“We’ve always relied to some degree on the Victorian interconnector — that’s why it’s there, it’s been there for 25 years.
“Many times other supply will kick in and there’s always stuff on standby, but in this case it may well have been the size of the load.”
When the Victorian system shut down, 160 megawatts of energy was lost and wind power did not supply energy because it often does not start until 3am.
Mr Roberts said when outages were planned, people on life support were notified.
But last night’s blackout “caught everyone by surprise”, despite the fact Victoria had issued a low level risk notice for a power outage for the past seven weeks.
Mr Roberts said a review would be conducted into the widespread outage.