On 4 July 2025, shortly before 12:00 CEST, an incident occurred in the Czech power system which led to significant outages in the eastern and northern part of the Czech Republic including areas of Prague.

Based on the preliminary information shared by the Czech transmission system operator (ČEPS), the incident was likely initiated by the fall of a phase conductor – the element that carries energy in an electrical circuit. According to the preliminary information, this failure led to an automatic disconnection of several transmission lines and an outage of a power plant. As a result, part of the transmission network went into island operation mode, disconnecting from the larger national system, which in turn rendered it inoperable. Approximately 1 500 MW of production and 2 700 MW of consumption were affected by this sequence of events.

ČEPS immediately activated the system restoration procedures. By 14:00 CEST, the transmission system substations supplying Prague were put back into operation. By 15:00 CEST, the operation of all remaining affected substations was also restored.

The restoration of electricity supply to all consumers was well coordinated between ČEPS and the distribution network operators.

The severity of this incident will be assessed based on the Incident Classification methodology (ICS).