Students at Rangitoto College, on Auckland's North Shore, have been sent home for the afternoon after the school's transformer blew.
It is understood the cabling was not sufficient to carry the electrical load.
The fault has left the secondary school - New Zealand's largest - without power or a working sewage system.
Principal David Hodge said the school had to send all 3,000 students home early this afternoon because it was a health and safety emergency.
He said there were no working toilets at the college and it was unclear if the electrical fault would be fixed by tomorrow.
School staff would update parents via email and the school's website, he said.
- NEWSTALK ZB, NZHERALD STAFF
Electrical fault shuts Rangitoto College
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