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Generator RepairStandby machines almost never fail from overwork. They fail from sitting still, and the failure is discovered at the worst possible moment.
A standby generator spends nearly all of its existence switched off, and that is precisely the condition that degrades it. Fuel deteriorates in storage and forms deposits that block small passages. Batteries self-discharge and sulphate. Seals dry out and leak. Rodents find a warm dry enclosure with convenient wiring to chew. Contacts oxidise. None of these processes require the machine to have ever run, and all of them are quietly under way during the years when the owner assumes nothing is happening.
The result is the characteristic standby failure: a unit that has been sitting reliably for years, has never given any trouble, and does not start on the one occasion it is needed. It did not break at that moment. It broke gradually while nobody was looking, and the outage merely revealed it.
Most standby units are configured to start themselves on a schedule and run briefly. That exercise cycle does real work: it circulates lubricant, charges the battery, keeps seals wetted and burns off some accumulated moisture. It is genuinely valuable and it is also frequently over-trusted.
An unloaded exercise cycle proves that the engine starts and runs. It proves nothing about whether the unit can carry the load it exists to carry, because running without load exercises neither the alternator under demand nor the control system's ability to transfer that load. It also proves nothing about run duration, since a five minute cycle cannot reveal a cooling or fuel supply problem that appears at forty minutes.
An owner who has watched the unit exercise weekly for six years has watched six years of evidence about starting and no evidence at all about performing. Those are different questions and the second is the one that matters during an actual interruption.
Load testing applies a genuine electrical demand to the unit and holds it there long enough for thermal conditions to stabilise. It is the only test that answers the question the machine exists to answer, and it routinely finds conditions that exercise cycles never surface: alternator output that sags under demand, cooling that is adequate briefly and inadequate sustained, fuel delivery that cannot maintain flow at full draw, and control or transfer equipment that fails to switch correctly when it actually matters.
Beyond load performance, a proper service covers the starting system as a whole. Batteries need testing under load rather than at rest, since a battery reading normal voltage can collapse the instant a starter engages. Stored fuel needs condition assessment, because degraded fuel is a leading cause of failure to start. Enclosures need inspection for rodent damage and moisture ingress. These are unglamorous items and they account for the majority of standby failures we are called to after an outage has already exposed them.
It proves the engine starts and runs, which is worth having. It proves nothing about whether the unit can carry load, sustain output over a long run, or transfer correctly. Those are different questions and they need load testing.
Because disuse is the degrading condition. Fuel deteriorates and forms deposits, batteries sulphate, seals dry and leak, contacts oxidise and rodents get into enclosures. None of it requires the machine to have run.
Applying a genuine electrical demand and holding it long enough for thermal conditions to stabilise. It surfaces alternator sag under demand, cooling adequate briefly but not sustained, fuel delivery that cannot maintain flow, and transfer equipment that fails when it matters.
The starting battery or the stored fuel, in that order. Batteries read normal voltage at rest and collapse when the starter engages, so they need testing under load. Degraded fuel is the other leading cause.
An exercise cycle answers the first. Only load testing answers the second. Call to have your standby unit tested against what it will actually be asked to do.