Understanding NFPA 110 Generator Testing Requirements

If your facility relies on an emergency generator, understanding NFPA 110 is not optional—it is essential. A power outage at a hospital, data center, or critical site can disrupt operations. It can endanger patient safety and put your facility out of compliance with the AHJ.

NFPA 110, Standard for Emergency and Standby Power Systems, establishes the minimum performance requirements for an emergency power supply system (EPSS). Covering design, installation, maintenance, and testing. This article covers the key generator testing requirements you need to know. Updated to reflect the NFPA 110, 2025 Edition.

What Is NFPA 110?

NFPA 110 classifies emergency and standby power systems using three criteria:

• Type: The maximum time allowed for power restoration. Type 10 systems must restore power within 10 seconds of a utility failure—the standard for healthcare facilities.
• Class: The minimum run time the EPSS must sustain without refueling. Ranging from Class 0.083 (5 minutes) to Class X (a user-defined duration).
• Level: Level 1 systems serve loads where a power failure could result in loss of life or serious injury. Level 2 systems support less critical loads.

Both levels require the same maintenance rigor. The mechanical and electrical systems are identical. The equipment must be online within a specified period based on the Type.

The standard covers the entire EPSS. This includes the generator (emergency power supply) and transfer switches. It also includes distribution equipment, controls, and supervisory equipment. It covers all accessory systems needed to deliver power to essential loads.

Monthly Generator Testing Requirements

NFPA 110 requires monthly exercise of the entire EPSS under load—not just running the generator. The monthly test is the most important operational check in your emergency power program. Qualified personnel must perform it (NFPA 110, 8.4.8).

NFPA 110 defines a Qualified Person as someone with skills and knowledge about EPSS equipment. They can operate, maintain, repair, and test EPSS equipment and installations. They have safety training to spot and avoid hazards.

Two Ways to Meet the Loading Requirement

NFPA 110, paragraph 8.4.2, provides two methods for meeting the monthly loading requirement:

• Exhaust gas temperature method: The generator reaches the minimum exhaust gas temperature recommended by the manufacturer, confirming adequate combustion.
• 30% nameplate method: The generator operates at normal temperature while running at no less than 30% of its nameplate kW rating.

The generator must run under load for a minimum of 30 continuous minutes. Timed from the moment the EPS accepts the load. A minimum 5-minute unloaded cool-down period follows. Making the total test duration approximately 40–45 minutes, including startup, transfer, loaded run, and cool-down.

For healthcare facilities, NFPA 99 is more prescriptive. Generator sets must be tested 12 times per year at intervals of not less than 20 days nor more than 40 days. This is stricter than NFPA 110's "at least monthly" wording. It prevents back-to-back tests and long gaps between tests.

Cold Start Requirements

NFPA 110, paragraph 8.4.4, is explicit: load tests of generator sets shall include complete cold starts. A cold start means the EPS starts and accepts full load without any manual pre-warming or idle period. The engine starts, reaches rated speed and voltage, and the transfer switches move essential loads to the generator. This happens within the 10-second window required for Type 10 installations.

A real power outage does not give you a warm-up period. If your monthly test does not match real conditions, you are not testing your system. You are practicing under ideal conditions that will not exist when you need it.

Initiate the test from the automatic transfer switch (ATS) test switch, not the generator panel. Starting from the ATS, tests the full signal chain. From loss-of-power detection through engine start, voltage stabilization, and load transfer.

Generator Load Bank Testing Requirements

If your generator does not reach 30% of its nameplate kW rating during the monthly test—and exhaust gas temperatures do not demonstrate adequate combustion—you cannot simply continue testing at low load indefinitely. NFPA 110 requires an annual supplemental load run using a load bank or other supplemental load source.

Why Generator Load Testing Matters

A generator that runs at a light load month after month can build up damage. This damage may not appear until a real emergency needs full output. Chronic light loading can cause wet stacking, which is unburned fuel in the exhaust. It can also cause carbon deposits on pistons and injectors. Fuel and oil can mix and thin out. Water can also contaminate the lubricating oil. The annual load bank test is the corrective measure. Pushing the engine through higher loads to burn off deposits and verify performance.

The Annual Load Bank Test Protocol (NFPA 110, 2025 Edition)

The current load run protocol under NFPA 110, paragraph 8.4.2.4 requires:

• 50% of nameplate kW for 30 continuous minutes
• 75% of nameplate kW for 1 continuous hour
• Total: at least 1.5 continuous hours

One critical requirement that is often overlooked: NFPA 110, paragraph 8.4.2.3 requires that equivalent loads (load banks) be automatically replaced with essential building loads if normal power fails during the test. Manual switching does not satisfy this requirement. The annual load bank test supplements your monthly testing program—it does not replace it.

Transfer Switches and Circuit Breakers

Generator testing is not just about the engine. The transfer switches and circuit breakers are critical links in the emergency power chain. NFPA 110 has specific requirements for each.

Transfer Switch Testing

Transfer switches must be operated monthly (NFPA 110, 8.4.6). The monthly test consists of electrically operating the switch from the normal position to the emergency position. Then returning it to the normal position.

Where multiple ATSs are part of the EPSS, the test-initiating ATS should be rotated each month to verify the starting function on each switch (8.4.3.2).

Four time delays form a sequential chain controlling the entire power failure and restoration cycle: time delay on start, time delay on transfer to emergency, time delay on restoration to normal (5-minute minimum), and time delay on shutdown (5-minute minimum). Misconfiguring any one of these can result in nuisance starts, premature retransfers, or engine damage.

Circuit Breaker Testing

EPSS circuit breakers for Level 1 systems—including main and feeder breakers between the EPS and the transfer switch load terminals—must be exercised annually with the EPS in the "off" position (NFPA 110, 8.4.7). Circuit breakers rated in excess of 1,000 volts must be exercised every 12 months and tested under simulated overload conditions every 3 years (8.4.7.1).

Triennial (36-Month) Testing

Level 1 EPSS installations must undergo a comprehensive system test at least once every 36 months (NFPA 110, 8.4.9). This triennial test is the most demanding test in the NFPA 110 framework:

• The EPSS must run continuously for the duration of its assigned class—or 4 continuous hours, whichever is less.
• The test is initiated by operating at least one ATS test function and then activating the remaining ATSs, or by opening all normal power supply breakers.
• The test verifies that the entire system—generator, transfer switches, distribution, fuel system, cooling, and controls—can sustain essential loads through a prolonged outage.

This test confirms that your backup power system can support critical operations during an extended emergency, including verifying fuel transfer pump operation and adequate fuel supply for the full run duration.

Acceptance Testing

NFPA 110 requires acceptance testing whenever a new EPSS is installed or after significant modifications. The acceptance test verifies that the generator starts within the required time window (10 seconds for Type 10 systems), the system delivers power to essential loads as designed, transfer switches function properly under simulated power loss, and all safety devices and controls operate correctly.

The results of the acceptance test—along with manufacturer certifications and a certified analysis of the system—must be made available to the AHJ at the time of testing.

Documentation and Recordkeeping

NFPA 110, paragraph 8.3.3 requires a written schedule for routine maintenance and operational testing. This is not optional, and it will be reviewed by every AHJ that inspects your facility. NFPA 110, paragraph 8.5 requires that permanent records be created and maintained for all EPSS inspections, tests, repairs, and modifications.

A complete monthly testing record should capture: engine hours, date and time of test, nameplate data, ATS identification, transfer times, voltage and amperage per phase, frequency, oil pressure, coolant and exhaust temperatures, retransfer data, cool-down readings, and switch position verification. This data serves three purposes: confirming the system functioned, creating a comparison baseline for trending, and building the permanent record required by the code.

Records must include the date of the maintenance report, identification of servicing personnel, notation of any unsatisfactory conditions and corrective actions taken, and testing of any repairs within the manufacturer's recommended timeframe. While NFPA 110 does not specify a retention period, the AHJ may define one, and records must be available upon request.

NFPA 110 Generator Testing Form

Use the form on this page to access our fillable PDF monthly test form. Enter your information in the sidebar, and a download link will appear — no page redirect, no waiting. The form includes fields for voltage, amperage, time delays, retransfer readings, and every data point required by NFPA 110 for your permanent testing records.

Qualified Personnel

NFPA 110, paragraph 8.4.8, requires that EPSS components be maintained and tested by qualified persons. Monthly testing involves live electrical equipment, rotating machinery, high-temperature exhaust systems, and battery systems that can produce explosive gases. Personnel must understand the hazards present and the proper procedures for every phase of the test.

Training programs should consider the requirements of local, state, and federal authorities. Some AHJs have specific regulations or certification criteria for generator mechanics. OSHA mandates training in areas including electrical safety, personal protective equipment, and hazard communication.

The Authority Having Jurisdiction (AHJ)

The AHJ enforces NFPA 110 compliance at your facility. Depending on your jurisdiction, this may be a local fire marshal, a state health department, a CMS surveyor, or The Joint Commission. Facility managers must maintain detailed records of all testing and maintenance, promptly address deficiencies identified during inspections, and ensure that all testing is performed by qualified personnel. Your written maintenance schedule and permanent test records are the first things an AHJ will review during an inspection.

Best Practices for EPSS Management

To maintain an effective and compliant emergency power system:

• Build your maintenance schedule from the manufacturer's recommendations first. The NFPA 110 annex figures are fallback guidelines, not master protocols.
• Test during periods of peak facility load whenever practical. A test at 2 a.m. on a Sunday confirms the system starts. But, it does not confirm the system can handle the demand it would face at 2 p.m. on a Wednesday.
• Educate EPSS personnel. Monthly testing involves significant safety hazards, and NFPA 110 requires qualified persons for all EPSS testing and maintenance.
• Consider providing a temporary alternate power source whenever the emergency generator is out of service for maintenance or during routine testing (NFPA 110, 8.1.2).
• Keep at least two sets of instruction manuals, special tools, and spare parts on-site. For Level 1 systems, one set should be near the equipment, and the other should be in a separate location (NFPA 110, 8.2.1–8.2.4).

Frequently Asked Questions

How often does NFPA 110 require generator testing?

NFPA 110 requires monthly exercise under load for the entire EPSS. Healthcare facilities must test 12 times per year, with intervals between 20 and 40 days, per NFPA 99. Additionally, Level 1 EPSS installations require a comprehensive triennial (36-month) test.

What is a generator load bank test?

A generator load bank test uses a portable or permanently installed load device to apply a controlled, adjustable load to the generator. Load bank testing is required when the generator does not reach 30% of its nameplate kW rating during monthly tests, and exhaust temperatures do not confirm adequate combustion. The current NFPA 110 (2025) annual load bank test protocol requires 50% of the nameplate for 30 minutes, followed by 75% for 1 hour.

What are the emergency generator testing requirements for hospitals?

Hospitals must comply with both NFPA 110 and NFPA 99 (Health Care Facilities Code®). NFPA 99 requires 12 tests per year at 20- to 40-day intervals, complete simulated cold starts, and automatic transfer of all essential electrical system loads. The 10-second transfer criterion applies to Life Safety and Critical Branch loads, and CMS surveyors will review your testing records during inspections.

Is there an NFPA 110 generator testing form?

While NFPA 110 does not publish a standardized form, the standard requires permanent records that capture specific data points for each test. MGI offers a free fillable PDF monthly test form designed to meet these documentation requirements. [Download in sidebar]

What happens if my generator fails the monthly test?

You must do an annual supplemental load run per NFPA 110, 8.4.2.4. Do this if your generator does not meet the monthly load rule. The monthly rule is 30% nameplate load or an adequate exhaust temperature. Any unsatisfactory conditions must be documented with corrective actions taken. Consistent failure to meet the 10-second transfer criterion during monthly tests indicates a maintenance issue that requires investigation.

Conclusion

Understanding NFPA 110 generator testing requirements is essential for maintaining the reliability of your emergency power system. The standard sets minimum benchmarks: monthly cold-start load tests and annual load bank tests when monthly loads fall short. It also requires system tests every three years. It requires transfer switch and circuit breaker exercise. It also requires full documentation for every test.

These requirements exist for one reason: to make sure your emergency system powers essential loads during an outage. Regular testing, proper documentation, and qualified personnel are not just compliance checkboxes. They are the foundation of equipment readiness and occupant safety.