One of the most important conclusions concerned the dependency on telecoms.

Lesson 1: Count on telecoms failing

When the power failed, the mobile network also started to falter after a while. Transmission masts have only a limited emergency power supply. As a result, calling and using the internet became more difficult at the very moment people were looking for information.

For a grid operator this means: count on your own channels and those of your customers potentially failing. Ensure a communication infrastructure that keeps working even during an outage, and coordinate in advance with the safety regions and telecom parties. A status page that runs on independent infrastructure remains accessible to anyone who is still online.

Lesson 2: Give an honest picture quickly, even without all the answers

During a large-scale outage, everyone wants to know the same things: what is going on, how long will it last and what should I do? At the start, the restoration time is often still uncertain. Do not wait for it: give an honest first message quickly and update it at set moments.

Communicate what you do know (the affected area, the fact that you are working on restoration) and be clear about what you do not yet know. In this way you keep people's trust and prevent rumours and disinformation from taking over the picture.

Lesson 3: Give vulnerable and critical customers priority

Not every customer is the same. Some parties need direct help or specific information.

• Hospitals and care institutions, which switch to emergency power.
• Other critical sectors such as drinking water, telecoms and payment services, which depend on electricity.
• Vulnerable residents, for example people with home care or medical equipment.
• Traffic and public transport, where an outage immediately leads to a safety risk.

Lesson 4: Work as a chain, with a shared picture

A major power outage is never the concern of one party alone. The grid operator, TenneT, the safety regions, municipalities and emergency services must all have the same picture at lightning speed. In 2015 it became clear that coordination between all those parties takes time, precisely when the usual means of communication are faltering.

So agree in advance how you will scale up, who communicates about what and how you share information. A single shared crisis picture, in which facts, decisions and messages are visible to everyone, prevents parties from working at cross purposes.

Lesson 5: Know your reporting obligations (NIS2 and CER)

Grid operators are essential entities. Since 15 August 2026, two laws have applied alongside each other: the Cybersecurity Act (NIS2) for digital resilience, and the Critical Entities Resilience Act (CER) for physical and all-hazards resilience. An incident that significantly disrupts your services must be reported within 24 hours; supervision lies partly with the Rijksinspectie Digitale Infrastructuur (RDI).

In addition, the rules from the energy crisis plans apply (such as the Electricity Protection and Restoration Plan) as well as the compensation scheme for customers in the event of a prolonged interruption. During the crisis, record which reports were made when and to whom.

How CrisisRadar helps

CrisisRadar gives grid operators and energy companies a single shared crisis picture, together with TenneT, the safety region and municipalities. You record facts with their source, prioritise vulnerable and critical customers, draw up an outage message within minutes and publish the current status and expected restoration time on your own status page. The status page runs separately from your core systems, so that communication keeps working even during an outage. Reporting-obligation timers keep track of the deadlines.

Would you like to see what a large-scale power outage looks like step by step in the platform? Then take a look at the accompanying practice scenario.

Stappenplan

Veelgestelde vragen

What was the cause of the power outage of 27 March 2015?

The outage was caused by a combination of a technical defect and human error at a high-voltage substation of TenneT near Diemen. More than a million households in Noord-Holland and Flevoland were without power.

Why is a power outage also a communication problem?

During a prolonged power outage, the mobile network also fails after a while, because transmission masts have only limited emergency power. Precisely when people are looking for information, communicating becomes more difficult. That is why grid operators must count on telecoms failing and prepare communication on independent infrastructure.

Which reporting obligation applies to grid operators during a major outage?

As an essential or critical entity, you report a significant disruption within 24 hours under the Critical Entities Resilience Act (CER); cyber incidents fall under the Cybersecurity Act (NIS2), with a report to the NCSC. Supervision lies partly with the RDI.