Here is the problem nobody is talking about.
For the past 400 days, Eskom has been – against all expectations – largely functional. In June 2026, the grid recorded 406 consecutive days without load shedding. Generation availability is up. Diesel costs are down. Facilities Managers across the country have quietly moved backup power lower and lower on the priority list.
And that is precisely when standby systems fail.
Not during load shedding. Not during a crisis. During the long, quiet stretches when nobody is watching, and nobody is testing – because nothing has gone wrong recently, so why would it?
Here is the principle that should be printed on every generator room wall: The worst time to discover your backup doesn’t work is when you need it.
During Stage 6 load shedding, standby generators earned their keep. They ran regularly. Every start was an opportunity to catch faults – a battery with low cranking power, a fuel filter beginning to block, a coolant temperature running high. Regular use was, paradoxically, a form of maintenance.
Now many generators sit idle. Some for weeks. Some for months.
And they are deteriorating on schedule, whether they are running or not. Engines age. Rubber seals harden. Battery terminals corrode. Fuel systems accumulate contamination. Control electronics degrade. None of these processes paused because Eskom improved. None of them care what the grid is doing.
There is also a specific risk that catches generators out after extended idle periods: wet stacking. When a diesel generator runs repeatedly at low load or for short periods without reaching operating temperature, unburned fuel and carbon deposits accumulate in the exhaust system. The engine starts. The generator appears operational. And then it is asked to carry a real electrical load – and struggles.
So the monthly test that confirms the generator starts is not the same thing as knowing the generator works.
Diesel does not last indefinitely. Stored for extended periods without treatment, diesel is susceptible to water contamination, oxidation, and microbial growth – a genuinely unglamorous problem where bacteria colonise the fuel-water interface at the bottom of the tank and produce a sludge that blocks filters and damages injectors.
During load shedding, fuel turned over regularly. Tanks refilled frequently. The risk of fuel degradation was low simply because the fuel was being used.
With a stable grid, fuel can now sit in a standby generator tank for months. The tank may show full. The fuel may look clean. And the generator may still fail to support the load when it matters – not because the engine is faulty, but because the fuel system cannot deliver clean diesel at the required rate.
A backup power system is only as reliable as its weakest component. Fuel is a component.
Most generator maintenance programmes test whether the generator starts. Far fewer test whether the generator actually transfers the load correctly.
The Automatic Transfer Switch (ATS) or Automatic Mains Failure (AMF) system is the equipment responsible for detecting a utility failure and switching the facility from grid supply to generator supply. It includes controls, sensors, switching contacts and interlocks. It is not a passive device. It has moving parts, it has electronics, and it can fail.
A generator that starts perfectly and an ATS that fails means the critical loads are still without power.
The question a Facilities Manager should be asking is not “did the generator start?”
It is: “did the entire system transfer the correct loads, in the correct sequence, within the correct time-frame?”
Those are different questions. Most monthly tests only answer the first one.
Everything above applies equally to UPS systems – with one additional complication. When a power failure occurs, the UPS does not wait for the generator. It responds immediately, carrying the critical load on battery while the generator starts and the transfer sequence completes. The UPS is the bridge between the grid failing and the generator taking over.
If the UPS battery bank has deteriorated – if its actual autonomy has dropped from 60 minutes to 15 without anyone noticing – the generator does not need to be slow to start. It just needs to take longer than 15 minutes. Or it needs to start three times before it catches. Or the ATS needs a few extra seconds.
Battery deterioration is not announced. It does not trigger an alarm. A UPS battery bank can sit at significantly reduced capacity while the front panel shows green and every report says “completed.”
That is why UPS battery maintenance requires more than a visual inspection. Resistivity testing, float voltage measurement, and load verification give you actual evidence of battery condition – not just confirmation that someone attended.
Backup power is not a generator. It is a chain.
Utility → switchgear → ATS/AMF → generator → UPS → distribution → critical load
Every link has to work. And every link can fail independently of the others.
Before any of that matters, a Facilities Manager needs to know what the chain is actually protecting. Which circuits are genuinely critical? Which loads must remain operational? What is the expected backup duration? Which loads depend on the generator, and which depend on the UPS?
Without those answers, a facility may have backup equipment without having a backup strategy.
If your backup power system has operated less frequently in the past 400 days, these are the questions that deserve an answer – with records, not reassurance:
If any of those questions produce a vague answer, an approximate date, or a reference to a report that no longer exists – that is your answer.
South Africa’s improved electricity supply is genuinely good news. But your generator has not become more reliable because the grid has. Your UPS batteries have not maintained their capacity. Your ATS has not tested itself. Your fuel has not stayed fresh.
If anything, the stable grid has made it easier to overlook backup power maintenance – because the system is not being called upon regularly, and the absence of failures can feel like evidence of reliability.
It is not.
A standby system is not maintained by being needed. It is maintained so that it is ready when it is needed. The worst time to discover your backup power system does not work is not during load shedding. It is during the first significant outage after 400 days of stability – when the organisation assumed everything was fine because everything had been quiet.
Boron Facilities Management provides engineering-led preventative maintenance for generators, UPS systems, ATS/AMF controls, fuel systems, and critical electrical infrastructure across South Africa.
If your backup power system has seen less use over the past year, now is exactly the right time to review its condition – not when the next interruption arrives.