The National Fire Protection Association (NFPA) 110: Standard for Emergency and Standby Power Systems, provides specific requirements for acceptance testing of an emergency generator (one carrying National Electrical Code 700 loads). Over the years, these requirements have changed, so periodically reviewing the most recent version of the standard is recommended. The current version of NFPA 110 is 2013 with the next version scheduled for publication in 2016. Section 7.13 covers installation acceptance.
NFPA 110 attempts to ensure a high degree of reliability that the emergency backup power systems will perform as required. While compliance with this code is required for any emergency system application, the greatest attention to the NFPA 110 installation acceptance protocol is mostly seen in healthcare applications due to the addition oversight provided by the Joint Commission. The Joint Commission is an independent, not-for-profit organization that accredits and certifies more than 20,500 health care organizations and programs in the United States.
Installation Acceptance Procedure
For new, unoccupied buildings, the generator system is tested by opening all sources of normal power to the building. For occupied facilities, normal power failure can be simulated by operating the automatic transfer switches test function. The generator(s) need to be started from a cold start condition. This would be a generator with associated heaters enabled and at its normal non-running temperatures. The standard wants to verify that a cold generator will make normal start-up times and adequately pick-up and carry the facility load.
The generators are required to be tested with building load or other loads that simulate the intended building load for a period of 1.5 hours. For new construction with minimum to no facility load, this section has some ambiguity that may require local authority having jurisdiction (AHJ) clarification.
Section 220.127.116.11.3(2 ) requires no minimum loading; section 18.104.22.168.3(10) references adding other loads that simulate intended load; and the appendix 22.214.171.124 references test load being supplied through the load terminals of the transfer equipment. With new construction, we would interpret that this test could be performed with little or no facility load and no supplementary loading. But, AHJ interpretation of intent may be different.
The normal building load test requires the generator voltage, frequency, amperes, and startup time to be recorded. In addition, all of the switches transfer times need to be verified for compliance.
The building load testing is followed by a load bank test. This test requires 30% load for 30 minutes, 50% load for 30 minutes, and 100% load for the remaining 60 minutes. The load needs to be at rated power factor (typically 0.8 pf) unless the generator had a 0.8 pf load test at the factory.
Since resistive (1.0 pf) load banks are more common for field testing, most applications will choose to utilize factory reactive (0.8 pf) load testing. The duration of the 0.8 pf factory load test is not specified, but we would recommend performing a two hour factory load test to create alignment with in-field testing and minimize AHJ concerns. For applications with paralleled generators, the generators can be load tested individually. In previous versions of NFPA 110, this test was 100% load for the entire two hour period and it included a 100% load step requirement. Current versions no longer require the 100% load step.
In addition to load testing, the generators need to demonstrate sufficient battery capacity to meet the cranking requirements. The battery capacity is validated by disabling the generator, running through two complete crank cycles (total cranking time of 2 x 45 sec), and then starting the generator. All NFPA 110 defined protective functions must be validated per the manufacturers recommendations. This is typically accomplished by running the generator and then adjusting the control panel set points to trigger a warning or an alarm shutdown.
Through the NFPA 110 installation acceptance testing process, the generator is validated to ensure no oversights in the design, manufacture, installation, and application.
If you have questions about NFPA 110 code, contact your authorized Generac Industrial Power distributor or dealer.