Kimberley O'Sullivan, a researcher at the University of Otago's Department of Public Health says pre-pay consumers are more likely to be struggling than others, yet they're on a service that will cut out - much like a prepaid phone service.

There are gaps in the data too. More information is needed on both who is disconnected and for how long. O'Sullivan said the need for that information is urgent.

"It's potentially thousands of families siting at home disconnected and we don't know because we're not collecting that data and publishing them."

Research has found 50% of people on pre-pay plans had been disconnected in the past 12 months and of those, one third had been disconnected for at least 12 hours.

"These customers pay for power before they use it and often can't access discounts or varied pricing schemes," O'Sullivan said. 

More detail and the video