Diesel generators are a decentralized way to generate power that relies on a localized store of fuel, rather than the flow of electricity from the municipal power grid. Because of this, they are a common choice for emergency electricity generation systems, or “backup generators.” It should come as no surprise that emergency electricity generation systems need to be inspected regularly, for two reasons: they are not otherwise in frequent use, which can lead to corrosion, deformation and other issues which plague machinery that is left idle for long periods; and secondly, they are intended for use during emergency situations when other power sources have failed, and therefore it is critical that they function correctly when called upon. NFPA is one of many regulatory agencies that has put out standards of maintenance for diesel generator inspections.

Diesel generator inspection requirements differ regionally and based on the application for which they are being used as an emergency power source. For example, those being kept on standby to power life support systems, such as generators at hospitals and nursing care facilities, must meet higher standards of testing regularity because of the assured loss of life that would result from a total power failure.

Guides such as the NFPA standards discuss not only testing regularity, but also “test conditions, personnel qualifications, maintenance and testing of circuitry, [and] maintenance of batteries.”¹ All parts of the generator power system need to be assured to be in good working order in the case of an emergency, and the person doing the testing must be correctly trained on how to administer it correctly.

Due to the emergency preparedness ingrained in the concept of a diesel backup generator, the protocols surrounding the generator’s use must also be robust to an emergency. For this reason, operating instructions are directed to be placed in two or more locations, at least one of which is extremely secure¹. As stated in “Inspection and Testing of Emergency Generators,” these manuals should contain repair instructions, maintenance instructions, and a labelled parts schematic of the system, among other sections. The emphasis on repair and user-friendly labelled diagrams in the manual highlights the idea that someone besides a trained technician may have to repair the system in an emergency situation. This stands in contrast to many equipment guides, which can be opaque and necessitate a trained technician even for simple fixes.

There are inspections recommended at various intervals, and they test different functions. For the most regulated backup generator systems, those in healthcare facilities, these tests can be as frequent as once a week. These weekly inspections comprise things like fuel levels, coolant levels, and electrical component status checks for parts like fuses and circuit breakers. Then, more intensive monthly tests can require running the system at full emergency load for 30 minutes or more. Because of the high liability involved with powering life-support equipment in the case of an emergency power outage, the testing procedures need to be conducted by a certified technician and rigorously documented in a maintenance log¹. Even for emergency diesel generators outside of a healthcare setting, the risk of electrical shock is high during testing so a skilled maintenance contractor is needed.