Substation failure triggers major blackout across Prague and northern Czechia

A major power outage struck much of Prague shortly after noon local time on 4 July 2025, affecting the city centre and districts including Sporilov and Jizni Mesto. Prague Energy (PRE) confirmed the cause was a failure at the CEPS substation in Chodov. Northern regions including Usti nad Labem, Teplice, Liberec and Jablonec were also affected, with tram services in Liberec halted. The grid operator CEPS reported a loss of voltage across parts of the national grid, and energy analysts noted a sudden 30 percent drop in grid load. In Prague, metro lines A, B and C and tram services stopped, mainly affecting the eastern, right-bank part of the city. Train services to nearby towns including Kolin, Benesov and Kutna Hora were disrupted, shops closed and ATMs went offline. Firefighters responded to numerous calls to free people trapped in lifts and reported smoke from buildings caused by emergency diesel generators. The underlying technical cause of the substation failure was not reported.

A failure at the CEPS substation in Chodov caused a loss of voltage across parts of the national grid, with a reported sudden 30 percent drop in grid load. The specific equipment fault was not reported.

1. A single substation failure can cascade rapidly into a wide-area outage affecting metro and tram transport, rail services, retail and cash machines across a large urban area.
2. Emergency diesel generators brought into service during an outage can create secondary hazards, in this case smoke inside buildings that drew a fire service response.
3. Lift entrapment is an immediate life-safety consequence of urban outages and needs agreed protocols between building operators and emergency services.
4. Transmission-level voltage monitoring helps operators establish the scale and origin of a voltage loss quickly and communicate it to distribution companies and the public.

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