UL 924-2016 pdf download – Emergency Lighting and Power Equipment.
4.33 LAMPHEAD – As applicable to unit equipment, a lamp assembly mounted externally to the main enclosure of the equipment with a swivel or equivalent mounting means so as to be adjustable. 4.34 LEGEND – Text (in English or other languages as appropriate for the installation site) or graphical symbols intended to transmit a specific message associated with life safety, in accordance with an adopted building or fire code. 4.35 LIMITING IMPEDANCE CIRCUIT – A circuit supplied by an impedance that, under any load condition including when a direct short is applied across the source output: a) Has a calculated power dissipation of 1 5 W or less, and b) Does not incur any opened or shorted components. The limiting impedance shall additionally function under any single fault condition unless it consists of a single resistor, or of a single capacitor that complies with the Standard for Fixed Capacitors for Use in Electronic Equipment – Part 1 4: Sectional Specification: Fixed Capacitors for Electromagnetic Interference Suppression and Connection to the Supply Mains, UL 60384-1 4. See Determination of Limiting Impedance Circuit Status, Section 51 . 4.36 LOW-FREQUENCY INVERTER – An arrangement of solid-state circuitry designed to convert direct-current power to low-frequency (50 – 800 hertz), alternating current and the voltage required to operate lighting and power equipment. 4.37 LOW-VOLTAGE, LIMITED-ENERGY CIRCUIT – A circuit supplied by a source of open circuit potential below the risk of electric shock and maximum 8 A available current measured after one minute of operation. See Section 50. 4.38 LUMINANCE – The amount of light emitted from a surface, measured in foot-lamberts or candelas per square meter. 4.39 MULTI-CIRCUIT DISTRIBUTION EQUIPMENT – Any multi-circuit distribution panel incorporating individual branch circuit overcurrent protection. This equipment may be provided with individual branch circuit monitoring control relays.
4.50 ROUTINE OPERATION – Operation of a test switch located inside or outside the overall enclosure, resetting of switches and circuit breakers, and similar operations. 4.51 SEALED BATTERY/CELL – A battery/cell that has no provision for the addition of water or electrolyte or for external measurement of electrolyte specific gravity. 4.52 SELF-LUMINOUS EXIT SIGN – A sign with an integral legend that is powered continuously by a self-contained energy source other than a battery, such as radioactive tritium gas. Operation of a self-luminous exit sign is independent of external power supplies or other external forms of energy. This definition does not include exit signs dependent upon photoluminescent materials. 4.53 SERVICE – Tasks intended to be performed on-site by qualified personnel and that require a tool to access any compartment for performance of the task. 4.54 TRANSLUCENT – The property of letting light through without being transparent. As applicable to exit signs, a luminous surface that is not transparent, but provides the same effect as a translucent material that is illuminated from the back is also considered to be translucent. For example, a composite construction consisting of a transparent material applied over a luminous non-transparent surface as in edge-lighted exit sign constructions is considered to be translucent. 4.55 UNFILTERED – In the context of a luminaire intended to activate a photoluminescent exit sign, the lack of a lens or diffuser that removes any appreciable portion of the UV spectrum. 4.56 UNIT EQUIPMENT – A complete, enclosed unit assembly, consisting of a rechargeable battery, a battery charging means, provisions for one or more lamps either mounted on the equipment or remote or both, and a device arranged to energize the lamps automatically upon failure of the normal supply. Terminals or leads are provided for the connection of remote lamps.