Load reduction hits Joburg to prevent 'total grid collapse'

After more than two months without load shedding and a mostly uninterrupted power supply across the country, Johannesburg electricity utility City Power is implementing “load reduction” in high-density areas to relieve the pressure on the grid.

In a move that is unlikely to surprise many sceptical Joburg residents, City Power has announced that it has been forced to implement “load reduction” and “load limiting” to prevent the power systems from collapsing.

“Electricity consumption in the City of Johannesburg has really reached critical levels, forcing City Power to embark on stringent measures to protect the grid from total collapse. These measures include the intensifying of the implementation of systems to basically ensure that we cut off electricity for geysers in homes where the system is under threat,” City Power spokesperson Isaac Mangena said on Monday, 10 June.

Mangena said the power utility was reducing loads in its substations, especially those under threat, and also stepping up the severing of illegal connections in informal settlements where electricity theft was common.

“City Power will be implementing load reduction from Monday, 10 June during peak periods from 4am to 10am, and also in the evening from 4pm to 10pm. These are high-density areas affected,” Mangena said. 

“The decision to initiate load-reduction follows intensive efforts to encourage customers to use electricity wisely and efficiently in recent weeks. 

“Despite the warning about the constraints on the electricity network in the city, residents have not reduced their electricity consumption and the demand has skyrocketed,” said Mangena. 

He said that in some areas, load limiting would also be implemented through smart meters to help customers save electricity without having to cut them off. 

“Both load shedding and load reduction can occur concurrently. In such cases, both Eskom and the municipality take responsibility and initiative to preserve the national and local systems, respectively,” said Bertha Dlamini, president of African Women in Energy and Power.

She said overloading the network can lead to transformer failures, explosions at substations and other infrastructure damages, potentially causing extended outages in suburbs, towns and regions.

“When the electricity distribution infrastructure is overloaded, it can result in costly damage, extended repair times and endanger the lives of workers and residents,” said Dlamini.

She said to prevent such issues, municipalities licensed to distribute electricity could apply load reduction.

“Load reduction targets specific areas and throttles the energy supply, ensuring each household still has electricity but with limited capacity,” she said. 

“This means high-energy appliances like geysers, air conditioners and others may not function. Households must learn to assess their load profile, understand the capacity their appliances consume, and use them wisely to preserve energy. This not only reduces their electricity bill but also helps the local municipal electricity network cope with demand, especially during peak periods,” said Dlamini. 

She said municipalities were required to communicate with residents about when and how load reduction would be applied, allowing them to prepare and turn off the appropriate appliances ahead of time.

Load reduction offers several benefits, according to Eskom: preventing extended and unplanned power outages; avoiding unnecessary costs, including reconnection fines; and ensuring the safety of people in an area.

In contrast, load shedding, typically implemented by Eskom, occurs when the entire system lacks sufficient capacity to meet demand. 

“Eskom determines the necessary stage of load shedding to preserve the national system and allow it to recover,” said Dlamini.

Mangena said the network was at critical levels due to the continuous demand, which was higher than the infrastructure could withstand. 

“As a result, we are implementing load reduction to areas where the load exceeds the maximum capacity demand.”

Mangena said that when load exceeded capacity demand, City Power was forced to pay penalties to the regulator, Nersa, and Eskom.

He said affected areas would be grouped into six blocks which would not exceed two-and-a-half hours per block.

City Power has published a schedule of when and where load reduction will be implemented.

City Power has over the months been monitoring its systems and recorded an enormous increase in the average evening peak load in some areas, escalating from 25MW during summer months to about 33MW between April and May this year.

According to City Power, in some instances, total demand has reached 42MW, a 110% increase in comparison with warmer seasons.

“During January and March this year, the average off-peak consumption at some of our substations has been sitting at about 20MW, and between April and May, consumption shot up by 50%, increasing the off-peak load to 30MW,” said Mangena. 

“The prudent use of energy is crucial to prevent overloading the local electricity network, which includes the distribution network and its equipment,” Dlamini said. 

She said City Power customers had not grasped the habit of switching off high power-consuming home appliances such as geysers in the morning and turning them back on at night. 

Dlamini said as the country moved into winter, the demand for electricity in the mornings and evenings was expected to skyrocket. 

“This increased demand will result from the higher usage of geysers, heaters, clothes dryers and air conditioners, significantly putting pressure on both the local and national electricity systems.”

Mangena said, “With temperatures expected to drop further between now, June and July, the consumption load will have dire consequences on our systems and infrastructure if load reduction is not implemented.” DM