Eskom puts a number on the capacity sitting above demand, and on how little diesel it is burning.

For a mine or smelter weighing whether it can contract for more power, the utility has now published the size of the cushion: roughly 6 855MW of generation available above what demand requires, with the evening peak put at 22 353MW against 25 278MW on hand before gas is counted.

The figures come from Eskom's weekly system update, issued on 6 November 2026. Availability for the financial year to 5 November stood at 68.16% on the energy availability factor, the share of fleet capacity actually fit to generate, up from 63.21% a year earlier, with about 6 481MW returned to the grid against the position three years ago.

Breakdowns have eased across the year, with 18.93% of capacity lost to unplanned outages so far, an improvement of 6.05% year on year. The week itself ran against that trend, at 18.41% compared with 16.82% in the same week last year, a reminder that grid reliability is read over months rather than days.

Diesel tells the same story. No open-cycle turbines ran for electricity in the week reported, and spend for the year to date was R1.26 billion, R4.81 billion below the R6.073 billion of a year earlier, with the turbines' load factor at 0.92% against 5.75%. The country has gone 539 days in a row without load shedding, counted from 16 May 2025.

Load reduction, the targeted curtailment used where illegal connections overload local networks, now reaches 102 551 customers, down from about 1.69 million, with roughly 1 591 837 customers returned to normal supply and seven of the nine provinces clear. Eskom says it intends to end the practice by March 2027. Read together, these numbers describe a reserve margin wide enough to take on new industrial load rather than ration existing load, which is a different matter from firmness at any single point on the transmission network.

For large power users, national headroom is not the same as headroom at your own supply point, and the two are decided by different parts of the utility. It is worth asking what the published surplus means for a capacity increase at your substation, and whether the availability you are exposed to on winter evenings matches the annual average.