As thousands of datacentres are constructed across Europe, the Guardian and Investigate Europe have uncovered disturbing evidence that some workers building them are exposed to dangerous conditions and living in fear of speaking out

Sandu* checked his watch. He was winding down the last 15 minutes of his shift at a vast Google datacentre site in Saint-Ghislain, Belgium, in March, when the call came in. The 34-year-old electrical tester had already worked almost 10 hours, but says such last-minute jobs were normal: “I had no choice. People have been fired after saying no.”

The task was one Sandu had done many times before and involved a series of tests measuring the safety and integrity of the electrical wiring. A protective suit was locked away in an equipment room. The round trip would have added another 15 minutes to the job, he says, and people were waiting, so he decided not to retrieve the suit.