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.