Lightning Protection Flashcards
The third part of the lightning protection system disperses the lightning strike safely into the earth. Which of the following materials are used for the third part of the lightning protection system?
Ground Rings
Ground Rod Electrodes
and Radials
Class II materials are used on structures that exceed ? in height. They are generally larger or heavier than Class I materials.
75’
Copper materials are made from the same grade of copper as ones used for commercial electrical work; these are generally designed to be ? conductive when annealed.
95%
The minimum diameter of a Class I solid copper air terminal is ? .
3/8”
The minimum requirements for a Class I aluminum main lightning conductor are ? strand size, 95 pounds/1,000 feet weight per length, and a cross-sectional area of 98,600 circular mils.
14 AWG
When transitioning from aluminum to copper, fittings must be of the ? type.
bi-metallic
Bimetallic connectors cannot be used within ? of the earth’s surface.
18”
A conductor that encircles a structure that is in direct contact with the earth is called a ? .
Ground Ring Electrode
Ground rods must be driven to a depth of not less than ? into the earth.
10’
An electrical connection between an electrically conductive object and a component of a lightning protection system that is intended to reduce potential differences created by lightning currents is an example of bonding.
True
Down conductors can be either Class I or Class II copper or aluminum lightning conductors (depending on the height of the structure) or structural steel that is at least ? thick.
3/16”
All structures require at least two down conductors and at least one additional down conductor for every ? of roof perimeter over 250 feet.
100’
Aluminum down conductors must transition to copper at a minimum of ? above where they come in contact with the earth, using a listed bimetallic connector.
18”
It is permissible to install down conductors in gutters and downspouts; in fact, this is a good way to hide them.
False
Aluminum conductors must not be installed in concrete or masonry; the alkali content of concrete would rapidly corrode aluminum.
True
The space adjacent to a lightning protection system that is protected from a direct lightning strike is called the ? .
Zone of Protection
Electrically continuous structural steel may be used as a strike termination device or main lightning protection conductor if it is at least ? thick.
3/16”
Air terminals must be placed at or within ? of ridge ends on pitched roofs or at the edges and outside corners of flat or gently sloping roofs.
2’
Air terminals that extend 24 inches or more above the object or area to be protected will be permitted to be placed at intervals not exceeding ? .
25’
If the lightning conductor is run in metal conduit, it must be bonded to the conduit at ? .
- Any point where the conduit is not electrically continuous
- Both Ends
Lightning conductors and all other lightning protection components concealed in steel reinforced concrete must be connected to the reinforcing steel at ? .
- The Lower Extremities
- The Upper Extremities
Horizontal lightning conductor runs must be connected to the reinforcing steel at intervals not exceeding ? .
100’
Grounded and ungrounded metal bodies exceeding ? in vertical length must be bonded to structural steel members as near as is practical to their extremities unless inherently bonded through construction at these locations.
60’
The surge protection requirements outlined in NFPA 780 include both permanently installed and plug-in SPDs.
False
Surge protective devices must be installed at all power service entrances.
True
Surge protective devices must be installed at all points where an electrical or electronic system conductor leaves a structure to supply another structure if the conductors or cable are run over ?
100’
Surge protective devices installed at the service entrance must have a minimum (Imax) rating of ? 8/20 per phase or a nominal discharge current (In) rating of ? 8/20 per phase.
40 kA / 20 kA
