NFPA Generator Testing: A Basic Overview

To remain in good condition, your facility emergency power supply system (EPSS) requires regular maintenance and testing. Concerning the latter, the National Fire Protection Association (NFPA) has set guidelines for testing Level 1 and level 2 generators (a.k.a. gensets) on a monthly and yearly basis. Below is an outline of these guidelines according to NFPA 110:

Monthly Guidelines

Each month, a genset should be tested under available load for thirty minutes. During the procedure, the unit must do one of the following to perform at a minimum of thirty percent of its nameplate kilowatt rating, or achieve a minimum exhaust gas temperature as stated by the manufacturer. Most gensets pass the monthly test. Those that do not are subjected to an annual test as described below.

Annual Guidelines

Annual generator testing is recommended for gensets that fail the monthly test. Unlike the monthly procedure, the annual procedure is typically conducted using a supplied load from a load bank. In addition, the annual test lasts for a total of two hours. During this time, the genset must perform as follows:

  • 25 percent of the kilowatt rating for 30 minutes
  • 50 percent of the kilowatt rating for 30 minutes
  • 75 percent of the nameplate kilowatt rating for 60 minutes


The procedure above can help restore the efficiency of an old genset, preparing it to perform as expected during an outage. In some cases, the reason for inefficient performance is wet stacking a condition where unburned fuel accumulates in the exhaust mechanism of the genset. If left unresolved, wet stacking could cause equipment damage, along with a drop in efficiency.

Infrared Scanning

Infrared scanning is not a part of monthly or annual genset testing, but it should be performed annually to test for problems with EPSS components. Using an infrared scanner, a technician can scan EPSS components to identify potential problem areas. Often, these areas give off abnormal heat readings that are picked up by the scanner. In many cases, infrared scanning identifies problems in the early stages, before they show the usual signs.

Choosing a Provider

For facilities that contain Level 1 and Level 2 gensets, generator testing is an important aspect of protecting human life and business interests. Therefore, these facilities should have their EPSS maintained and tested by an experienced generator service in Georgia, such as Prime Power. When the procedures above are performed properly, a facility genset is prepared for a power outage.

For over twenty-five years, Prime Power has been the generator service in Georgia with the most expertise and broadest range of services. In addition to EPSS testing, we also supply industrial and commercial power users with the following services, among others:

  • Scheduled maintenance
  • Breaker testing
  • Healthcare utility management
  • Arc flash analysis and training
  • Modernization and retrofits


To have the genset in your facility tested according to NFPA guidelines, or to learn more about the services above, call Prime Power today for a free consultation.