Large Hadron Collider out of action after tiny weasel bit into cable

A tiny weasel got into the circuitry of CERN’s Large Hadron Collider (LHC) in Switzerland, causing a short circuit and putting the world’s largest machine out of action. The LHC is offline and will be for the next few days, CERN announced.

Unfortunately, the weasel, which is a close relative of the polecat, stoat, ferret and mink, did not survive the encounter – it was electrocuted while in the transformer at the site near Geneva in Switzerland, and died.

The weasel had been chewing on a power cable in the 66 kilovolt transformer.

Weasel makes Large Hadron Collider stop workingOne of CERN’s internal documents placed online, informing of an ‘electrical perturbation’. (Image:

According to CERN, the LHC was operating when a ‘severe electrical perturbation’ occurred early on Friday morning.

CERN spokesperson Arnaud Marsollier announced:

“I can confirm that we had some issues overnight with electrical trouble. We suspect it might be due to a small animal.”

In an interview with the BBC, Mr. Marsollier said that having an animal affect CERN equipment is not a common occurrence. However, scientists were not surprised that a weasel got into the system, given that the LHC is in the middle of the Swiss countryside.

Technicians say it will probably be a few days before the LHC is back online. The equipment has not been affected and the problem should be easily fixed, Mr. Marsollier added.

Weasel identified as cause of short circuit at LHC‘Fouine’ is French for ‘weasel’. (Image:

This is not the first time an animal has caused power to shut down at CERN. In 2009, a bird was rumoured to have dropped a piece of baguette into a substation, resulting in a power cut.

While that power cut did occur, Mr. Marsollier said, the part about the bird and the French bread was a ‘tall tale’.

Mr. Marsollier said “This was a story that was told, but we never knew exactly what happened.”

Before the weasel incident shut everything down, the LHC was gearing up to begin colliding beams of protons again after a switch-off during the winter.

Mr. Marsollier said:

“We had collisions at low intensity recently, this is all part of the commissioning, we check that everything is working well, that the detectors are ready.”

About weasels in the UK

According to The Mammal Society, weasels (Mustela nivalis) are common across Britain. They are our smallest and probably most numerous carnivores. However, none have been observed in Ireland and most off-shore islands.

Weasels are found in a wide variety of habitats, including lowland pasture, woodland, marshes, moors and urban areas.

They are less common where their prey – small rodents – are scarce. They may also eat birds, young rabbits and eggs.

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