Nfpa Standard For The Installation Of Lightning Protection Systems

Front 1

air terminal

Back 1

a strike termination device that is a receptor for attachment of flashes to the lightning protection system and is listed for the purpose

Front 2

bonding

Back 2

an electrical connection between an electric conductive object and a component of lightning protection system that is intended to significantly reduce potential differences created by lightning currents

Front 3

cable

Back 3

a conductor formed of a number of wires stranded together

Front 4

catenary lightning protection system

Back 4

a lightning protection system consisting of one or more overhead ground wires

Front 5

combination waveform generator

Back 5

a surge generator with a 2-ohm internal impedance producing a 1.2/50 μs short-circuit current weaveshape

Front 6

bonding conductor

Back 6

a conductor used for potential equalization between grounded metal bodies or electrically conductive objects and a lightning protection system

Front 7

loop conductor

Back 7

a conductor encircling a structure that is used to interconnect grounding electrodes, main conductor, or other electrically conductive bodies

Front 8

main conductor

Back 8

a conductor intended to be used to carry lightning currents between strike termination devices and grounding electrodes

Front 9

copper-clad steel

Back 9

steel with a coating of copper bonding

Front 10

maximum discharge current (Imass)

Back 10

the maximum instantaneous value of teh current through the SPD having an 8/20 ps waveform

Front 11

nominal discharge current (I)

Back 11

peak value of 8/20 μs current waveform selected by the manufacturer for which an SPD remains functional after 15 surges

Front 12

fastener

Back 12

an attachment device used to secure the conductor to the structer

Front 13

flame protection

Back 13

self-closing gauge hatches, vapor seals, pressure-vacuum breather valves, flame arresters, or other effective means to minimize the possibility of flame entering teh vapor space of a tank

Front 14

flammable air-vapor mixtures

Back 14

flammable vapors mixed with air in proportions that will cause the mixture to burn rapidly when ignited

Front 15

flammable vapors

Back 15

a concentration of constituentes in air that exceeds 1-% of its lower flammable limit (LFL)

Front 16

flash point

Back 16

the minimum temperature at which a liquid or a solid emits vapor sufficient to form an ignitable mixture with air near the surface of the liquid or the solid

Front 17

gastight

Back 17

describes a structure so constructed that gas cannot enter or leave the structure except through vents or piping provided for that purpose

Front 18

grounded (grounding)

Back 18

connected (connecting) to ground or to a conductive body that extends the ground connection

Front 19

heavy-duty stack

Back 19

a smoke or vent stack with a flue that has a cross-sectional area of the flue greater than 0.3 squared m (500 squared inches)

Front 20

lightning protection system

Back 20

a complete system of strike termination devices, conductors (which could include conductive structural members), grounding electrodes, intern-connecting conductors, surge protective devices, and other connectors and fitting required to complete the system

Front 21

Class I Flammable Liquid

Back 21

any liquid that has a closed-cup flash point below 37.8ºC (100ºF) and a Reid vapor pressure not exceeding

Front 22

combustible liquid

Back 22

any liquid that has a closed-cup flash point of or above 37.8ºC (100ºF)

Front 23

class I material

Back 23

lightning conductors, air terminals, grounding electrodes, and associated fittings required for the protection of structures not exceeding 23 m (75 ft) in height

Front 24

class II materials

Back 24

lighting conductors, air terminals, grounding electrodes, and associated fittings required for the protection of structures exceeding 23 m (75ft) in height

Front 25

explosive materials

Back 25

materials, including explosives, blasting agents and detonators that are authorized for transportation

Front 26

sideflash

Back 26

an electrical spark, caused by differences of potential, that occurs between conductive metal bodies or between conducive metal bodies and a component of a lighting protection system or ground

Front 27

spark gap

Back 27

any short air space between two conductors that are electrically insulated from or remotely electrically connected to each other

Front 28

strike termination device

Back 28

a component of a lightning protection system that intercepts lighting flashes and connects them to a path to ground; they include air terminals, metal masts, permanent metal parts of structures and overhead ground wires installed in catenary lighting protection systems

Front 29

striking distance

Back 29

the distance over which the final breakdown of the initial lightning stroke to ground or to a grounded objects occurs

Front 30

metal-clad structure

Back 30

a structure with sides or roof, or both, covered with metal

Front 31

metal-framed structure

Back 31

a structure with electrically continuous structural members of sufficient size to provide an electrical path equivalent to that of lighting conductors

Front 32

suppressed voltage rating (SVR)

Back 32

a specific measured limiting voltage rating assigned to a surge protection device (SPD)

Front 33

surge

Back 33

a transient wave of current, potentiaol or power in an electric circuit; they do not include longer duration temporary overvoltages (TOV) consisting of an increase in the power frequency voltage for several cycles

Front 34

surge arrester

Back 34

a protective device for limiting surge voltages by discharging or bypassing surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions

Front 35

surge protective device (SPD)

Back 35

a device composed of any combination of linear or non linear circuit elements intended for limiting surge voltages on equipment by diverting or limiting surge current

Front 36

transient

Back 36

a subcycle disturbance in the ac waveform that is evidenced by a shapr, brief discontinuity of the waveform; it can be of either polarity and can be additive to, or subtractive from, the normal waveform

Front 37

transient voltage surge suppressor (TVSS)

Back 37

a protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capalbe of repeating these functions

Front 38

vapor opening

Back 38

an opening through a tank shell or roof that is above the surface of the stored liquid and that is provided for tank breathing, tank gauging, fire fighting, or other operating purposes

Front 39

maximum continuous operating voltage (MCOV)

Back 39

the maximum designated rms value of the power frequency voltage that can be continuously applied to the mode of protection of a surge protective device (SPD)

Front 40

measured limiting voltage (MLV)

Back 40

maximum magnitude of voltage that is measured across the terminals of the surge protection device (SPD) during the application of impulses of specified waveshape and amplitude

Front 41

nominal system voltage

Back 41

the nominal voltage (rms) of the power frequency supply

Front 42

normal operating voltage

Back 42

the normal ac power frequency voltage rating, as specified by the manufacturer to which the SPD may be connected

Front 43

voltage protection rating (VPR)

Back 43

a rating (or ratings) selected by the manufacturer based on the measured limiting voltage determined when the SPD is subjected to a combination waveform with an open circuit voltage of 6 kV and a short-circuit current of 3kA; the value is rounded up to the next highest V level

Front 44

watercraft

Back 44

all forms of boats and vessels up to 272 metric tons (300 gross tons) used for pleasure or commercial purposes, but excluding seaplanes, overcraft, vessels with a cargo of flammable liquids, and submersible vessels

Front 45

zone protections

Back 45

the space adjacent to a lightning protection system that is substantially immune to direct lightning flashes