NFPA 110 Generator Testing: An Overview

The National Fire Protection Association (NFPA) creates minimum standards for fire safety, egress safety, and other types of safety in commercial buildings. Included in the NFPA's safety standards is a code for testing and maintaining emergency power supply systems (EPSS): NFPA 110. If your building contains a generator, practicing the code can ensure that it performs as expected during a power outage. Below are the basic testing requirements for industrial generators according to NFPA 110. For a full list of requirements, building managers should contact the NFPA, or a commercial power solutions provider.

NFPAtesting for industrial generators
If a building is required to have a Level 1 or Level 2 generator, the following types of NFPA 110 generator testing should be performed in preparation for a power outage. Experts trained in EPSS technology should carry out these tests.

Section 8.4.2
An EPSS must be exercised under load once a month for at least thirty minutes. The test should be conducted using one of the following two methods:  

• Loading that achieves a minimum temperature for exhaust gas based on the manufacturer's recommendations.
• Under normal operating temperature while running at a minimum of 30% of the nameplate Kilowatt rating.

For generators that cannot operate until their water pressure and oil pressure have stabilized, the tests above should be terminated before the thirty minutes expire. This reduces the time a generator is unavailable for operation.

Section 8.2.4.3
Diesel powered generators that do not meet the requirements set forth in Section 8.4.2 should be exercised monthly for at least thirty minutes using the available EPSS load, and yearly for two hours using a supplied load. For yearly tests, the two hours should be broken down as follows:

• 30 minutes at 25% of the nameplate Kilowatt rating.
• 30 minutes at 50% of the nameplate Kilowatt rating.
• 60 minutes at 75% of the nameplate Kilowatt rating.

A load bank can provide the "supplied load" required for tests under Section 8.2.4.3. Load banks, as well as diesel-powered generators, are available for short-term and long-term rental from commercial power solution providers.

The scope and benefits of NFPA EPSS testing

The requirements above are not a complete list of NFPA 110 generator testing requirements. To determine the necessary maintenance measures and tests needed for your unique generator, consult the code in its entirety. By following its requirements, the following benefits can be realized:

• Improved reliability of emergency backup lighting.
• Reduced possibility of electricity interruption in critical facilities.
• Reduced layover time in break before make generators.
• Improved emergency power generation capacity.

Implementing an EPSS is the first step toward powering your building in the event of a power outage, and regular maintenance and tests are needed to ensure its function. To have monthly and annual tests performed; building managers should consult commercial power solution providers. Other services provided by commercial power solutions providers include: retrofitting and modernization measures, new installations, infrared scanning, breaker tests, arc flash analysis and training, healthcare utility management, generator rentals, scheduled maintenance, and repairs.

NFPA 110 Requirements for Transfer Switch Maintenance

The National Fire Protection Association (NFPA) develops and maintains minimum safety standards for commercial and large residential buildings. Expressed as safety codes, the standards address the safety of various building systems, including emergency power supply systems (EPSS). Requirements for EPSS maintenance inspections are contained in the NFPA 110, which also addresses generator testing. Below are requirements for generator transfer switch maintenance according to the NFPA 110.

Transfer Switch Maintenance Requirements
The following is an overview, not a complete documentation, of transfer switch inspection requirements. For full documentation of NFPA 110 requirements, building managers should contact the NFPA, or an emergency power solution provider.

Maintaining a transfer switch is a critical part of generator maintenance. The NFPA's inspection requirements for switches for Level 1 and Level 2 generators are as follows:

Examination for Overheating
Overheating eventually produces visual evidence, particularly the discoloration or blistering of insulation found on conductors. The surfaces of conductors may also show signs of pitting or melting. These signs may be the result of arcing, and usually precipitate repairs and/or parts replacement.

Examination for Dust and Dirt
Regardless of the cleanliness of a generator room, dust and dirt gradually accumulate on the surface and inner workings of switches. Removing dust and dirt prevents their accumulation from sabotaging electrical connections and contacts.

Examination of connections
If the electrical connections of a switch malfunction, it will not transmit the signal to initiate generator startup. Connections should be inspected for looseness and signs of overheating. If looseness or overheating is detected, connections should be tightened or replaced.

Examination of contacts
Contacts should be inspected for looseness, signs of corrosion, and overheating. Signs of corrosion may appear as oxidization or acidic deterioration, and overheating may leave carbon traces. If the first two signs are present, contacts should be replaced. If the third sign is present, further examination should occur.

The inspections above are recommended on an annual basis. However, the 2005 edition of the NFPA 110 recommends them on a quarterly basis, with a single major inspection and three minor inspections every year. This inspection schedule could be valuable for buildings that require constant electricity to support critical functions, such as hospitals, data centers, and first response organizations.

Scheduling Transfer Switch Inspections
Maintenance and testing requirements for transfer switches are contained in Chapter 8 of the NFPA 110. Section 8.4.5 states that a "properly instructed individual" (i.e. a person with extensive training in EPSS examination procedures) should oversee routine EPSS inspections. If you do not employ a worker who is trained in EPSS inspection, hiring a commercial power solution provider that specializes in emergency power equipment testing and inspection is the best option.

In addition to performing the inspections above, a commercial power solutions provider may also perform infrared scanning-a preventative maintenance measure that identifies problems in EPSS components before they cause more extensive problems. Other services performed by a commercial power solutions provider include: retrofits and modernization measures, breaker testing, new installations, repairs, arc flash analysis and training, healthcare utility management, generator rentals, scheduled maintenance, and load bank testing.