What is the testing frequency of an engine driven generator?

Testing of engine-driven generators is governed byNFPA 110, not NFPA 72. NFPA 72 references this standard for standby power systems.

NFPA 110 (2022), Section 8.4.1:

“Diesel generator sets shall be exercised at least once weekly.”

This includes running the generator under load and verifying automatic start capability.

NFPA 72 (2022), Section 10.6.3.2:

Refers to NFPA 110 for testing of standby/emergency power systems.

Correct answer: A. Weekly

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