The full load shedding programme (minus critical load) is now divided up into stages spanning from stage 1 to stage 16.
The National Energy Regulator of South Africa (Nersa) has published the NRS 048-9 Code of Practice Edition 3(Code) to govern how load shedding is implemented in South Africa.
The Code is primarily an electricity utility-driven and executed document that derives its mandate and authority, once approved by Nersa, as part of the Electricity Regulations Act.
The first edition of the Code was published in 2010, where load shedding stages were capped at Stage 4 (25% of the base load), requiring utilities to ‘find’ electricity under emergency conditions.
In 2019, the need for Stage 6 load shedding resulted in the second edition of the Code to extend the load shedding stages to manage load shedding to Stage 8.
In Stage 8, half the electricity load is shed and the other half is waiting to be shed.
This third edition introduces 16 stages of load shedding, giving more flexibility around load curtailment, and making provision for smart metering.
Eskom uses ‘load curtailment’ when large power users are directly asked to reduce their power usage. Companies are subjected to different stages of load curtailment, depending on the level of load shedding implemented. In contrast, load shedding is the rotational blackout of electricity supply which determines which areas are made powerless.
The new structure expresses load shedding as the percentage of demand assumed by the System Operator at the time the stage is called. The percentages range from 5% of demand at stage 1 to 80% at stage 16.
This offers more space for load shedding alternatives such as curtailment using load limiting relays, which will allow for schedules to be adjusted.