Standby generator maintenance that survives a real outage

A standby generator that starts on a no-load test every month is not proven. It has proved the battery and the starter. The failures that matter during a real outage are fuel, cooling and the transfer switch, and none of them are tested by a machine idling for ten minutes.

Weekly or monthly: the short check

• •Start and run, and record the actual run time rather than ticking a box
• •Coolant and oil levels, with the number written down
• •Battery voltage and charger status, which is the most common cause of a no-start
• •Fuel level and any water in the fuel filter or tank bottom
• •Block heater working, because a cold engine that will not take load is a failed start in practice

The battery is the answer most of the time

Across the industry, failed starts trace back to batteries more than to any other single cause. Test them properly rather than looking at them: a resting voltage tells you almost nothing about whether the battery will deliver cranking current in February.

Annually: the test that counts

Run the set under real load, through the transfer switch, for long enough to reach operating temperature. This is where the problems live.

• •Transfer switch operation, timed, in both directions
• •Load carried for at least an hour, with temperatures and pressures logged
• •Wet stacking checked on diesel sets that normally run unloaded, and a load bank test where it is present
• •Fuel sampled and tested, because stored diesel degrades and grows things
• •Exhaust, silencer and mounts inspected while hot

Fuel is the quiet failure

Diesel stored for a year is not the same fuel that went in. Water accumulates, microbial growth blocks filters, and the first sign is usually a set that runs for twenty minutes during an outage and then stops. Sample and test annually, and polish or replace the fuel on the interval your test results justify.

What the record needs to show

For an insurer, a regulator or a healthcare accreditation visit, the record has to show the date, the duration, whether load was carried, who did it and what was found. A tick in a box with a month next to it will not survive the question "show me the load test".

One thing to check today

Find out when the transfer switch was last operated under load. In a surprising number of buildings the generator is tested monthly and the switch that connects it to the building has not been exercised in years.