According to Eskom, load-shedding is “done countrywide as a controlled option to respond to unplanned events to protect the electricity power system from a total blackout.
Below is a detailed list and explanation of the load shedding schedules made available.
WHAT DOES STAGE 4 LOAD SHEDDING MEAN?
You will be scheduled for load shedding 12 times over a 4-day period for two hours at a time, or 12 times over an 8-day period for four hours at a time.
If more load needs to be shed than has been scheduled in Stages 1, 2, 3 and 4 then National Control will instruct additional, unscheduled load shedding. This means you may be shed outside of your scheduled times.
To prevent a nationwide blackout, Eskom needs to maintain the national power grid at the international standard of 50Hz, and when the grid is under pressure with normal measures implemented, Eskom must reduce demand, as agreed with the National Energy Regulator (Nersa).
Eskom then implements a process of load reduction which has two components:
Load Curtailment – The utility can instruct industrial clients to reduce electricity consumption when it is urgent to balance the system. This can reduce the load by up to 20%, significantly easing capacity on the grid but it can take up to two hours to implement.
Load Shedding – Load curtailment fails to ease the demand on the system, or there is not enough time to notify industrial clients of the need to reduce their consumption, Eskom implements load shedding to prevent an imbalance and subsequent blackout.
Load-shedding will be used under emergency conditions for limited periods.
Four schedules have been developed based on the possibility of risk and to ensure that load-shedding is applied in a fair and equitable manner:
- Stage 1 allows for up to 1000 MW of the national load to be shed.
- Stage 2 allows for up to 2000 MW of the national load to be shed.
- Stage 3 allows for up to 3000 MW of the national load to be shed.
- Stage 4 allows for up to 4000 MW of the national load to be shed.
Load-shedding will be implemented in most instances in 2-hour blocks.
- However, in Eskom-supplied Johannesburg areas, blocks are 4 hours long. This is to coincide with City Power’s 4-hour schedule.
Each of the time periods has an additional 30 minutes added to allow for switching of networks in a way that will not damage the power system.
- Most customers (those in 2-hour blocks) may, therefore, be without electricity for up to 2.5 hours at a time, while customers in 4-hour blocks may be without electricity for up to 4.5 hours at a time.