Eskom would implement stage one blackouts from 10am on Wednesday, it said.
“There is a high demand for power and Eskom cannot meet the demand,” said spokesman Khulu Phasiwe.
He said the risk of blackouts was high for the rest of the week.
Less power generation capacity and outages at several units has led to the implementation of the blackouts.
“At Majuba power station, unit three has an ash conveyer belt which is stuck, and at Duvha, unit 2 tripped last night due to a technical fault on the electrical side that is currently being repaired,” the power utility said in a statement.
Work continued at Koeberg which experienced a fault on Sunday.
On Monday, Eskom said the power grid was under pressure after one of Koeberg’s 900MW units was taken out of service because of a technical fault.
“The unit is expected to be at full capacity by the end of the week. The same unit is due for planned outage on 9 February 2015 and will be returned to service again in May.”
Johannesburg City Power spokesman Sol Masolo said Eskom alerted City Power just after 8am to implement the blackouts.
On Tuesday morning, Eskom said it would implement power cuts from 10am to 10pm.
Around 11am, it cancelled power cuts because there was a significant drop in electricity demand.
The power utility then reverted to stage one at around 5pm and said this was due to a constrained power system.
Stage one allows for up to 1GW of the national load to be cut, stage two for up to 2GW and stage three for up to 4GW. — Sapa
