Specifications

Readiness of emergency power is a key consideration in safeguarding building occupants in the event of a disruption of the normal utility supply. NFPA 111 covers performance requirements for stored electric energy systems providing an alternate source of electrical power in buildings and facilities during interruption of the normal power source.

NFPA 791 covers recommended procedures for evaluating unlabeled electrical equipment for compliance with nationally recognized standards. Criteria provide guidance to third-party field evaluation bodies (FEBs) on how to perform evaluations of unlabeled electrical equipment in a consistent and reliable manner, thus assisting regulating authorities who make product and related installation approval decisions and facilitating acceptance of the results. Specific areas covered include pre-site preparation, construction inspection, electrical testing, and reporting, and documentation.

1.1 These requirements cover fixed and location-dedicated electric room heating equipment rated 600 V or less to be employed in ordinary locations in accordance with the NEC, ANSI/NFPA 70. 1.2 These requirements do not cover movable heaters, wall- or ceiling-hung heaters, baseboard heaters, duct heaters, central-heating furnaces, fan-coil units, panel- or cable-type radiant-heating equipment, electric boilers, or any other electric heating equipment or appliances covered in or as a part of separate, individual requirements.

These requirements cover ESS that are intended to store energy from power or other sources and provide electrical or other types of energy to loads or power conversion equipment. The ESS may include equipment for charging, discharging, control, protection, communication, controlling the system environment, fuel or other fluid movement and containment, etc. The system may contain other ancillary equipment related to the functioning of the energy storage system.

(a) Except for Class A digital devices, the field strength of radiated emissions from unintentional radiators at a distance of 3 meters shall not exceed the following values:

(b) The field strength of radiated emissions from a Class A digital device, as determined at a distance of 10 meters, shall not exceed the following:

(c) In the emission tables above, the tighter limit applies at the band edges. Sections 15.33 and 15.35 which specify the frequency range over which radiated emissions are to be measured and the detector functions and other measurement standards apply.

(d) For CB receivers, the field strength of radiated emissions within the frequency range of 25-30 MHz shall not exceed 40 microvolts/meter at a distance of 3 meters. The field strength of radiated emissions above 30 MHz from such devices shall comply with the limits in paragraph (a) of this section.

(e) Carrier current systems used as unintentional radiators or other unintentional radiators that are designed to conduct their radio frequency emissions via connecting wires or cables and that operate in the frequency range of 9 kHz to 30 MHz, including devices that deliver the radio frequency energy to transducers, such as ultrasonic devices not covered under part 18 of this chapter, shall comply with the radiated emission limits for intentional radiators provided in § 15.209 for the frequency range of 9 kHz to 30 MHz. As an alternative, carrier current systems used as unintentional radiators and operating in the frequency range of 525 kHz to 1705 kHz may comply with the radiated emission limits provided in § 15.221(a). At frequencies above 30 MHz, the limits in paragraph (a), (b), or (g) of this section, as appropriate, apply.

(f) For a receiver which employs terminals for the connection of an external receiving antenna, the receiver shall be tested to demonstrate compliance with the provisions of this section with an antenna connected to the antenna terminals unless the antenna conducted power is measured as specified in § 15.111(a). If a permanently attached receiving antenna is used, the receiver shall be tested to demonstrate compliance with the provisions of this section.

(g) As an alternative to the radiated emission limits shown in paragraphs (a) and (b) of this section, digital devices may be shown to comply with the standards contained in Third Edition of the International Special Committee on Radio Interference (CISPR), Pub. 22, “Information Technology Equipment - Radio Disturbance Characteristics - Limits and Methods of Measurement” (incorporated by reference, see § 15.38). In addition:

(1) The test procedure and other requirements specified in this part shall continue to apply to digital devices.

(2) If, in accordance with § 15.33 of this part, measurements must be performed above 1000 MHz, compliance above 1000 MHz shall be demonstrated with the emission limit in paragraph (a) or (b) of this section, as appropriate. Measurements above 1000 MHz may be performed at the distance specified in the CISPR 22 publications for measurements below 1000 MHz provided the limits in paragraphs (a) and (b) of this section are extrapolated to the new measurement distance using an inverse linear distance extrapolation factor (20 dB/decade), e.g., the radiated limit above 1000 MHz for a Class B digital device is 150 uV/m, as measured at a distance of 10 meters.

(3) The measurement distances shown in CISPR Pub. 22, including measurements made in accordance with this paragraph above 1000 MHz, are considered, for the purpose of § 15.31(f)(4) of this part, to be the measurement distances specified in this part.

(h) Radar detectors shall comply with the emission limits in paragraph (a) of this section over the frequency range of 11.7-12.2 GHz.

The document describes the various methods used for grounding electrical systems and the non-current carrying metal parts of electrical wiring systems and equipment and also discusses the advantages and disadvantages of the different grounding methods, and the means employed to safeguard property from arc damage and fire.

The document describes modern procedures and practices for protecting industrial power distribution systems and associated equipment from damage caused by overvoltages due to lightning, switching, or a system abnormality.

The document describes the types, operation, and protection of emergency and standby power systems, and provides guidelines for their application. Recommendations are included for the arrangement and protection of fuel supplies feeding emergency and standby power systems.

The guide applies to all types of static power converters used in industrial and commercial power systems. The problems involved in the harmonic control and reactive power compensation of such converters are addressed, and an application guide is provided. Limits of disturbances to the AC power distribution system that affect other equipment and communications are recommended.