A Chinese headmaster (Lei Hua) has been fired after a secret stack of cryptocurrency mining machines was found connected to his school’s electricity supply.
Teachers at the school in Hunan became suspicious of a whirring noise that continued day and night, local media report.
This led to the discovery of the GPU rigs, which were mining the cryptocurrency Ethereum.
The GPU rigs racked up an electricity bill of 14,700 yuan (£1,600).
The excessive electricity consumption had previously been reported to the headmaster, Lei Hua, but he reportedly dismissed it as being caused by air conditioners and heating devices.
The headmaster had originally spent 10,000 yuan on a single machine for use at home but allegedly decided to move it to the school after he saw how much electricity it consumed.
He used the school’s computer lab to install seven more mining computers between summer 2017 and summer 2018.
The deputy headmaster also became involved in the scheme and allegedly acquired a ninth machine for himself in January, which was also installed at the school.
The computer network in the building became overloaded as a result of the mining activity, according to reports, and this “interfered” with teaching.
The headmaster was fired in October and his deputy received an official warning.
A local authority responsible for “discipline inspection” has claimed the money that was made through the mining activities.
“The noise and heat of nine actively running mining machines would have been very noticeable,” said Matthew Hickey, a cyber-security expert at Hacker House.
“Sadly, stealing electricity is one way that people have tried to maximise their revenue — by avoiding those costs it can drastically improve returns on a mining operation.”