The Large Hadron Collider shut down at 1:23 a.m. (Geneva time) when a cable fault caused a failure in the 18-kilovolt power supply network. The network was back up by 10:30 a.m., according to CERN communicators.
The operations team at CERN is working on getting all parts of the LHC accelerator chain back up and running. Power cuts are a routine cause for down-time for particle accelerators, so the team was prepared for such a scenario.
A short circuit due to faulty insulation affected mainly the section of the CERN site in Meyrin, Switzerland, which houses the injectors and the main computing center but not LHC cryogenics. This means that the team does not need to undergo the lengthy process of cooling the magnets back to operating temperature before they can bring beam back to the machine.
Update 6:17 a.m. (Geneva time) December 3: Beam was back in the LHC at 10:15 p.m. last night. The operations team is back to testing and measuring beams at 450 GeV.