South Carolina Lightning Protection Systems Contractor Examination

Per NFPA 780 (2020), Class I lightning-protection materials are required on ordinary structures of what maximum height?

• A50 ft (15 m)
• B75 ft (23 m)
• C100 ft (30 m)
• D150 ft (46 m)

What is the minimum cross-sectional area of a Class I main copper lightning conductor in NFPA 780 (2020)?

• A41,740 circular mils
• B52,620 circular mils
• C57,400 circular mils
• D115,000 circular mils

What is the minimum cross-sectional area of a Class I main aluminum lightning conductor in NFPA 780 (2020)?

• A57,400 circular mils
• B66,360 circular mils
• C98,600 circular mils
• D115,000 circular mils

What is the minimum cross-sectional area of a Class II main copper lightning conductor in NFPA 780 (2020)?

• A57,400 circular mils
• B83,690 circular mils
• C105,600 circular mils
• D115,000 circular mils

What is the minimum diameter of a solid Class I copper air terminal in NFPA 780 (2020)?

• A1/4 in (6.4 mm)
• B3/8 in (9.5 mm)
• C1/2 in (12.7 mm)
• D5/8 in (15.9 mm)

What is the minimum diameter of a solid Class II copper air terminal in NFPA 780 (2020)?

• A3/8 in (9.5 mm)
• B1/2 in (12.7 mm)
• C5/8 in (15.9 mm)
• D3/4 in (19.1 mm)

What is the minimum diameter of a solid Class I aluminum air terminal in NFPA 780 (2020)?

• A3/8 in (9.5 mm)
• B1/2 in (12.7 mm)
• C5/8 in (15.9 mm)
• D3/4 in (19.1 mm)

A Class I main copper conductor must have at least 57,400 circular mils. What is the smallest standard AWG size that meets that NFPA 780 (2020) area?

• A4 AWG (41,740 CM)
• B3 AWG (52,620 CM)
• C2 AWG (66,360 CM)
• D1 AWG (83,690 CM)

What is the minimum weight of a Class I main copper lightning conductor per 1,000 ft in NFPA 780 (2020)?

• A95 lb per 1,000 ft
• B187 lb per 1,000 ft
• C250 lb per 1,000 ft
• D375 lb per 1,000 ft

An ordinary commercial building in South Carolina measures 80 ft from grade to the highest roof. Which NFPA 780 (2020) material class is required?

• AClass I only, because the building is under 100 ft
• BClass II materials for the entire lightning protection system
• CClass I on the roof and Class II only on down conductors
• DEither class, at the installer's option

Per NFPA 780 (2020) 4.6.2, the tip of an air terminal shall be not less than how far above the object or area it is intended to protect?

• A6 in (150 mm)
• B8 in (200 mm)
• C10 in (254 mm)
• D24 in (610 mm)

What is the maximum spacing along a roof ridge or perimeter for standard air terminals 24 in or less in height under NFPA 780 (2020)?

• A10 ft (3.0 m)
• B20 ft (6.1 m)
• C25 ft (7.6 m)
• D50 ft (15.2 m)

When air terminals taller than 24 in (610 mm) are used, NFPA 780 (2020) permits perimeter or ridge spacing up to which maximum, provided the rod is supported at not less than one-half its height?

• A20 ft (6.1 m)
• B25 ft (7.6 m)
• C30 ft (9.1 m)
• D50 ft (15.2 m)

Strike-termination devices shall be located at or within what distance of ridge ends, outside corners, and roof edges per NFPA 780 (2020)?

• A6 in (150 mm)
• B12 in (300 mm)
• C24 in (610 mm)
• D48 in (1.2 m)

On a flat or gently sloping roof, no point on the roof shall be more than what distance from the nearest strike-termination device under NFPA 780 (2020)?

• A20 ft (6.1 m)
• B25 ft (7.6 m)
• C40 ft (12.2 m)
• D50 ft (15.2 m)

An air terminal 36 in tall is installed on a Class I roof ridge. In addition to the 25 ft spacing allowance, where must that rod be supported?

• AOnly at the base; no intermediate support is required under 48 in
• BAt a point not less than one-half the height of the air terminal
• CAt a point not less than one-third the height of the air terminal
• DContinuously along its full length with a rigid sleeve

A rooftop metal body may be used as a strike-termination device without a dedicated air terminal when it is electrically continuous and has a metal thickness of not less than which value?

• A1/16 in (1.6 mm)
• B1/8 in (3.2 mm)
• C3/16 in (4.8 mm)
• D1/4 in (6.4 mm)

A straight roof ridge is 80 ft long. Using 24 in Class I air terminals, terminals must be within 2 ft of each end and spaced not more than 20 ft apart. What is the minimum number of air terminals required on that ridge?

• A3
• B4
• C5
• D6

What rolling-sphere radius does NFPA 780 (2020) use to define the ordinary-structure zone of protection?

• A50 ft (15 m)
• B100 ft (30 m)
• C150 ft (46 m)
• D300 ft (91 m)

Using the NFPA 780 (2020) 150 ft rolling-sphere model, what is the horizontal protected distance at grade from a 30 ft-high strike-termination device? Use d = √[h(2R − h)], where R = 150 ft.

• A60 ft
• B75 ft
• C90 ft
• D120 ft

NFPA 780 (2020) 4.8.1 permits the protective-angle method with one angle from grade to 25 ft and another from 25 ft to 50 ft. Which method must be used to evaluate protection of surfaces more than 50 ft below the strike-termination device?

• AThe 45-degree cone method only
• BThe placement (layout) method only
• CThe 150 ft rolling-sphere method
• DA single 63-degree angle from the tip to grade

Each strike-termination device shall have a minimum of how many paths to ground in an NFPA 780 (2020) ordinary-structure system?

• AOne dedicated down conductor
• BTwo paths to ground
• CThree paths if the roof is flat
• DFour paths forming a closed loop

What is the minimum number of down conductors required on any ordinary structure protected to NFPA 780 (2020)?

• AOne
• BTwo
• CThree
• DFour

Down conductors shall be spaced at intervals averaging not more than which distance around the structure perimeter?

• A50 ft (15 m)
• B75 ft (23 m)
• C100 ft (30 m)
• D150 ft (46 m)

Structures exceeding which perimeter must have a down conductor for every 100 ft of perimeter or fraction thereof?

• A100 ft (30 m)
• B150 ft (46 m)
• C200 ft (61 m)
• D250 ft (76 m)

No bend of a lightning conductor shall form an included angle of less than which value?

• A45 degrees
• B60 degrees
• C90 degrees
• D120 degrees

What is the minimum bend radius permitted for lightning conductors in NFPA 780 (2020)?

• A4 in (100 mm)
• B6 in (150 mm)
• C8 in (200 mm)
• D12 in (300 mm)

Lightning conductors shall be fastened at intervals not exceeding which distance?

• A18 in (460 mm)
• B3 ft (0.9 m)
• C5 ft (1.5 m)
• D10 ft (3.0 m)

A rectangular building has a protected perimeter of 360 ft. What is the minimum number of down conductors required by NFPA 780 (2020)?

• A2
• B3
• C4
• D5

A 40 ft by 40 ft one-story shop has a 160 ft perimeter. What is the minimum number of down conductors required?

• A1
• B2
• C3
• D4

A 90 ft by 60 ft warehouse has a 300 ft perimeter. What is the minimum number of down conductors required by NFPA 780 (2020)?

• A2
• B3
• C4
• D6

Where should the two or more required down conductors be located on an ordinary structure?

• AGrouped on the same wall to shorten the grounding electrode run
• BAs widely separated as practicable
• COnly at the service-entrance wall
• DOnly at inside corners where the conductor is protected

Why does NFPA 780 require bonding of grounded metal bodies that lie within the calculated bonding distance of a lightning conductor?

• ATo use the metal body as an additional air terminal
• BTo prevent sideflash by equalizing potential during a stroke
• CTo reduce the required number of down conductors
• DTo satisfy NEC ampacity of the metal body

NFPA 780 (2020) calculates bonding distance with which formula?

• AD = 6n / (h × Km)
• BD = (h / 6n) × Km
• CD = (6h / n) × Km
• DD = h × 6n × Km

In the NFPA 780 bonding-distance formula, what value of n is used when only one down conductor lies within a 100 ft (30 m) radius of the metal body?

• A0.50
• B1
• C1.5
• D2.25

A grounded rooftop pipe is 30 ft above the nearest lightning-protection ground reference. There is one down conductor in the 100 ft zone and the flashover path is through air (Km = 1). What is the calculated bonding distance D?

• A2.5 ft
• B5.0 ft
• C7.5 ft
• D30 ft

A grounded metal body is 36 ft above the nearest lightning-protection ground reference. Two down conductors at least 25 ft apart lie in the 100 ft zone, and the path is through air (Km = 1). What is D?

• A2.0 ft
• B4.0 ft
• C6.0 ft
• D9.0 ft

A rooftop HVAC unit is 4.0 ft from a down conductor. The unit is 30 ft above the lightning-protection ground reference, two qualifying downs are in the zone (n = 1.5), and the gap is through air (Km = 1). Is a bond required?

• AYes, because all rooftop HVAC must be bonded regardless of distance
• BYes, because 4.0 ft is less than D = 5.0 ft using n = 1
• CNo, because D = 30 / 9 = 3.33 ft and 4.0 ft is outside that distance
• DNo, because HVAC equipment is isolated by its electrical grounding conductor

In the bonding-distance formula, what value of Km is used when the potential flashover path is through solid building material such as concrete, brick, or wood?

• A0.25
• B0.50
• C1.00
• D2.00

What value of n is used when three or more down conductors, each spaced at least 25 ft (7.6 m) apart, lie within a 100 ft (30 m) radius of the metal body?

• A1
• B1.5
• C2.25
• D3

A grounded steel column is 24 ft above the lightning-protection ground reference. One down conductor is in the zone and the path is through masonry (Km = 0.50). What is D?

• A1.0 ft
• B2.0 ft
• C4.0 ft
• D8.0 ft

Bonding plates used to connect a lightning conductor to a metal body shall have a minimum surface contact area of which value?

• A3 in² (1,900 mm²)
• B4 in² (2,600 mm²)
• C8 in² (5,200 mm²)
• D16 in² (10,300 mm²)

Which of the following grounded systems must be interconnected to the lightning protection system with main-size conductors?

• AOnly the structural steel, if the building is over 75 ft
• BMetallic water piping, electric service grounding, communications grounds, and other larg…
• COnly isolated (ungrounded) rooftop metal bodies
• DOnly the interior isolated grounding bus of sensitive electronics

How does NFPA 780 (2020) define a grounded (non-isolated) metal body?

• AAny metal painted with a conductive coating
• BA metal body that has a ground path independent of the lightning protection system
• COnly metal that is 3/16 in thick or greater
• DOnly metal that is connected to an air terminal

What is the minimum diameter of a ground rod used as an NFPA 780 (2020) lightning-protection grounding electrode?

• A3/8 in (9.5 mm)
• B1/2 in (12.7 mm)
• C5/8 in (15.9 mm)
• D3/4 in (19.1 mm)

An NFPA 780 (2020) ground rod shall extend vertically not less than how far into the earth?

• A6 ft (1.8 m)
• B8 ft (2.4 m)
• C10 ft (3.0 m)
• D20 ft (6.1 m)

What is the minimum manufactured length of an NFPA 780 (2020) ground rod?

• A6 ft (1.8 m)
• B8 ft (2.4 m)
• C10 ft (3.0 m)
• D12 ft (3.7 m)