-
NFPA 780 covers traditional lightning protection system installation requirements for which structures?
- -Ordinary Structures
- -Miscellaneous structures and special occupancies
- -Heavy-duty stacks
- -Watercraft
- -Structures containing flammable vapors, gases, liquids
-
What is the purpose of the NFPA 780 standard?
To provide for the safeguarding of persons and property from hazards arising from exposure to lightning.
-
What is sideflash?
An electrical spark, caused by differences of potential, that occurs between conductive metal bodies or between conductive metal bodies and a component of a lightning protection system or ground. 3.3.27
-
Spark Gap
Any short air space between two conductors that are electrically insulated from or remotely electrically connected to each other. 3.3.28
-
What is Zone of Protection?
The space adjacent to a lightning protection system that is substantially immune to direct lightning flashes. 3.3.39
-
Class I Solid Air Terminal Diameter
Copper?
Aluminum?
Copper 3/8"
Aluminum 1/2"
-
Tubular Air Terminal Diameter
Copper?
Aluminum?
Copper 5/8"
Aluminum 5/8"
Class I only!
-
Class I Main Conductor Size Each Strand
Copper?
Aluminum?
Copper 17 AWG
Aluminum 14 AWG
-
Class I Main Conductor Weight
Copper?
Aluminum?
Copper 187 lb/1000'
Aluminum 95 lb/1000'
-
What is the AWG size of Class I Copper Cable?
17 AWG
-
What is the AWG size of Class II Copper Cable?
15 AWG
-
What is the weight per length of copper Class I cable?
187.5 lbs/ 1000 feet
-
What is the weight per length of copper Class II cable?
375 lbs / 1000 feet
-
What is the AWG size of Class I aluminium cable?
14 AWG
-
What is the AWG size of Class II aluminium cable?
13 AWG
-
What is the weight per length of aluminum Class I cable?
95 lbs/1000 feet
-
What is the weight per length of aluminium Class II cable?
190 lbs/1000 feet
-
What is the diameter of a Class I copper solid air terminal?
3/8 inch
-
What is the diameter of a Class II copper solid air terminal?
1/2 inch
-
What is the diameter of Class I aluminium solid air terminal?
1/2 inch
-
What is the diameter of Class II aluminium solid air terminal?
5/8 inch
-
What is the diameter of copper and aluminium tubular air terminal?
5/8 inch
- AND
- Copper wall thickness is 0.32 inch
- Aluminium wall thickness is 0.64 inch
-
What class can tubular air terminals be used for?
Class I
-
What is the coarse and fine thread count of a 1/4" bolt?
20 and 28
-
What is the coarse and fine thread count for a 1/2" bolt?
13 and 20
-
What is the equation for slope?
Rise / Run
-
What year was the Lightning Protection Institute founded in?
1955
-
The Lightning Protection Institute promotes what?
-
What five elements need to be in place provide an effective lightning protection system?
- Strike termination devices
- Cable conductors
- Grounding electrode system
- Bonding
- Surge Protection Devices
-
What do lightning protection component materials need to be?
- Resistant to corrosion
- Protected from accelerated deterioration
-
What is electrically charged around us?
the atmosphere
-
What proper resistance is expected of a proper grounding electrode if the soil is of normal restivity?
less than 50 ohms
-
Copper components installed with 24 inches of a top of a chimney or vent that emits corrosive gases shall be what?
protected by lead or tin coating
-
Aluminum conductor shall not be attached or installed in what three circumstances?
- alkaline-base paint
- embedded in concrete/masonry
- subject to excessive moisture
-
Connector fitting shall be used at what three splices?
-
What amount of lbs shall all fittings be able to withstand in a pull test?
200 lbs
-
What is the minimum outside diameter of masonry anchors?
1/4"
-
How far above the object shall air terminals extend to protect the object?
no less than 10"
-
What is the wind resistance area of an ornament or decoration?
no greater than 20 square inches
-
What is the horizontal protected distance formula?
-
What happens to the zone of protection when the protection is no higher than 25 feet above grade?
1 to 2
-
What happens to the zone of protection when the protection is higher than 25 feet but lower than 50 feet?
1 to 1
-
How many feet above grade is it required to protect down conductors from mechanical damage?
6'
-
How many feet above grade is it required to protect down conductors that are entering into corrosive soil?
3 feet
-
What is the minimum diameter and length of ground rods?
1/2" and 8 ft long
-
How far shall ground rods extend vertically?
not less than 10'
-
What is the separation between any two ground rods?
at least the sum of the rod lengths
-
What is the bonding distance formula?
-
All grounded media and buried metallic conductors that can assist in providing a path for lightning currents in or on a structure shall be interconnected to the system within how many feet of the base of the structure?
12 feet
-
What standards does it require that buildings over 60 feet in height require a ground loop?
LPI 175 and NFPA 780
-
What does the interconnection of building system ground devices include?
- Lightning protection
- Electric service
- Communications
- Antenna system grounding
-
Within how many feet is it required to bond underground metallic piping systems (water, gas, conduits, petroleum) of a structure?
25 feet
-
What is the common bonding point if the grounded systems (water, gas, electric, communications) are interconnected at a common accessible point in the structure?
- A ground bar
- A section of water pepe OR
- The metallic structural frame
-
Metal bodies located outside or inside the structure that contribute to lightning hazards shall be what?
interconnected with the lightning protection system
-
What is potential equalization?
the bonding together of grounded systems at different building height intervals to eliminate side flash
-
Structures exceeding 60 feet in height need what three potential equalizations?
- Ground-Level
- Roof-Level (12 feet)
- Intermediate-Level
-
Structures up to 60 feet in heigh need what two potential equalizations?
- Ground-level
- Roof-level (7 feet)
-
How small can ground loop conductors be?
no smaller than main lightning conductor
-
Should SPDs be grounded through a lightning protection down conductor?
No
-
Where are SPDs installed?
All power service entrances
-
What dp SPDs need to be in compliance with?
UL 1449 Edition 3
-
What is the nominal discharge rating of SPDs for branch panels or subpanels? AND is for signal data or communication systems?
-
What is the nominal discharge rating of SPDS for supplementary protection?
-
What is the nominal discharge rating of SPDS for service entrances?
-
-
-
-
-
What shall surge protection be provided for?
- Conductive signal
- data
- communication lines
-
What three things should be considered when selecting SPDs?
- frequency
- bandwidth
- voltage
-
What shall SPDs for data and signal line protection have?
common mode protection
-
When installing strike termination devices on structural steel what are the intervals?
air terminals are connected to the metal framework at intervals not exceeding an average distance of 100 feet and are to be as widely spaced as possible.
-
When fastening conductor to a metallic column what is the diameter and how many threads need to be fully engaged?
- no less than 1/2 inch in diameter
- at least 5 threads fully engaged
-
When installing ground electrodes that are connected to metallic columns, how are they installed?
around the perimeter of the structure at intervals averaging not more than 60 feet apart.
-
What can be used for protecting down conductors from mechanical damage?
- wood
- plastic (PVC)
- metal laid over the conductor
-
When does the zone of protection arc change to 100 feet?
- Flammable materials
- Ammunition
- Masts (2 or more)
-
How far away do silos and storage tanks have to be to be classified as standing alone?
6 feet
-
What determines an adjacent storage structure?
if it is 6 feet or less away from the main building but not attached
-
How tall is a heavy duty stack and what is the single cross-sectional flue area?
- more than 75 feet
- flue area exceeds 500 square inches
-
What class materials should heavy duty stacks have?
Class II
-
The upper 25 feet of a heavy duty stack shall have what?
a continuous covering of lead
-
What are the intervals of air termainls on the rim of stacks?
not exceeding 8 feet
-
How far shall air terminals extend above the heavy duty stack?
> 18 inches <30 inches
-
On heavy duty stacks how far above earth are down conductors to be protected from damage?
At least 8 feet
-
If ground rods are used for a heavy duty stack what is the diameter and length?
5/8 inch and 10 feet long
-
How far away does a metal water pipe system have to be to be bonded with the LPS of a stack?
within 25'
-
How far away do trunks of trees have to be from a structure to provide lightning protection?
within 10 feet
-
What are the three design concerns as it relates to open shelters?
- Step potential
- Touch potential
- Sideflash (to person/animal)
-
When protecting an open structure how many down conductors should there be?
a down conductor for every corner
-
How shall clamps be secured to ground rods and down conductors?
- Make contact for 1 1/2 inches
- Secured with at least two bolts
-
When should connections to ground electrodes be made?
- Not less than 1 foot below grade
- Not less than 2 feet away from the foundation wall
-
How far shall ground rods be extended vertically?
not less than 10 feet
-
What are the three things ground rods can be made of?
- Cooper-clad steel
- Solid Copper
- Stainless Steel (corrosive)
-
Masonry anchors are
1/4" diameter
-
What type of metal body must always be considered for bonding?
non-isolated metal body
-
How thick must metal be to be used as an air terminal or main cable conductor?
At least 3/16" thick
-
What is the minimum thickness and surface area of a ground plate?
0.032 inches thick and 2 square feet
-
What are the three approved materials for lightning protection?
- Copper
- Copper Alloys
- Aluminum
-
Nickel is compatible with?
Copper
-
Brass is compatible with?
Copper
-
Tin is compatible with?
Copper
-
Lead is compatible with?
Copper and Aluminum
-
Stainless Steel is compatible with?
Copper and Aluminum
-
Monel is compatible with?
Copper
-
Magnesium is compatible with?
Aluminum
-
Zinc is compatible with?
Aluminum
-
Galvanized Steel is compatible with?
Aluminum
-
Wrought Iron is compatible with?
Aluminum
-
Galvalume is compatible with?
Aluminum
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Bonding
An electrical connection between an electrically conductive object and a component of a lightning protection system that is intended to significantly reduce potential differences created by lightning currents.
-
Bonding Conductor
A conductor used for potential equalization between grounded metal bodies or electrically conductive objects and a lightning protection system. The bonding conductors are normally smaller in size than current carrying conductors.
-
Catenary Lightning Protection System
A lightning protection system consisting of one or more overhead ground wires. (also known as overhead shielding)
-
Combination Waveform Generator
A surge generator with a 2 ohm internal impedance producing a 1.2/50 us open circuit voltage and an 8/20 short-circuit current wave shape.
-
Copper-clad Steel
Steel rod or wire with a coating of copper bonded it.
-
Grounded
Connected to earth or to some conducting body that is connected to earth ground.
-
Heavy Duty Stack
A smoke or vent stack with a flue that has a cross-sectional area greater than 500 square inches and a height greater than 75 feet.
-
MCOV
Maximum Continuous Operating Voltage
-
Maximum Continuous Operating Voltage
The maximum designated rms value of the power frequency voltage that can be continuously applied to the mode of protection of a surge protection device.
-
Maximum Discharge Current
The maximum instantaneous value of the current through the SPD having a 8/20 us waveform.
-
lmax
Maxium Discharge Current
-
MLV
Measure Limiting Voltage
-
ln
Nominal Discharge Current
-
Nominal Discharge Current
Peak value of 8/20 us current waveform selected by the manufacturer for which an SPD remains functional after 15 surges.
-
Nominal System Voltage
The nominal voltage (rms) of the power frequency supply.
-
Normal Operating Voltage
The normal ac power frequency voltage rating, as specified by the manufacturer, to which the surge protection device may be connected.
-
TOV
Temporary Over Voltage
-
Transient
a subcycle disturbance in the ac waveform that is evidenced by a sharp, brief discontinuity of the waveform. It may be of either polarity and may be additive to, or subtractive from the nominal waveform.
-
VPR
Voltage Protection Rating
-
Voltage Protection Rating
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 cicuit voltage of 6kV and a shortcircuit current of 3 kA. The value is rounded up to the next highest 100 V level.
-
Combination Waveform Generator
A surge gnerator with 2-ohm internal impedance producing a 1.2/50 us open circuit voltage and an 8/20 us short-circuit current wave shape.
-
Lightning Electromagnetic Impulse (LEMP)
Electromagnetic effects of lightning current, which includes conducted surges as well as radiated impulse electromagnetic field effects.
-
Transient
A subcycle disturbance in teh ac waveform that is evidenced by a sharp, brief discontinuity of the waveform. It can be of either polarity and can be additive to, or subtractive from, the nominal waveform.
-
Maximum Continuous Operating Voltage (MCOV)
The maximum designated rms value of the power frequency voltage that can be continuously applied to the mode of protection of a surge protection device.
-
Measured Limiting Voltage (MLV)
Maximum magnitude of voltage that is measured across the terminals of the surge protection device during hte application of impulses of specified waveshape and amplitude.
-
Nominal System Voltage
The nominal voltage (RMS) of the power frequency supply.
-
Normal Operating Voltage
The normal ac power frequency voltage rating, as specified by the manufacturer, to which the SPD may be connected.
-
Voltage Protection Rating (VPR)
A rating 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 shortcircuit curret of 3 kA. The value is rounded up to the next highest 100 V level.
-
Zone of Protection Equation
-
-
What are you calculating when you use the Zone of Protection equation? (i.e. what is d?)
horizontal protected distance
-
What is h1 of the protected distance equation for zone of protection?
height of the higher air terminal or protected roof
-
What is h2 of the protected distance equation for zone of protection?
height of the lower roof or object under consideration for protection
-
What is R of the protected distance equation for zone of protection?
rolling sphere radius = 150 feet
-
What is h in the bonding distance formula?
vertical distance between the bond being considered and the nearest lightning protection system bond (for buildings under 40 feet it can be considered the building height)
-
What is n?
- n = 1 where there is only one
- n = 1.5 where there are only two
- n = 2.25 where are are three or more
-
What is Km in the bonding distance formula?
- a value of 1 if the potential flashover is through the air
- a value of 0.50 if through solid building material
-
Sideflash distance from a mast formula
-
What is the equation for sideflash distance from an overhead ground wire?
-
-
Class I - What is the cir. mils of the cross-section area of main conductor cable:
Copper?
Aluminum?
Copper 57,400 cir. mils
Aluminum 98,600 cir. mils
-
Class I - What is the cir. mils of the cross-section area of bonding conductor cable:
Copper?
Aluminum
Copper 26,240 cir. mils
Aluminum 41,100 cir. mils
-
Class I - What is the thickness of solid strip main conductor
Copper?
Aluminum?
Copper 0.051 in.
Aluminum 0.064 in.
-
-
Class II. What is the main conductor cable cross-section area for
Copper?
Aluminum?
Copper 115,000 cir. mils
Aluminum 192,000 cir. mils
-
Class II. What is the bonding conductor cable cross-section area for
Copper?
Aluminum?
Copper 26,240 cir. mils
Aluminum 41,100 cir. mils
-
How are pitched roofs defined?
If the span is 40' or less and a slope of 1/8 or greater
or
if the span is more than 40' and a slope 1/4 or greater.
-
What shall be of 96% conductivity when annealed?
Copper
4.2.2.1
-
How can Aluminum be used?
- 1. Aluminum can be used as long as there is no contact with the earth or the possibility of rapid deterioration.
- 2. Aluminum must be electrical-grade aluminum.
- 3. Aluminum will not come into contact with copper materials.
- 4.2.2.3
-
Where does bonding need to take place where metal pipe or tubing is used around the conductor?
The top and the bottom shall be bonded to the pipe or tubing.
4.4.2
-
Aluminium materials shall not be used with how many inches of contact with the earth?
18"
-
Class II conductors from the higher portion
|
|
