Generator - Monthly Load Test

What is the requirement for initiating and completing the monthly emergency generator load test?

Any examples are for illustrative purposes only.

The monthly emergency power system load test is to be initiated by a simulated or actual loss of normal electrical power.  

There are 2 methods both of which are acceptable means of initiating the monthly test:
  • A TEST Switch may be included on the automatic transfer switch (ATS) to simulate loss of normal power
  • Alternatively, a circuit breaker feeding an ATS is opened resulting in a loss of normal electrical power
In either case both will result in activating the starter for the generator and activation of the ATS transferring the load from normal power to emergency generator power.

The duration of the test is to be at least 30-continuous minutes with a minimum dynamic load of at least 30% of the nameplate rating.  The cooldown period for the generator is not included as part of the 30-minute run time.

The monthly test is invalid if the generator is started and allowed to run for a period before activating the ATS to transfer the load to the generator.  This does not fully test the generators ability to respond in actual emergency conditions, which require sensing loss of normal power and providing emergency power within 10 seconds from a cold start.

Additional Resources:
EC.02.05.07 EP 5 and EP 6
NFPA 99-2012: 6.4.4.1
Last updated on May 20, 2020
Manual: Critical Access Hospital
Chapter: Environment of Care EC

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