Millions of clocks have been lagging behind since mid-January in 25 European countries, from Spain to Turkey.

The reason? A power grid dispute between Serbia and Kosovo that caused a domino effect. So beyond bad weather in the region, slow alarms might be responsible for Polish, Dutch, Portuguese, and Danish workers being late to work and overcooking their food.

Electric clocks steered by the frequency of electricity through the power line, rather than by a quartz crystal, gradually lost time this year. Devices like plug-in clocks and microwaves may show a delay of nearly six minutes in most of the continent, according to the European Network of Transmission System Operators for Electricity (ENTSO-E), which represents European electricity transmission operators. The British Isles, Norway, Sweden, and most of the Eastern European countries have not been affected due to their lessened links to the continental grid.

What’s the Frequency?

The issue was caused by a frequency deviation in the electric system from the mean value of 50 Hz since mid-January 2018 (the standard is 60 Hz in America). Below 47.6 and above 52.4 Hz, all connected devices would automatically disconnect for safety reasons. But between that range, devices that measure time based on the power system run late when that frequency decreases, or run too fast when the system is in over-frequency. The average frequency of the affected system since mid-January 2018 has been around 49.996 Hz.

That deviation has now stopped, Serbian and Kosovar transmission system operators EMS and KOSTT confirmed to ENTSO-E. Of course, clocks can be manually set to the correct time; but for all devices to automatically go back to normal, the missing amount of energy during these last weeks would need to be compensated. The network has lost 113 gigawatt-hours (GWh) of energy since mid-January. That energy will be pumped back into the grid in a process that could take a few weeks.

“The return of the missing energy will be made so that the frequency will slightly increase. The over frequency will help catch up automatically the delay on clocks,” ENTSO-E spokeswoman Claire Camus told National Geographic. European operators still have to work out exactly who will be responsible for returning that energy.

A continuous frequency decline had never previously happened in the joint European grid, the Brussels-based organization said.

Political Roots

The initial cause of the discrepency has its roots in the longterm political conflict between Serbian and Kosovar authorities, grid officials say. The grid shared by Serbia and its former region is connected to Europe’s synched high-voltage power network. Yet the transmission system operator in Kosovo has been unable to buy enough supply to balance its network. According to the Continental Europe Operational Handbook, that should have been managed by their Serb counterpart, says Camus. “For political reasons, they did not,” she says.

Belgrade’s operator, EMS, blamed the problem on Kosovo, claiming that in January and February the region “was withdrawing, in an unauthorized manner, uncontracted electric energy from the continental Europe synchronous area,” The Guardian reports.

Principles of Power

Now that the frequency deviation has stopped, the next step is “to negotiate a political agreement with the European Commission and other authorities so that this situation never happens again,” Camus said. ENTSO-E and the EU executive branch are “fully mobilized to find a lasting solution,” she added.

Serbian forces were ousted from Kosovo in 1999, after U.S.-led NATO air strikes helped end Serbia's crackdown on ethnic Albanian separatists. Kosovo seceded from Serbia in 2008 and is now recognized by 112 of the 193 members of the United Nations.

The political dispute between the two countries that caused European clocks to run late is mainly about regulatory issues and grid operation, a Reuters report suggests. Serbia does not recognize Kosovo as an independent nation. Both countries signed an agreement on operating their power grid in 2015, but conflicting claims about ownership of the infrastructure make its implementation challenging.