Equipment, known as the Firgrove 132kV feeder white phase current transformer, exploded.
Eskom said staff would be on site on Tuesday to assess the damage and do the necessary repairs.
Power was restored to central Stellenbosch and the surrounds in the early hours of Tuesday morning after a widespread electricity interruption on Monday night following a fire at the Devon Valley substation.
According to Eskom, the supply was interrupted at 21:50 following an explosion at the substation, affecting the municipality, Koelenhof, Cloetesville, Lynedoch, De Zalze, Kylemore and the neighbouring areas. The fire was caused by equipment which exploded, known as the Firgrove 132kV feeder white phase current transformer (CT),” the power utility said in a statement.