Record electricity use in the top of the South Island was blamed for lukewarm showers in Nelson on Monday.
Network Tasman chief executive Wayne Mackey said the exceptionally cold weather forced the company to cut hot water to users more than it usually would.
It was also the first day of the
school holidays, and the load on transmission lines feeding electricity into the Nelson region almost reached peak capacity.
Mr Mackey said the company used a "ripple control" system, turning hot water on and off in houses, like a relay, every day during winter.
The system was usually operated a few hours each morning and evening but on Monday it was used for much of the day.
"So people with small cylinders, very low storage temperatures, or old cylinders without good insulation, may have had only warm water rather than hot."
Such an event was very infrequent, he said.
"It might happen once a winter but it depends on how cold it is."
- NZPA
