Power solution for Njala substation’s strained demand
The overload on the network on Njala is exacerbated by illegal connections downstream from substations, resulting in low-voltage supply, according to the metro.
To manage the growing electricity demand on the troubled Njala infeed substation, the metro has invested in the installation of the largest power transformer to be operational from December 2025.
The transformers will be installed on the new Wildebees infeed substation to increase its 250MVA capacity to relieve and support the Njala substation which supplies bulk electricity to substations in Pretoria east.
The Njala infeed station has suffered vandalism, cable theft and fire damage and was overloaded resulting in prolonged power outages.
The overloading of the network was exacerbated by illegal connections downstream of the substation, according to the metro.
“This substation is an infeed facility that supplies Hatherley, Koedoespoort, Mamelodi 1, 2 and 3, Mooikloof, Wapadrand and Waltloo 1 substations.
The metro said the city accompanied by the police regularly conducts removal operations, and the extent and scope of illegal connections are simply too great to address effectively.”
Two weeks ago, large parts of Pretoria east suffered a power outage following an explosion and fire at the Njala substation near Delmas Road.
According to the metro, the explosion heard by many residents that morning was one of the transformers catching alight.
The metro said a 275kV transformer exploded and was on fire on August 17 causing a widespread outage.
Metro spokesperson Lindela Mashigo said the station, which supplies predominately the east, has a capacity of 750MVA, while Wildebees will have a capacity of 250MVA.
This equates to 33% of the current load requirement.
“The capacity of Njala is 1 000MVA in total however with the transformer that burned, currently Njala is sitting on 750MVA, while the current demand is 554MVA. Another 200MVA was temporarily moved to another supplying station until the repairs are completed.”
Mashigo said the cause of the recent fire at Njala is yet to be determined.
“A new transformer will be purchased to replace the damaged transformer. The incident is still under investigation; it is not known if it was caused by growing electricity demand.”
Mashigo said the infeed Wildebees is expected to be completed by December 2027.
“Plans for additional capacity onto the system are underway. This will ultimately assist in addressing load demand requirements in the east.”
Mashigo said Wildebees will directly get electricity from Eskom and will relieve the load on the current system.
“The system operators will make informed decisions to balance the load at the various infeed points.”
He said an Environmental Impact Assessment for the construction of Wildebees has been approved.
“The community will not be inconvenienced (in respect of outages due to the project) while construction is underway.”
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