It appeared he had attempted to cut the power cord to the caravan with pliers.
He was found around 3am by the occupants of the caravan, she said.
It was unclear how many volts the power cord carried, but it was thought to be around 240 volts.
His death has been referred to the coroner.
Campground owner Craig Stokes said he did not know the man who died.
"He'd been staying there a few nights with some mates. The police have got it all in hand." he said.
The camping ground offers motel units and cabins along with the campsite, with prices ranging from $130 per night for a motel room to $18 per adult per night for the camping ground.
The company's website said the harbour was a "haven for boating, fishing and water sports while the more adventurous can enjoy the open sea and waves of Oakura Beach".
A Worksafe New Zealand spokesman said it had been notified about the incident.