He said there is a high probability of load shedding for Friday, but that it can only be confirmed after final planning.
"We are still in a serious situation. The outlook at this stage is not favourable," said Etzinger.
Eskom imposed rolling blackouts for the first time since 2008 on Thursday morning.
It said the grid had come under intense strain because of torrential rain in Mpumalanga, which had drenched coal supplies sitting outside power stations.
The South African weather service forecast thunderstorms over Mpumalanga until at least the middle of next week.
According to EWN, Eskom said that the electricity grid will remain vulnerable for at least about another two years.
It quoted Etzinger saying the two year period will be used to get generators back on stream and to bring capacity back.
The parastatal also came under fire from MP's in the National Assembly, reported Sapa. Opposition MPs used the podium to hit out at the ANC and Eskom for failing to ensure the country's two new power stations were built on time.
Public Enterprises Minister Malusi Gigaba told MPs that the staggered power cuts were likely to continue beyond Thursday.
"It is anticipated this emergency will continue until after the evening peak tonight, and we will continue to manage the system," he said.
Eskom confirmed to Fin24 on Thursday evening that it entered stage two of load shedding, meaning that there is a demand to save only 2 000 MW of electricity to prevent the national grid from total collapse.
During stages 1 and 2, power outages will take place from 06:00 to 22:00 from Monday to Saturday. Whereas stage 3 will see power cuts 24 hours a day throughout the week.
- Fin24, Reuters, Sapa, EWN