TL;DR
NFPA 110 governs emergency power systems for hospitals, data centers, and critical facilities. Hospital systems are usually Type 10 (power restored within 10 seconds), Class X (run time set by the AHJ) and Level 1. Key requirements: weekly inspections, a monthly exercise of at least 30 minutes at 30% or more of nameplate (or the manufacturer minimum exhaust temperature), an annual fuel quality test, and, for Level 1, a test every 36 months for the Class duration or 4 hours (whichever is less) at 30% or more of nameplate.
Reviewed by the FuelCare compliance team · Last reviewed October 2026 · BackupPower.ai is published by FuelCare, Inc., Seattle, WA
NFPA 110, Standard for Emergency and Standby Power Systems, is the technical backbone of backup power compliance in the United States. It defines how emergency power systems must be designed, installed, tested, and maintained — and it’s the standard that CMS, the Joint Commission, and most state regulators reference when evaluating generator compliance.
If you’re responsible for emergency generators at a healthcare facility, data center, or any building with life safety power requirements, understanding NFPA 110 is essential. This guide covers everything you need to know in plain English.
What Is NFPA 110?
NFPA 110 is a standard published by the National Fire Protection Association that establishes minimum requirements for the performance, maintenance, operation, and testing of emergency and standby power systems. The standard covers the entire system — not just the generator, but also the fuel supply, transfer switches, distribution equipment, and controls.
The current edition is NFPA 110-2025. CMS and the Joint Commission enforce the 2010 edition for health care, and other jurisdictions may enforce different editions. The standard is updated on a 3-year revision cycle.
NFPA 110 is not a law by itself, but it becomes legally enforceable when adopted by reference in building codes, state health codes, or federal regulations. CMS references NFPA 110 as part of the Conditions of Participation for Medicare/Medicaid providers, making it effectively mandatory for healthcare facilities.
Level 1 vs. Level 2 Classifications
NFPA 110 classifies emergency power systems into two levels based on the criticality of the loads they serve:
Level 1: Life Safety and Critical Operations
Level 1 systems support loads where failure could result in loss of human life or serious injuries. Most healthcare facilities require Level 1 classification for their emergency power systems.
Level 1 requirements include:
- Restoration time is set by Type, not Level; hospital Level 1 systems are usually Type 10 (10 seconds)
- System must be capable of running for the duration specified by the Class classification (see below)
- Highest standards for reliability, testing, and maintenance
- Fuel-capacity margin per Section 5.5.3, depending on edition and Class (confirm with your AHJ)
- Monthly exercise under load (this applies to Level 1 and Level 2 systems)
- Written operating and maintenance manuals
- Detailed record-keeping requirements
Level 2: Less Critical Operations
Level 2 systems serve loads where failure is less critical — typically standby systems for building services, data processing, or industrial processes where interruption causes economic loss but not immediate danger to life.
Level 2 requirements are less stringent than Level 1 but still include regular testing, maintenance, and documentation.
Type and Class Classifications
Beyond Level, NFPA 110 uses Type and Class to further define system requirements:
Type: Maximum Time to Restore Power
Type specifies the maximum time, in seconds, the system may take to restore power after a utility failure (NFPA 110 Table 4.1(b)):
- Type U: 0 seconds (basic uninterruptible, such as a UPS)
- Type 10: 10 seconds
- Type 60: 60 seconds
- Type 120: 120 seconds
- Type M: manual, no time limit
Hospital essential electrical systems are usually Type 10: the generator must start and the transfer switches must transfer the load within 10 seconds of a utility failure. NFPA 110 has no 96-hour Type, and CMS does not set a Type or Class.
Class: Minimum Run Time
Class defines how many hours the system must be able to run at its rated load without refuelling (NFPA 110 Table 4.1(a)):
- Class 0.083: 0.083 hours (5 minutes)
- Class 0.25: 0.25 hours (15 minutes)
- Class 2: 2 hours
- Class 6: 6 hours
- Class 48: 48 hours
- Class X: other duration, set by the AHJ, the governing code or the facility’s plan
Hospitals are usually Class X, with the run time set by the AHJ or the facility’s plan. NFPA 110 has no 96-hour Class and no Class 0.167. A typical hospital system is Type 10, Class X, Level 1.
Chapter 7: Installation Requirements
NFPA 110 Chapter 7 covers the installation of emergency and standby power systems. Key requirements include:
Generator Room / Enclosure
- The generator and associated equipment must be installed in a dedicated room or weatherproof enclosure
- The room must have adequate ventilation for combustion air and heat rejection
- Fire-rated separations may be required depending on building construction type
- Adequate access for maintenance and service must be provided
- Sound attenuation may be required per local codes
Fuel Supply System
This is one of the most important parts of NFPA 110 for fuel planning. The fuel-capacity margin itself is in Section 5.5.3.
- On-site fuel storage must cover the Class run time at full rated load. NFPA 110 Section 5.5.3 sets a fuel-capacity margin above the class run time. How it applies depends on edition and class; confirm with your AHJ.
- Fuel systems must include provisions to prevent overfilling
- Fuel storage tanks must comply with applicable codes (NFPA 30 for aboveground and underground tanks, and NFPA 37 for engine installations)
- Day tanks must have automatic filling and level controls
- Fuel quality must be maintained per the manufacturer’s recommendations
- Fuel piping and fittings must be rated for the fuel type and service conditions
Whether a margin applies, and how large it is, depends on the edition and Class your AHJ enforces. Holding exactly the fuel for your Class run time may not be enough if your AHJ applies Section 5.5.3, so confirm before you size tanks.
Transfer Switch Requirements
- Automatic Transfer Switches (ATS) must meet UL 1008 listing requirements
- Level 1 systems must have automatic operation — no manual intervention required for initial transfer
- Transfer switches must be exercised regularly as part of the testing program
- Bypass-isolation transfer switches are recommended so a switch can be maintained without losing protection, and may be required by the AHJ
- Multiple ATS units in a facility must be coordinated to prevent generator overload during sequential transfer
Chapter 8: Routine Maintenance and Operational Testing
NFPA 110 Chapter 8 establishes the testing and maintenance schedule that facilities must follow. This is where most compliance issues arise — not from installation problems, but from inadequate testing programs and documentation.
Weekly: Visual Inspection
- Inspect the generator for leaks, unusual conditions, and general cleanliness
- Check fuel level
- Check oil level
- Check coolant level
- Inspect battery connections and electrolyte level
- Verify block heater is operating (unit should be warm to the touch)
- Check for any alarm conditions on the controller
- Record all findings in the inspection log
Monthly: 30-Minute Load Test
NFPA 110 Section 8.4.2 requires monthly testing under load conditions:
- Run the generator for a minimum of 30 minutes
- Operate under a load of at least 30% of the nameplate kW rating, or a load that maintains the manufacturer’s minimum exhaust gas temperature
- Operate every transfer switch (NFPA 110-2019 §8.4.6)
- Record starting time, voltage, frequency, current, oil pressure, coolant temperature, and runtime
- Document any abnormalities or maintenance needs
- If monthly exercises can’t reach 30% load or the manufacturer’s minimum exhaust temperature, NFPA 110 requires an annual supplemental load test (load bank test planner)
Important: A monthly exercise below 30% load counts only if it maintains the manufacturer’s minimum exhaust gas temperature; otherwise the annual supplemental load test is required. Sustained running below about 30% load promotes wet stacking (unburned fuel accumulation in the exhaust system), which damages the generator and reduces reliability.
Annual Requirements
- Full operational test (best practice): Simulate a utility power failure and verify the complete system responds correctly — generator start, ATS transfer, load pickup, and return to normal when utility power is restored
- Fuel quality testing: NFPA 110 requires an annual fuel quality test using ASTM methods; many operators test twice a year. A typical lab panel (our recommendation, not an NFPA 110 list) checks specific gravity, water and sediment, flashpoint, viscosity, sulfur content, and cetane number
- Supplemental load test (only if monthly exercises can’t reach 30% load or the manufacturer’s minimum exhaust temperature): 2013 and later editions (Section 8.4.2.3) require at least 50% of nameplate for 30 minutes, then at least 75% for 60 minutes. The 2010 edition, enforced for health care, requires 25% for 30 minutes, 50% for 30 minutes, and 75% for 60 minutes
- Transfer switch maintenance (best practice): Inspect, clean, and test all automatic transfer switches per manufacturer recommendations. NFPA 110 requires every transfer switch to be operated monthly.
- Battery load testing (best practice): Load test or impedance test generator starting batteries, commonly quarterly. NFPA 110 Annex A, which is advisory, recommends it; the required check is the weekly battery inspection.
- Comprehensive system inspection: Review all components of the emergency power system for wear, damage, and code compliance
36-Month: Extended Load Test
Every 36 months (3 years), NFPA 110 requires an extended load test:
- For Level 1 systems, at least once every 36 months, run for the Class duration or 4 hours, whichever is less, at 30% or more of nameplate kW (Section 8.4.9)
- Monitor fuel consumption, oil pressure, coolant temperature, voltage, and frequency throughout
- This test verifies that the generator can sustain operation for an extended period and that the cooling, lubrication, and fuel systems perform as designed
- If the building load cannot reach 30% of nameplate, a load bank is used to supplement it
This 36-month test is critical for identifying issues that don’t appear in 30-minute monthly tests, including cooling system deficiencies, fuel system restrictions, and exhaust backpressure problems. The Load Bank Test Planner builds the recommended test sequence.
Fuel Storage: Estimating Fuel for Your Class or Plan
Here is how to estimate fuel for a run-time target, such as the Class your AHJ sets or a 96-hour plan:
Formula:
Fuel needed (estimate) = Hourly consumption × Runtime hours. Any Section 5.5.3 margin is a separate tank-capacity check based on full-load fuel for the Class run time; confirm it with your AHJ.
Example:
A hospital with a 750 kW generator running at 75% load:
- Base consumption at 75% load: ~39.4 gallons/hour
- Estimated altitude adjustment (Denver, 5,280 ft; check your manufacturer’s derate curve): 39.4 × 1.05 = 41.4 gal/hr
- Estimated age allowance (12 years; a BackupPower.ai assumption): 41.4 × 1.08 = 44.7 gal/hr
- 96-hour plan estimate: 44.7 × 96 = 4,291 gallons
- With a 20% planning reserve (a BackupPower.ai suggestion): 4,291 × 1.20 = 5,149 gallons
In this example, a single 5,000-gallon tank (about 4,500 gallons usable, assuming 90%) would cover roughly 100 hours on site (4,500 ÷ 44.7), before any reserve or Section 5.5.3 margin. Whether that is enough depends on your Class, edition and plan; if it falls short, add storage or a supplemental fuel delivery agreement.
Use our 96-Hour Fuel Rule Calculator to run this calculation for your specific facility.
Transfer Switch Requirements in Detail
The transfer switch is the critical link between utility power and generator power. NFPA 110 requirements for transfer switches include:
- 10-second transfer (Type 10): The complete sequence — utility failure detection, generator start, and load transfer — must complete within 10 seconds for Type 10 systems, the usual hospital requirement
- Automatic operation: The ATS must detect utility failure and initiate the transfer sequence without manual intervention
- Return transfer: When utility power is restored and stable, the ATS must retransfer the load back to utility power (typically after a time delay to verify stable utility)
- Exercising: Transfer switches must be operated (exercised) during monthly generator tests to keep mechanical components functioning
- Bypass/isolation: A bypass-isolation design is recommended, and may be required by the AHJ, so the ATS can be taken out of service for maintenance without de-energizing the emergency circuit
Recordkeeping Requirements
NFPA 110 requires a permanent record of inspections, tests, exercising, operation and repairs. Surveyors expect to see:
- Weekly inspection logs with dates, findings, and inspector signatures
- Monthly test records including all measured parameters (voltage, current, frequency, temperatures, pressures)
- Annual fuel test results (ASTM lab reports)
- 36-month extended load test reports
- Maintenance and repair records
- Fuel delivery records and tank fill dates
- Transfer switch test and maintenance records
- Any abnormality reports and corrective actions taken
Records must be maintained on-site and available for review. Many facilities use electronic maintenance management systems, which is acceptable as long as records can be produced during an inspection.
Which Edition Applies?
NFPA 110 is revised on a 3-year cycle, and the current edition is NFPA 110-2025. CMS and the Joint Commission still enforce the 2010 edition for health care. For the changes in any edition, see NFPA’s NFPA 110 document page.
Check with your Authority Having Jurisdiction (AHJ) to determine which edition of NFPA 110 is enforced in your jurisdiction.
Frequently Asked Questions
Is NFPA 110 the same as NFPA 99?
No. NFPA 110 covers emergency and standby power systems generally, while NFPA 99 (Health Care Facilities Code) is specifically for healthcare facilities. NFPA 99 references NFPA 110 for emergency power requirements but adds healthcare-specific provisions for essential electrical systems, including life safety, critical, and equipment branch requirements. Healthcare facilities must comply with both.
Does NFPA 110 apply to natural gas generators?
Yes. NFPA 110 applies to all emergency and standby power systems regardless of fuel type. However, the fuel storage requirements (including any Section 5.5.3 margin) apply differently to natural gas — piped utility gas doesn’t require on-site storage calculations, but the standard still requires a reliable fuel supply for the required runtime duration.
What happens if we fail a monthly test?
If a monthly test reveals a problem (failure to start, abnormal operating parameters, ATS malfunction, etc.), the issue must be corrected immediately and documented. The generator is effectively out of compliance until repaired and retested. Most facilities should have repair service agreements with response time guarantees for this reason.
How long do we need to keep records?
NFPA 110 doesn’t specify a minimum retention period, but best practice is to retain all testing and maintenance records for the life of the equipment or a minimum of 5 years, whichever is longer. Surveyors commonly ask for recent testing records and the most recent 36-month test, so keep them readily available.
Can we use portable generators to meet NFPA 110?
NFPA 110 generally requires permanently installed emergency power systems for Level 1 and Level 2 applications. Portable generators may be used as temporary emergency power during equipment failure or maintenance, but they typically cannot serve as the primary NFPA 110 emergency power system. Exceptions may exist for specific facility types and local jurisdictions.
Check your compliance: Use the 96-Hour Fuel Rule Calculator →
Related Resources
- The 96-Hour Fuel Rule Explained — How CMS, Joint Commission, and NFPA 110 requirements work together to shape healthcare fuel planning.
- 96-Hour Fuel Rule Calculator — Run the numbers for your facility with our free compliance calculator.
- Healthcare Backup Power Compliance Hub — All healthcare compliance tools, calculators, and guides in one place.
- Load Bank Test Planner — Plan your 36-month extended load test.
FuelCare performs annual fuel quality testing required by NFPA 110, as well as fuel polishing and generator fuel system maintenance for facilities across the United States. Schedule your annual fuel test.