NFPA 110 Emergency Generator Compliance Guide: Complete Requirements for Facility Managers

Understanding NFPA 110 and Its Role in Emergency Power Compliance

NFPA 110, the Standard for Emergency and Standby Power Systems, is the National Fire Protection Association standard that governs the performance, installation, maintenance, operation, and testing of emergency power supply systems (EPSS). It covers the complete system from the emergency power source (usually an engine-driven generator) through the transfer switches, up to the load terminals of the transfer equipment. NFPA publishes a new edition every three years; the current edition is 2025, following the 2019 and 2022 editions.

For facility managers, building owners, and maintenance directors, NFPA 110 usually becomes mandatory because another code points to it. The International Building Code (Section 2702) requires emergency and standby power systems to be installed in accordance with NFPA 110 and NFPA 111. In healthcare, NFPA 99 names NFPA 110 as a mandatory reference, and CMS requires hospitals, critical access hospitals, and nursing homes to follow its inspection, testing, and maintenance requirements -- which is why Joint Commission and CMS surveyors check it. Authorities Having Jurisdiction (AHJs) enforce whichever edition their jurisdiction has adopted, and that edition may be several cycles old.

This guide breaks down the critical requirements of NFPA 110 so you can ensure your emergency power systems meet code and protect the occupants who depend on them. Section numbers below are given with the edition they come from, because numbering has shifted between editions.

Who Must Comply With NFPA 110

NFPA 110 applies wherever a building code, fire code, healthcare regulation, or AHJ requires an EPSS to be installed or maintained to it. The occupancy types most directly affected include:

• Healthcare facilities -- Hospitals, critical access hospitals, nursing homes, and other facilities where NFPA 99 or CMS rules require an essential electrical system
• High-rise buildings -- Buildings with an occupied floor more than 75 feet above the lowest level of fire department vehicle access, which the building code and NEC treat as needing emergency power for life safety systems
• Assembly occupancies -- Convention centers, arenas, theaters, and other venues where large crowds require illuminated egress pathways
• Data centers and mission-critical facilities -- Where the owner's design specifications or the AHJ call for NFPA 110 performance
• Educational institutions -- Schools and universities with emergency lighting, fire alarm, and communication system requirements
• Government and institutional buildings -- Correctional facilities, courthouses, and emergency operations centers

If your facility has an emergency generator connected to life safety or legally required standby loads, assume NFPA 110 applies and confirm the adopted edition with your AHJ.

EPSS Classification: Level 1 vs. Level 2

NFPA 110 classifies every EPSS three ways: by Class (the minimum time, in hours, the system is designed to run at rated load without refueling), by Type (the maximum time, in seconds, the load terminals of the transfer switch may be without acceptable power), and by Level (how critical the loads are). Level and Type are separate choices -- NFPA 110 does not tie a transfer time to a Level. NFPA 110 also does not say which applications are Level 1 or Level 2; that determination belongs to the AHJ and the codes that require the system.

Level 1 EPSS

Level 1 systems are installed where failure of the equipment to perform could result in loss of human life or serious injury. These systems carry the most stringent installation, maintenance, and testing requirements. Level 1 roughly corresponds to emergency systems under NEC Article 700.

Typical Level 1 applications (loads the NEC treats as emergency systems):

• Hospital life safety and critical branch circuits
• Exit signs and emergency egress lighting
• Fire detection and alarm systems
• Emergency voice and public safety communications
• Fire pumps and elevators where required by code

Key Level 1 points:

• Where the loads are NEC Article 700 emergency loads or healthcare essential electrical systems, the system must be Type 10: power restored within 10 seconds
• Class is set by the application, code, or user; NFPA 99 designates healthcare generators Class X, meaning the run time is set by the AHJ or the facility's own plan
• Weekly inspection and monthly exercise under load
• A 4-hour load test at least once every 36 months

Level 2 EPSS

Level 2 systems are installed where failure of the EPSS to perform is less critical to human life and safety. Level 2 roughly corresponds to legally required standby systems under NEC Article 701.

Typical Level 2 applications (loads the NEC treats as legally required standby):

• Heating and refrigeration systems where loss would create a hazard
• Communication systems
• Ventilation and smoke removal systems
• Sewage disposal
• Industrial processes that would create hazards or hamper rescue if interrupted

Key Level 2 points:

• NEC Article 701 loads must be restored within 60 seconds, so these systems are commonly Type 60
• Monthly exercise testing
• Somewhat less prescriptive maintenance (for example, Level 2 starting batteries are inspected monthly rather than weekly under the 2025 edition)

EPSS Classification Summary

Required Testing Intervals Under NFPA 110

Testing is the backbone of NFPA 110 compliance. The standard prescribes specific testing intervals and conditions to verify that the EPSS will perform when called upon during an actual outage. The section numbers below are from the 2010 edition, which is the edition CMS enforces for healthcare facilities through NFPA 99-2012; confirm the numbering in the edition your AHJ has adopted.

Weekly Inspection

The EPSS, including transfer switches, must be inspected weekly (Section 8.4.1). A weekly walk-around typically covers fuel level, coolant and oil levels, battery charger status, alarms, and general condition.

Monthly Exercise Testing

Diesel generator sets must be exercised under load at least monthly for a minimum of 30 minutes (Section 8.4.2), using one of the following loading conditions:

1. A load of not less than 30% of the nameplate kW rating, or
2. A load that maintains the minimum exhaust gas temperature recommended by the manufacturer

Healthcare facilities must run the monthly test 12 times a year at intervals of not less than 20 days and not more than 40 days. The cool-down period does not count toward the 30 minutes.

Annual Supplemental Load Test (When Monthly Loading Falls Short)

If a diesel unit's monthly tests do not reach 30% of nameplate or the manufacturer's exhaust temperature, it must still be exercised monthly with the available load, and once a year it must be run with supplemental load for 1.5 continuous hours: at least 30 minutes at 50% of nameplate, followed by at least 60 minutes at 75% of nameplate (Section 8.4.2.3). A portable load bank is the usual way to add that load. Chronic under-loading causes wet stacking, which this test is meant to burn off.

36-Month (Triennial) Load Test

Level 1 systems must be tested at least once every 36 months for a minimum of 4 continuous hours (Section 8.4.9), at not less than 30% of nameplate kW or the manufacturer's minimum exhaust gas temperature for diesel units. The annual supplemental test and the 36-month test may be combined: the first 3 hours at not less than 30% of nameplate (or the minimum exhaust temperature) and the final hour at not less than 75% of nameplate. See our 36-month 4-hour load test guide for planning details.

Complete Testing Schedule

Transfer Time Requirements

One of the most critical performance metrics for an EPSS is its Type -- the maximum time the load terminals of the transfer switch can be without acceptable power after the normal source fails.

Type 10 systems must restore power within 10 seconds. NEC Article 700 requires emergency power within 10 seconds, and NFPA 99 requires the same for healthcare essential electrical systems, which is why nearly all Level 1 generators are Type 10. The 10-second window includes the ATS detecting the failure, any start time delay, engine cranking, run-up to rated speed and voltage, and transfer switch operation. In healthcare, if the 10-second criterion is not met during the monthly test, CMS expects a process to confirm the capability annually for the life safety and critical branches.

Achieving this requirement depends on:

• Engine starting system reliability -- Starting batteries must be maintained and tested so they deliver cranking performance in all ambient conditions
• Engine heater operation -- NFPA 110 requires the unit to be heated as needed to keep the water jacket and battery at the temperature the manufacturer specifies for cold start and load acceptance
• ATS programming -- NFPA 110 requires a time delay on engine start to ride through momentary dips; its annex suggests a nominal 1 second is adequate for most applications, and all delays must fit within the Type 10 envelope
• Fuel system readiness -- Day tanks and fuel supply lines must be ready to deliver fuel immediately upon engine start

Type 60 systems (common for NEC Article 701 legally required standby loads) have 60 seconds, but the same principles of reliability and maintenance apply.

Documentation and Record-Keeping

NFPA 110 places significant emphasis on documentation. During an AHJ inspection or healthcare survey, your records are often the first thing reviewed, and incomplete records are a common finding.

What You Must Document

• Operational log -- Every start, whether test or emergency, with date, time, duration, and reason
• Test records -- Load level (kW), voltage, frequency, oil pressure, coolant temperature, and ambient conditions for every monthly, annual, and 36-month test
• Maintenance records -- All preventive and corrective maintenance activities with dates, technician identification, and parts replaced
• Fuel records -- Fuel deliveries, consumption tracking, and annual fuel quality test results
• Battery records -- Monthly test results; for maintainable (flooded) batteries, the 2025 edition requires a record of electrolyte specific gravity or an approved alternative test method
• Deficiency log -- Any issues found during testing or inspection, with corrective action taken and date of resolution
• ATS records -- Transfer and retransfer times, voltage sensing verification, and maintenance performed

Common NFPA 110 Violations Found During AHJ Inspections

Based on industry experience, the following problems come up repeatedly during AHJ and survey reviews of emergency power systems:

1. Incomplete or Missing Test Records

Facilities that run their generators monthly but fail to record load levels, operating parameters, and deficiencies are technically non-compliant regardless of how well the equipment performs. The Joint Commission has reported utility system testing among the most frequently cited physical environment issues in its recent hospital surveys.

2. Insufficient Loading During Monthly Tests

Running a diesel generator at no load or minimal load during monthly exercises fails the 30%-of-nameplate (or exhaust temperature) criterion of Section 8.4.2. If you cannot reach it with building load, the annual supplemental load test becomes mandatory.

3. Expired or Degraded Fuel

Diesel fuel degrades over time through oxidation, microbial contamination, and water accumulation. NFPA 110 requires tanks to be sized so fuel is used within its storage life (or stale fuel is remediated or replaced) and requires an annual fuel quality test.

4. Battery Failures

Starting batteries are a frequent cause of failure to start, which is why NFPA 110 requires regular battery inspection and monthly testing. Defective batteries must be replaced immediately upon discovery of defects.

5. ATS Maintenance Neglect

Automatic transfer switches with corroded contacts, failed voltage sensors, or uncalibrated time delays can prevent power transfer even when the generator starts and runs correctly. Transfer switches must be inspected weekly and operated monthly.

6. Blocked or Restricted Airflow

Generator rooms require adequate ventilation for combustion air intake and heat rejection. Facilities that use generator rooms for storage or allow debris to accumulate near intake and exhaust openings create both a code violation and a fire hazard. NFPA 110 does not permit the EPS room to be used for purposes unrelated to the EPS. See our guide to generator room design.

7. Fuel Storage Below Required Levels

The EPSS Class sets how long the system must run at rated load without refueling. Facilities that allow fuel levels to drop below that quantity are out of compliance even if the generator is otherwise fully functional. Level 1 systems must also alarm on low fuel in the main tank.

2025 Edition Updates and Key Changes

There is no 2024 edition of NFPA 110; the editions in current use are 2019, 2022, and 2025, with the next edition scheduled for 2028. Your AHJ may enforce an older edition, and CMS still enforces the 2010 edition for healthcare testing. Notable changes in the 2025 edition include:

Reliability-Centered Maintenance

The 2025 edition expressly permits reliability-centered maintenance (RCM), with new annex guidance on adopting an RCM program. The annex cautions that RCM must not undermine the standard's basic maintenance objective, so it is an alternative planning method, not a way to skip required tests.

Expanded Starting Battery Technologies

Earlier editions required nickel-cadmium or lead-acid starting batteries. The 2025 edition also permits nickel-zinc, lithium-ion, or other stored energy technologies capable of providing the required cranking cycles. Battery testing language was also expanded: batteries without electrolyte access are tested monthly by conductance, ohmic, carbon pile, or cranking voltage drop methods.

Level 1 Start Signal Monitoring

New for Level 1 systems, the integrity of the start signal circuit from a remote device such as an ATS or paralleling control must be monitored for broken, disconnected, or shorted wires, and a fault in that circuit must start the generator.

Main Fuel Tank Sizing

For systems classified at more than 24 hours, the 2025 edition requires the main fuel tank to hold at least 100 percent of the low-fuel sensor quantity; the 2022 edition required 133 percent. Systems classified at 24 hours or less still require at least 133 percent.

Building a Compliant Maintenance Program

Achieving and maintaining NFPA 110 compliance requires a structured, proactive approach to EPSS management. The following framework provides a starting point:

1. Identify your EPSS classification -- Confirm with your AHJ the Class, Type, and Level of your system and the NFPA 110 edition being enforced
2. Establish a written testing schedule -- Document weekly, monthly, annual, and 36-month testing dates for the year (see our weekly, monthly, and annual maintenance schedule)
3. Assign qualified personnel -- Designate individuals responsible for testing, maintenance, and record-keeping
4. Implement standardized test forms -- Use consistent documentation templates that capture all required data points, such as our printable NFPA 110 test log
5. Contract with qualified service providers -- Engage technicians trained by the manufacturer or holding a recognized industry credential
6. Schedule supplemental load bank testing -- Plan ahead if building loads cannot meet the monthly loading criterion
7. Maintain fuel quality -- Test fuel at least annually using appropriate ASTM standards (ASTM D975 is the specification for diesel fuel oils) or the manufacturer's recommendations
8. Review records quarterly -- Audit your own documentation before the AHJ does to catch and correct gaps

Conclusion

NFPA 110 exists to ensure that the emergency power systems protecting building occupants and critical operations will perform when they are needed most. Compliance is not simply a regulatory checkbox -- it is a commitment to the safety and continuity of the people and processes within your facility.

By understanding the classification of your EPSS, adhering to required testing intervals, maintaining thorough documentation, and addressing deficiencies promptly, you can build a compliance program that satisfies AHJ requirements and, more importantly, delivers reliable emergency power when it matters.

Review your current testing records, fuel management practices, and maintenance logs against the requirements outlined in this guide, and confirm which edition your AHJ enforces. If gaps exist, address them now -- not after an inspection finding or, worse, after a power failure exposes a deficiency that could have been prevented.

Sources and References

• NFPA 110: Standard for Emergency and Standby Power Systems (document information and edition history) -- National Fire Protection Association. https://www.nfpa.org/codes-and-standards/nfpa-110-standard-development/110
• NFPA 110 for Emergency Power Systems: 2025 Updates (PowerHour, August 21, 2025) -- Cummins Inc. https://www.cummins.com/sites/default/files/2026-04/2025-aug-nfpa-110-for-emergency-power-systems.pdf
• NFPA 110, 2025 Edition: summary of updates -- Fire-Police-EMS (NFPA distributor listing). https://www.fire-police-ems.com/NFPA110-2025.shtml
• Form CMS-2786R, Fire Safety Survey Report, 2012 Life Safety Code, Health Care (K918) -- Centers for Medicare and Medicaid Services. https://www.cms.gov/Medicare/CMS-Forms/CMS-Forms/downloads/cms2786R.pdf
• State Operations Manual Appendix Z, Emergency Preparedness (Tag E-0041) -- Centers for Medicare and Medicaid Services. https://www.cms.gov/Regulations-and-Guidance/Guidance/Manuals/downloads/som107ap_z_emergprep.pdf
• Life Safety Documentation Requirements Based on the 2012 Edition of NFPA 101 -- North Dakota Health and Human Services. https://www.hhs.nd.gov/sites/www/files/documents/DOH%20Legacy/LSC/lsc-documentation-requirements.pdf
• Emergency Generator Monthly Test - 30% Threshold (Standards FAQ, archived June 2025) -- The Joint Commission. https://web.archive.org/web/20250605202129/https://www.jointcommission.org/standards/standard-faqs/hospital-and-hospital-clinics/environment-of-care-ec/000001265/
• Emergency Generator 4-hour Load Test (Standards FAQ, archived June 2025) -- The Joint Commission. https://web.archive.org/web/20250620105716/https://www.jointcommission.org/standards/standard-faqs/hospital-and-hospital-clinics/environment-of-care-ec/000001267/
• Accreditation 360 - Updated Accreditation Manual: Physical Environment Chapter (webinar transcript, September 2025) -- The Joint Commission. https://digitalassets.jointcommission.org/api/public/content/e7ecc1b57fb14179b3e9a026d0a27a0e?v=bca59654
• NFPA 110 Levels 1 and 2 Standards for Generator Systems (Information Sheet 25) -- Clifford Power Systems. https://cliffordpower.com/wp-content/uploads/2024/02/IS_25_NFPA110_Level1_2-REV-11-1-19.pdf
• NFPA 110 Classification of EPSS -- Curtis Power Solutions. https://www.curtispowersolutions.com/nfpa-110-classification-of-epss
• NFPA 110 Installation and Environmental Considerations -- Curtis Power Solutions. https://www.curtispowersolutions.com/nfpa-110-installation
• Complying with Inspection, Testing and Maintenance for Electrical Systems -- Health Facilities Management (HFM) Magazine. https://www.hfmmagazine.com/articles/4461-complying-with-inspection-testing-and-maintenance-for-electrical-systems
• Implementing 2019 NFPA 110 -- Consulting-Specifying Engineer. https://www.csemag.com/implementing-2019-nfpa-110/
• IBC Section 2702 Emergency and Standby Power Systems -- Connecticut Department of Administrative Services. https://portal.ct.gov/-/media/DAS/OEDM/2015-CD-HO/ibc_section_2702_emergency_and_standby_power_systems.pdf?la=en
• Review of 2026 NEC Article 700 Emergency Systems -- ESL Power Systems. https://eslpwr.com/wp-content/PDF/Webinar%20-%202026%20NEC%20Article%20700%20(PDH).pdf
• Emergency and Standby Power for Commercial Occupancies -- IAEI Magazine. https://iaeimagazine.org/issue/july-august-2021/emergency-and-standby-power-for-commercial-occupancies/
• ASTM D975: Standard Specification for Diesel Fuel -- ASTM International. https://store.astm.org/d0975-26b.html