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Emergency Generator 4-hour Load Test

Can the generator load bank test be combined to meet the 36-month test as well as the 4-hour load test?

Any examples are for illustrative purposes only.

The testing for an annual load bank test and the triennial exercise may be combined according to NFPA 110-2010:
Summary of testing
Monthly load testing of at least 30% of the nameplate rating for 30 minutes for diesel powered emergency power supplies (EPS), see NFPA 110-2010:, EC.02.05.07 EP5 and EP6. The cool-down period (load disconnected) does not count as part of the 30 minutes test.

Annual load test (for situations not meeting monthly testing requirements) for diesel powered EPS
  • at least 50% of the nameplate rating for 30 minutes
  • at least 75% of the nameplate rating for 1 hour
  • Total test duration of not less than 1.5 continuous hours, see EC.02.05.07 EP6
Triennial or 36-month generator test 30% of nameplate rating for 4 continuous hours for diesel powered EPs, see EC.02.05.07 EP and EP10.

When combining both tests for diesel powered EPS, the first three hours of the test is required to be not less than 30% of the emergency generator nameplate kW rating or the minimum exhaust gas temperature. The last hour cannot be less than 75% of the emergency generator nameplate kW rating for a total of 4 continuous hours.

  • NFPA 110-2010 edition
  • EC.02.05.07
Manual: Ambulatory
Chapter: Environment of Care EC
Last reviewed by Standards Interpretation: June 01, 2022 Represents the most recent date that the FAQ was reviewed (e.g. annual review).
First published date: April 11, 2016 This Standards FAQ was first published on this date.
This page was last updated on June 19, 2023 with update notes of: Editorial changes only Types of changes and an explanation of change type: Editorial changes only: Format changes only. No changes to content. | Review only, FAQ is current: Periodic review completed, no changes to content. | Reflects new or updated requirements: Changes represent new or revised requirements.
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