NFPA 110 Generator Maintenance Requirements

Section 8.4 of NFPA 110, "Operational Inspection and Testing," is among the most frequently read, misquoted, misunderstood, and misinterpreted. This confusion often arises from taking material out of context. Examining this section in its entirety offers clear and straightforward guidelines for inspecting and testing the entire Emergency Power Supply System (EPSS). Clarity diminishes when the Authority Having Jurisdiction (AHJ) utilizes a part of 8.4 or adds its interpretation.

*NFPA 110, 8.4.1: EPSs, including all appurtenant components, shall be inspected weekly, and the EPSS shall be exercised under load at least monthly.

NFPA 110, A.8.4.1: Weekly inspection does not require running of the EPS. Running unloaded generators as part of this weekly inspection can result in long-term problems such as wet stacking. See Figure A.‍8.4.1(a) and Figure A.‍8.4.1(b).

*Source: NFPA 110, 2022 Edition – National Fire Protection Association (www.nfpa.org/110)

Incorporating Safety into Routine

There are nine (9) steps you must follow before, during, and after the weekly inspection:

1. Inform all affected personnel when the inspection will take place and its duration.
2. Collect all testing equipment, including, but not limited to, a hydrometer, fuel measuring stick, water-indicating paste, voltmeter, flashlight, rags, ladder, and recording log.
3. Don all appropriate safety gear.
4. Follow the specific lockout program designed for the EPSS being inspected. Before any employee performs any servicing or maintenance on a machine or equipment where the unexpected energizing, start-up, or release of stored energy could occur or cause injury, the machine or equipment must be isolated and rendered inoperative.
5. Inspect all EPSS systems according to the manufacturer’s recommendations and log information on a weekly inspection checklist. Always fill in the date, time, and EPS engine hours.
6. Inform all affected personnel that the EPSS is being restored to service.
7. Remove all lockout devices, close all circuit breakers, and restore the EPSS to automatic.
8. Replace all safety gear in the appropriate storage containers.
9. Complete the balance of entries on the checklist and submit it to the appropriate administrator.

Temporary Source of Power

During the inspection, the EPSS will not be able to supply the facility’s emergency system circuits with an alternate power source within the time prescribed by the Authority Having Jurisdiction (AHJ).

NFPA 110, 8.1.2 Consideration shall be given to temporarily providing a portable or alternate source whenever the emergency generator is out of service and the criteria set forth in Section 4.3 cannot be met.

While providing an alternate source does not present a problem for facilities with generator sets in a parallel configuration, those without this setup are put in a tenuous situation when performing weekly inspection tests with the EPS locked out or when the oil and filters are being replaced, and the EPS is out of commission.

General Condition of the EPS

Nothing that is not part of the EPS room should remain in the EPS room. Loose materials could end up in the radiator or alternator cooling ducts. Good housekeeping is essential.

NFPA 110, 7.11.1 The room in which the EPS equipment is located shall not be used for other purposes that are not directly related to the EPS. Parts, tools, and manuals for routine maintenance and repair shall be permitted to be stored in the EPS room.

Housekeeping is essential for units located outside in weatherproof housing. They are vulnerable to damage because they are situated outside a controlled environment. Ensure that access to the EPS room or housing is limited to authorized personnel only.

Verify that all transfer switches are locked and that the lights indicating normal power availability are illuminated. (The indicator lights showing alternate power availability have not been checked since the EPS is not operational. They will be inspected during the monthly load test.) Replace lamps as needed.

Conclusion

Proper maintenance and inspection of an Emergency Power Supply System (EPSS) are critical to ensuring its reliability during an emergency. NFPA 110 provides clear guidelines for operational inspections and testing. Yet, misunderstandings and misinterpretations often arise when sections are taken out of context or when the AHJ imposes additional requirements.

Facility managers can ensure compliance while maintaining system integrity by adhering to NFPA 110’s prescribed weekly inspections and monthly load testing. Thorough safety procedures, proper housekeeping, and regular equipment checks minimize system failure risks and extend the generator's and its components' lifespan.

One of the most important considerations during maintenance activities is the temporary loss of emergency power availability. Facilities without redundant power sources must develop contingency plans to mitigate potential risks when the EPSS is out of service. Following NFPA 110’s recommendation to provide an alternate power source when necessary helps maintain compliance and patient safety.

Effective generator maintenance is more than a regulatory requirement—it is a proactive measure that ensures the EPSS will perform as intended. By implementing best practices and adhering to NFPA guidelines, healthcare facilities, and other critical infrastructure can maintain operational readiness and protect the lives of those who depend on uninterrupted emergency power.