This page explains what heavy outage seasons do to a generator and how a service programme should respond, from our teams in Johannesburg and Cape Town.
From standby to cyclic duty
A standby set is rated and maintained on the assumption that it runs rarely. Under scheduled outages it becomes a cyclic machine: frequent starts, runs of a few hours, then shutdown, repeated day after day. Hours climb quickly, and so does the number of starts, which matter just as much for batteries, starters and the engine.
Check whether your set’s rating suits the hours it now runs. If it is running for long periods most days, it may need treating as a prime-power set for service intervals and loading.
What frequent outages wear out
| Component | Why it suffers | Service response |
|---|---|---|
| Batteries and chargers | Many starts with short recharge time | Test capacity regularly; replace on condition, not age |
| Starter motor | Start count rises sharply | Inspect at shorter intervals; keep a spare for critical sets |
| Engine oil and filters | Hours accumulate fast | Move to hours-based drains and filter changes |
| Cooling system | Repeated heat cycles, summer heat | Clean radiators, check coolant, belts and hoses |
| Fuel system | High throughput, more deliveries, more water risk | Drain separators, change filters, test stored fuel |
| Transfer switch | Operates at every outage and restoration | Inspect contacts and mechanism; check timers |
Light load is the hidden risk
Many sites oversized their generators for comfort, or now run them only for essential circuits during outages. A diesel engine that runs at light load for many hours builds up carbon and unburned fuel in the exhaust, a problem known as wet stacking. The fix is to load the set properly, either by connecting more load or with periodic load bank runs, and to service the air and fuel systems. Our generator service kit page lists the parts we carry for these visits.
Fuel planning for long outage runs
Higher running hours mean more fuel deliveries and a bigger budget. They also mean fuel sits in the tank for less time in busy seasons and for longer in quiet ones. Keep the tank topped up before forecast stages rise, check for water after each delivery, and test stored diesel during long quiet spells. Our page on fuel quality management covers the testing side.
Log fuel used against hours run. A sudden rise can show a fault, a leak or a problem with deliveries.
A service calendar for heavy outage seasons
- Before the season: full service, battery capacity test, load bank run, ATS inspection and a fuel test.
- During heavy stages: weekly visual checks, monthly hours-based service where hours justify it, and immediate attention to any alarm.
- After the season: inspect starters and batteries, review fuel and hours logs, and plan any overhaul work while demand is low.
For what a standard visit includes, see our generator service in Johannesburg page.
Service records that pay for themselves
Heavy outage seasons generate a lot of information: how often the set started, how long it ran, how much fuel it used and what failed. Recording it properly turns a stressful period into data for better decisions. A simple log per generator, kept by the site and checked at each service visit, should show starts, hours, fuel deliveries and use, alarms and any work done.
From that log the service team can set hours-based intervals, see whether batteries and starters are ageing faster than expected, and spot fuel use that does not match running hours. Insurers and auditors increasingly ask for this kind of evidence after an incident, and it supports a case for replacing or upgrading a set when the time comes.
Our technicians use the same records to plan each visit, so the right parts and the right people arrive the first time.
When the generator is no longer the right answer
For some sites, years of load shedding have shown that a diesel standby set is not the cheapest way to stay powered. Solar with batteries can cover shorter outages and daytime load, with the generator as backup. Larger industrial users may look at on-site gas or a hybrid plant. Our engineers can compare the options using your actual outage and fuel records, and our hybrid power systems page explains the approach.
USP&E service teams in South Africa
Our South African service teams work from Johannesburg (22 Kildoon Rd, Bryanston) and Cape Town (31 Brickfield Road, Woodstock), covering commercial, industrial and mining sites. They are part of USP&E, a power EPC and O&M company with 150+ power projects in 45+ countries and 25,000 MW contracted since 2002.
Offices: Colorado Springs (1755 Telstar Dr, Suite 300), Knoxville (800 S Gay St, Suite 700), London (162-168 Regent Street), Johannesburg (22 Kildoon Rd, Bryanston), Cape Town (31 Brickfield Road, Woodstock) and China (No. 1 Ningzhou Road, Wuxi). Regions: USA | AFRICA | UK | UAE | CHINA. ISO 9001 and ISO 45001 certified.
Load shedding generator service FAQs
How often should a generator be serviced during load shedding?
On running hours rather than the calendar. Heavy outage stages can add hours quickly, so many sites move to hours-based oil and filter changes plus weekly checks.
Why do generator batteries fail during load shedding?
Frequent starts with short recharge time between outages wear batteries and strain chargers. Regular capacity tests catch weak batteries before they fail a start.
Is it bad to run a generator at light load?
Long periods at light load can cause wet stacking in diesel engines. Load the set properly or schedule load bank runs to keep it healthy.
Should my standby generator be treated as prime power?
If it now runs for long periods most days, its rating and service intervals should be reviewed with prime-power duty in mind.
Does USP&E service generators outside Johannesburg?
Yes. We work from Johannesburg and Cape Town and support sites across South Africa and the wider region.
Book a pre-season service
Ask us for a pre-season service, a battery and load bank test or a review of your outage and fuel records, and we will tell you what your generator needs.
Use the South Africa service team to send us your details, or speak to us directly on +27 10 822 2324 (info@uspeglobal.com). Need a larger or second set? See our diesel generator inventory.