Five Victorians on life support weren't given notice about planned power outages to their homes, according to a report by the state's utilities regulator.
It also found Victorian energy companies were breaching industry rules an average of more than three times a day in the last six months of 2016.
The Victorian Essential Services Commission energy market report for July to December last year found five Victorians on life support weren't told about planned outages.
It also found 27 instances when a registered life support customer was improperly disconnected from electricity between July 2013 to September 2016.
The report said the mistakes occurred due to "human error or inaccurate maps", but luckily no-one was "materially affected".
Energy companies have since reported changes to ensure the errors don't happen again, including changes to systems, retraining staff and improving the accuracy of network maps.
The commission found energy retailers and distributors broke the rules 687 times in the six months to December 31 last year, including more than 370 wrongful disconnections that cost more than half a million dollars in payouts.
The problem appears to be getting worse, with energy companies on track to pass the previous financial year's figure of 565 wrongful disconnections.
During the 2015-16 financial year, Origin had 214 wrongful disconnections, AGL EnergyAustralia had 117, Lumo 63, Simply Energy 52, AGL 34 and Alinta 30,
A spokesman for the Australian Energy Council said rising electricity costs are placing increased pressure on customers and retailers alike.
"There were about 20,000 customers disconnected for not paying their bills and 379 disconnections were wrongful," the spokesman told AAP.
"While that is less than two per cent of all disconnections, it is still too many."
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