A worker at Christchurch's Ravensdown fertiliser facility suffered an electric shock this morning.
St John Ambulance was called to the scene on Main South Rd, Hornby just after 9am.
Five other people were treated for injuries at the scene.
A Ravensdown spokesman confirmed the contractor had been working on a circuit breaker when the incident occurred.
He said Ravensdown staff assisted the man and he was taken to hospital via an ambulance.
Five others were also taken to hospital for a precautionary smoke inhalation check and were discharged.
The contractor remained in hospital. Ravensdown chief executive Gareth Richards said the man was an "integral part" of the company. He had worked for the company for a long time and he was "highly regarded by all who work with him".
"We take health and safety seriously and we're all gutted that something like this has happened. We're committed to providing a safe workplace for staff and contractors."
He said WorkSafe was advised and the company would work together to "undertake an investigation into what's happened and the lessons that can be learned".
"Our priority continues to be ensuring our people are cared for and our concerns and thoughts are with the affected person, his family and workmates," he said.
Ravensdown, a farmer owned fertiliser and soil management co-operative, confirmed the incident with a contractor happened at about 9.30am.
The contractor was undertaking maintenance on circuit breakers at the plant when he was shocked, the company said in a statement.
"An ambulance was called and Worksafe have been advised. Ravensdown staff assisted and the contractor has been taken to hospital," the statement said.
A Ravensdown spokesman could not confirm what caused the man to suffer an electric shock.
An Orion lines company spokesperson has confirmed that a power outage in the Hornby and Stockburn area of Christchurch this morning was "triggered" by the electrical incident.
The spokesperson said electricity went off unexpectedly at 9.19am as a result of the incident at the fertiliser plant.
It cut the supply of power to 268 customers and Orion had the service restored by 10.22am.
WorkSafe New Zealand said it was in the early stages of determining whether to investigate the incident.