ELECTRICITY SUPPLY — QUALITY OF SUPPLY
Please find attached the invitation for comment and the consultation document in respect of the NRS 048-9 Electricity Supply – Quality Of Supply: Code Of Practice in terms of the Electricity Regulation Act, 2006 (Act No. 4 Of 2006).
Final comments must be submitted by 18 March 2019, members are therefore requested to send preliminary comments by cob 28 February 2019 please.
South African Chamber of Commerce and Industry (SACCI)
Tel: +27 11 446 3800
Fax: 086 549 2662
SACCI New Office Address: 18 Hurlingham Road, Illovo
Correspondence to be directed to
The Technical Governance Manager
Private Bag X13
Halfway House 1685
Telephone : (011) 651 6830
Fax : (011) 651 6827
E-mail : email@example.com
Website : http://www.nrs.eskom.co.za
Emergency load reduction is a measure implemented by the System Operator and distribution
control rooms in order to prevent a national, regional or local blackout when system conditions are
such that demand cannot be met by the available power system capacity, or when adequate
reserves required to manage the power system security cannot be maintained without a reduction in
load. Emergency load reduction in this context refers to mandatory measures required over-andabove
contracted load reduction (demand response), energy conservation schemes, and demand
side management measures as may be in place at the time.
NOTE The power system includes generation, transmission and distribution infrastructure.
Emergency load reduction may take the form of load shedding (time-based interruption of supply to
customers on a rotational basis), mandatory load curtailment (self-reduction by customers in
response to an instruction given by the system operator), load limiting (a limit placed on the current
or power consumed by a customer, typically enabled by smart meter technology), or customer load
switching (remote switching of customer circuits to specific appliances, typically enabled by smart
meter technology or ripple control technology).
Load shedding differs from a blackout in that load shedding is a controlled intervention affecting a
limited number of customers at a time, whilst a blackout happens without warning in an uncontrolled
manner and can affect many (if not all) customers simultaneously for an unpredictable period of
NOTE The media may at times refer to load shedding as “rolling blackouts”. The term load shedding is an
internationally accepted engineering terminology for controlled load reduction by interrupting supply to
customers on a rotational basis.
Restoration of supply to all customers after a significant system incident or blackout could take days
to weeks. Whilst the order in which supply is restored to individual customers is often dictated by the
nature of the incident, the ability to restore supply to essential loads as quickly as possible should
form part of the restoration regime. This requires that essential load requirements are provided by
customers to power system operators.
This part of NRS 048 was developed to address the need for a national code of practice for real-time
emergency load reduction and restoration of supply after a major system incident. The code
addresses not only the power system requirement (the load reduction required) but how this is done
and communicated so as to have the least negative impact on critical infrastructure. This need for
such a code arose subsequent to national load shedding undertaken in South Africa in 2008.
Requirements for extreme power system constraints and blackout restoration have also been
included in the form of essential load requirements.