1 Scope

NOTE This specification covers the materials, configuration, installation, inspection, and certification of a structural lightning protection system for a building or ordinary structure. (1.1)

1.2 The system shall comply with NFPA 780 and shall be installed so that the completed system intercepts a lightning strike at a preferred termination point, conducts the strike current to earth over a low-impedance path, dissipates the current into the grounding electrode system, and equalizes potential among the metal bodies of the structure so that side flash does not occur.

NOTE A lightning protection system is not a single product but a coordinated assembly of strike-termination devices, conductors, grounding electrodes, bonding connections, and surge protective devices that must function together. (1.3)

NOTE A correctly sized down conductor that terminates on an inadequate ground, or a complete air-terminal network that is not bonded to nearby metal bodies, does not protect the structure. (1.4)

1.5 The Contractor shall treat every requirement of this standard as part of one continuous electrical path from the air terminal to earth.

1.6 The lightning protection grounding electrodes shall be bonded to the building grounding electrode system in accordance with NFPA 780 and NEC 250.106.

NOTE This standard covers the lightning protection system and its dedicated electrodes; the building electrical grounding electrode system, equipment grounding, and bonding of the electrical distribution are covered by Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding. (1.7)

NOTE The two systems are deliberately interconnected so that they rise and fall together in potential during a strike, but their design responsibilities are separate. (1.8)

NOTE Surge protection is addressed by this standard only to the extent of coordinating surge protective devices at the electrical service and at points where conductors enter the structure, because a lightning protection system that diverts a direct strike to earth does nothing to protect against the conducted and induced surges that accompany the event. (1.9)

NOTE Selection and rating of the service-entrance surge protective devices is coordinated with the electrical distribution equipment scope. (1.10)

2 Referenced Standards

2.1 Materials and installation shall comply with the latest adopted edition of the following standards and codes.

Standard	Title
NFPA 780	Standard for the Installation of Lightning Protection Systems
NFPA 70	National Electrical Code
UL 96	Lightning Protection Components
UL 96A	Installation Requirements for Lightning Protection Systems
UL 1449	Surge Protective Devices
UL 467	Grounding and Bonding Equipment
LPI 175	Standard of Practice for the Design, Installation, and Inspection of Lightning Protection Systems
IEEE Std 998	Guide for Direct Lightning Stroke Shielding of Substations
IEEE Std 142	Recommended Practice for Grounding of Industrial and Commercial Power Systems
ASTM B3	Standard Specification for Soft or Annealed Copper Wire

2.2 Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

NOTE NFPA 780 and UL 96A are the two recognized installation standards in the United States, and the 2024 International Building Code accepts compliance with either. (2.3)

NOTE LPI 175 reproduces the NFPA 780 requirements with explanatory material and is the basis for Lightning Protection Institute installer certification. (2.4)

NOTE Where the project pursues a UL Master Label, UL 96A governs the components and field inspection; where the project pursues LPI certification, LPI 175 governs. (2.5)

NOTE IEEE Std 998 is referenced only where shielding-angle or rolling-sphere analysis is performed for tall or open structures and is not a general design basis for ordinary buildings. (2.6)

3 Submittals

3.1 Action Submittals

3.1.1 Contractor shall submit the following for the Engineer's review prior to procurement and installation.

Product data for each component, including air terminals, conductors, fittings, connectors, fasteners, ground rods, and surge protective devices, with the listing mark and listing standard for each
A lightning protection layout drawing showing the air-terminal locations, the main conductor routing along ridges and perimeters, the down-conductor locations and routing, the ground-electrode locations and the ground-ring routing, and every metal body to be bonded
A bonding schedule identifying each metal body within the side-flash distance and the bonding conductor and connector for each
A statement of the system class (Class I or Class II) with the controlling structure height
Manufacturer's installation instructions for connection systems used in concealed or buried locations
A certification plan stating whether a UL Master Label or LPI certification will be provided and the inspection arrangements for each

Action Submittals Requiredcheckbox

☑ Product data with listing marks for all components

☐ Lightning protection layout drawing

☐ Bonding schedule for metal bodies within side-flash distance

☐ System class determination with controlling height

☐ Connection-system installation instructions

☐ Certification plan (UL Master Label or LPI)

3.2 Closeout Submittals

3.2.1 Contractor shall provide the following at substantial completion before the system is accepted.

The UL Master Label certificate, or the LPI Inspection Certificate, for the completed installation
As-built lightning protection drawings reflecting installed terminal locations, conductor routing, electrode locations, and bonding connections
Ground resistance test reports for each lightning protection grounding electrode and for the bonded system
Operation and maintenance data describing inspection intervals and recertification requirements
Surge protective device data with the recorded surge ratings and any event-count or status-indicator baseline readings

Closeout Submittals Requiredcheckbox

☑ UL Master Label certificate or LPI Inspection Certificate

☐ As-built lightning protection drawings

☐ Ground resistance test reports

☐ Operation and maintenance data

☐ Surge protective device data with surge ratings and baseline readings

4 Quality Assurance

4.1 Installer Qualifications

4.1.1 Lightning protection work shall be performed by a contractor regularly engaged in the installation of lightning protection systems and listed by UL or certified by the Lightning Protection Institute.

4.1.2 Where a UL Master Label is required, the installing company shall be a UL Listed lightning protection system installer at the time of installation.

4.1.3 Where LPI certification is required, the work shall be performed under the supervision of an LPI-certified installer or designer.

4.2 Listing and Labeling

4.2.1 All lightning protection components — air terminals, conductors, fittings, connectors, fasteners, bonding devices, and ground rods — shall be listed and labeled to UL 96 by a Nationally Recognized Testing Laboratory.

4.2.2 Components shall be of the class (Class I or Class II) required by the structure height and shall carry the UL mark where a Master Label is pursued, because the Master Label inspection requires that installed materials bear the factory-inspection mark.

4.3 System Certification

System Certificationradio

● UL Master Label certificate

○ LPI Inspection Certificate

○ Both UL Master Label and LPI certification

4.3.1 The completed system shall be inspected and certified by the certifying body before acceptance.

NOTE A UL Master Label is issued only after UL inspects the installation and confirms that it was made by a Listed company, employs marked materials, and complies with UL 96A. (4.3.2)

NOTE An LPI Inspection Certificate similarly confirms compliance with LPI 175 following inspection. (4.3.3)

NOTE The certification establishes that the system, as installed, meets the recognized standard — a requirement that drawings alone cannot satisfy. (4.3.4)

4.4 Regulatory Inspection

4.4.1 Grounding electrodes, the ground ring, and any conductor that will be concealed within construction shall be available for inspection by the Authority Having Jurisdiction and by the certifying body before being concealed by backfill, concrete, or finishes.

4.4.2 The Contractor shall coordinate inspection timing and shall not conceal any portion of the system until it has been inspected and released.

5 Environmental and Service Conditions

NOTE The performance of the grounding portion of the system depends on the soil in which the electrodes are installed, and the durability of the above-grade portion depends on the roof and wall materials it contacts. (5.1)

5.2 Both shall be established before material selection.

5.3 Soil Conditions

Design Soil Condition for Groundingselect

Normal soil (moderate resistivity, frost depth shallow or none)

High-resistivity soil (sand, gravel, or rock near surface)

Corrosive soil (low pH, high chloride or sulfate)

Seasonal freezing with deep frost line

5.3.1 Where soil resistivity is high or the frost line is deep, supplemental grounding measures shall be evaluated in design rather than added as remedial work after construction.

NOTE Extending the ground ring, driving deeper electrodes, increasing the number of electrodes, or applying ground-enhancement material are all far less costly when planned before excavation. (5.3.2)

5.4 Roof and Wall Surface Materials

5.4.1 The roof and wall materials that the system will contact govern the conductor material that may be used, because a galvanic couple between dissimilar metals in the presence of moisture will corrode the less noble metal and eventually break the lightning path.

Predominant Roof Material at Strike-Termination Surfacesselect

Membrane (TPO, EPDM, PVC) over insulation

Built-up or modified bitumen

Standing-seam or corrugated steel

Aluminum roofing or aluminum siding present

Concrete or masonry

6 System Classification

NOTE NFPA 780 establishes two classes of materials based on structure height. (6.1)

NOTE The class determines the minimum conductor size and the minimum dimensions of fittings and terminals throughout the system, because a taller structure subjects the down conductors to greater mechanical and electrical stress. (6.2)

6.3 Class Determination

System Classradio

● Class I (structure not exceeding 75 ft)

○ Class II (structure exceeding 75 ft)

6.3.1 Class I materials shall be used on structures not exceeding 75 ft in height.

6.3.2 Class II materials shall be used on structures exceeding 75 ft in height.

NOTE The controlling height is the height of the structure being protected above grade, not the height of any single appurtenance. (6.3.3)

6.3.4 Where any portion of a structure exceeds 75 ft, Class II materials shall be used for that portion and for the down conductors serving it.

NOTE A Class I system is correct for the large majority of commercial and institutional buildings, which fall below 75 ft. (6.3.5)

6.3.6 The default reflects that majority; the Engineer shall change it to Class II for any structure or portion of a structure that exceeds the height threshold.

7 Air Terminals and Strike Termination

NOTE Air terminals are the strike-termination devices that present a preferred point of attachment for a lightning flash so that the strike contacts the system rather than the structure. (7.1)

NOTE The air terminals, together with the conductors that interconnect them, form the strike-termination network across the top of the structure. (7.2)

7.3 Air Terminal Height

Air Terminal Minimum Height Above Protected Objectselect

10 in (NFPA 780 minimum)

12 in

24 in

7.3.1 The tip of an air terminal shall be not less than 10 in. above the object or area it protects, in accordance with NFPA 780.

7.3.2 A taller terminal increases the zone of protection it provides and may reduce the number of terminals required along a ridge or perimeter; the Engineer shall balance terminal height against wind load and appearance.

7.4 Air Terminal Tip Configuration

Air Terminal Tip Configurationradio

● Blunt tip

○ Pointed tip

NOTE NFPA 780 permits either a sharp or a blunt tip; testing has not demonstrated a meaningful difference in strike-interception performance between the two. (7.4.1)

NOTE A blunt tip is the recommended default because it presents a reduced impalement hazard to personnel who must access the roof for maintenance and is less prone to damage. (7.4.2)

NOTE The choice is a matter of safety and preference, not protection effectiveness. (7.4.3)

7.5 Air Terminal Construction

Air Terminal Typeradio

● Solid rod

○ Tubular

7.5.1 Air terminals shall be solid or tubular and shall meet the minimum cross-section for the system class.

NOTE Solid copper or aluminum rods are the common default for ordinary terminals; tubular terminals are used where a taller terminal is required and weight or wind load favors a hollow section. (7.5.2)

7.5.3 The terminal material shall match the conductor material of the network it serves to avoid a dissimilar-metal connection at the terminal base.

7.6 Air Terminal Spacing

Air Terminal Spacing Along Ridges and Perimetersselect

20 ft (terminals 10 in to under 24 in high)

25 ft (terminals 24 in or higher)

7.6.1 The air-terminal layout shall be as indicated on the lightning protection plan, coordinated with roof penetrations, equipment, and ridge geometry.

7.6.2 Air terminals shall be placed along ridges and around the perimeter of flat or gently sloping roofs at intervals not exceeding 20 ft for terminals not less than 10 in. high.

7.6.3 Where terminals are at least 24 in. high, the spacing interval is permitted to increase to 25 ft.

7.6.4 Terminals shall be located within 2 ft of ridge ends and outside roof corners, because corners and edges are the most probable points of strike attachment.

7.7 Protection of Flat Roof Areas

7.7.1 On a flat roof, areas exceeding 50 ft from the perimeter terminals shall be protected by additional terminals placed on the interior of the roof at intervals not exceeding 50 ft, in accordance with NFPA 780.

NOTE A large flat roof is not protected by perimeter terminals alone, because the interior of the roof lies outside the zone of protection of the edge terminals. (7.7.2)

8 Roof Appurtenances

NOTE Metal and nonmetal objects on the roof require strike termination or bonding depending on their material and dimension. (8.1)

NOTE Rooftop equipment is a frequent point of lightning damage precisely because it projects above the protected plane and is often overlooked in design. (8.2)

8.3 Metal Bodies on the Roof

Rooftop Appurtenance Treatmentcheckbox

☑ Bond metal bodies within side-flash distance to conductor system

☐ Provide dedicated air terminals on tall metal appurtenances

☐ Provide air terminals on nonconductive projections (e.g., plastic vents)

☐ Coordinate with mechanical equipment supports and curbs

8.3.1 A metal body of conductance located on the roof, such as a rooftop unit, exhaust fan, or metal vent, shall be bonded to the lightning protection conductor system where it is within the side-flash distance, and shall be provided with its own air terminal where it projects above the zone of protection.

8.3.2 The Contractor shall not assume that a metal appurtenance protects itself; a metal body that is part of the path can carry strike current into the building unless it is bonded into the external system.

8.4 Nonconductive Projections

8.4.1 A nonconductive projection that extends above the zone of protection, such as a plastic vent or a parapet cap, shall be provided with an air terminal so that the strike terminates on the system rather than on the unprotected object.

8.4.2 The terminal shall be connected to the nearest main conductor.

9 Main and Down Conductors

NOTE The conductors carry strike current from the air terminals to the grounding electrodes. (9.1)

NOTE The main conductor interconnects the air terminals across the roof to form the strike-termination network; the down conductors carry the current from the roof network to earth. (9.2)

9.3 Conductor Class and Size

Main and Down Conductor Classradio

● Class I conductor (structure not exceeding 75 ft)

○ Class II conductor (structure exceeding 75 ft)

9.3.1 Main conductors and down conductors shall meet the minimum cross-section for the system class.

9.3.2 For a Class I copper system, the main conductor shall have a cross-section of not less than 57,400 circular mils; for a Class II copper system, not less than 115,000 circular mils.

9.3.3 Aluminum conductors of the equivalent class shall meet the larger cross-section that NFPA 780 specifies for aluminum.

9.3.4 The Contractor shall not substitute a building electrical grounding conductor for a lightning conductor; the lightning conductor cross-sections are set by the standard for the system class and are not the same as NEC grounding conductor sizes.

9.4 Conductor Form

Conductor Formradio

● Stranded cable

○ Solid strip

NOTE Stranded cable is the common form for both main and down conductors because it tolerates the bends and routing of a roof and wall installation. (9.4.1)

NOTE Solid strip is used where a low-profile run is required on a finished surface. (9.4.2)

9.4.3 Either form shall meet the cross-section required for the class.

9.5 Down Conductor Quantity and Spacing

Down Conductor Average Spacing Around Perimeterrange

ft

506075100

Per drawings

9.5.1 The down-conductor quantity and routing shall be as indicated on the lightning protection plan.

9.5.2 Every structure shall have not fewer than two down conductors, regardless of size, so that there are always at least two paths to earth.

9.5.3 Down conductors shall be spaced around the perimeter of the structure at average intervals not exceeding 100 ft, measured along the protected perimeter, in accordance with NFPA 780.

9.5.4 Irregular structures and structures with projecting wings require additional down conductors so that no point on the perimeter is far from a path to earth.

9.5.5 The 100 ft average is the NFPA 780 maximum; the Engineer may specify closer spacing on tall structures or structures with sensitive contents to divide the strike current among more paths and reduce the current and voltage on any single conductor.

9.6 Conductor Routing and Bends

9.6.1 Conductors shall be routed to maintain a horizontal or downward path toward earth and shall not form a U or a dead end that would require the current to travel upward to continue.

9.6.2 Bends in a conductor shall not be less than an 8 in. radius and shall not turn through more than 90 degrees, in accordance with NFPA 780, because a sharp or reversing bend presents a high impedance that the steeply rising strike current will jump rather than follow.

9.6.3 This single requirement is among the most frequently violated in the field and shall be specifically verified during inspection.

10 Conductor Materials and Dissimilar-Metal Limitations

10.1 Conductor Material

Conductor Materialradio

● Copper

○ Aluminum

NOTE Copper is the default conductor material and is suitable for most installations. (10.1.1)

NOTE Aluminum is used where the system contacts aluminum roofing, aluminum siding, or aluminum coping, because copper must not be installed on or in contact with those aluminum surfaces. (10.1.2)

NOTE The material decision is driven primarily by the surfaces the system contacts, not by cost alone. (10.1.3)

10.2 Dissimilar-Metal Rule

Dissimilar-Metal Transition Methodradio

● Not applicable (single-material system)

○ Bimetallic connector listed for copper-to-aluminum transition

10.2.1 Copper lightning protection materials shall not be installed on, in contact with, or directly above aluminum roofing, siding, coping, or other aluminum surfaces.

10.2.2 Rainwater running off copper carries copper ions that corrode aluminum, so the entire downstream water path, not only the point of contact, shall be considered.

10.2.3 Where the structure has aluminum surfaces in the path, aluminum conductors and fittings shall be used for that portion of the system, and aluminum-to-copper transitions shall be made only with bimetallic connectors listed for the purpose at a location where moisture will not bridge the junction.

10.2.4 Aluminum conductors and fittings shall not be installed within 18 in. of earth and shall not be placed in contact with masonry or concrete where moisture is present, because aluminum corrodes rapidly in those conditions.

10.2.5 The transition from an aluminum above-grade run to the copper grounding connection shall therefore be made above grade with a listed bimetallic fitting, and the buried electrode connection shall be copper.

11 Fasteners and Connectors

11.1 Fasteners

Fastener Spacing (Maximum)select

3 ft (NFPA 780 maximum)

2 ft

11.1.1 Conductors shall be fastened to the structure at intervals not exceeding 3 ft, in accordance with NFPA 780, so that the conductor cannot be displaced by wind or by the mechanical force of the strike current.

11.1.2 Fasteners shall be of a material compatible with both the conductor and the mounting surface to avoid a galvanic couple, and shall be suitable for the roof or wall material to which they attach without compromising its weather integrity.

11.2 Connectors

Connection Method — Concealed or Buriedradio

● Exothermic welded

○ Listed irreversible compression connector

Connection Method — Accessible Locationsselect

Listed mechanical connector

Exothermic welded

Listed irreversible compression connector

11.2.1 Connectors, splices, and bonding fittings shall be listed to UL 96 and shall be of a material compatible with the conductors they join.

11.2.2 Connectors used in contact with earth or concrete shall be additionally listed for direct burial or concrete encasement.

11.2.3 A connector shall maintain its mechanical and electrical integrity under the rapid heating of a strike; connectors not listed for lightning protection use shall not be substituted.

11.2.4 Connections that are buried, encased in concrete, or otherwise inaccessible after construction shall be made by exothermic welding or by a listed irreversible compression connector, so that the connection cannot loosen or corrode at a mechanical interface where it cannot be inspected.

11.2.5 Mechanical bolted connectors shall not be used in inaccessible locations.

12 Grounding Electrodes and Ground Ring

NOTE The grounding electrodes dissipate the strike current into the earth. (12.1)

12.2 Each down conductor shall terminate in a grounding electrode, and the lightning protection grounding shall be coordinated with, and bonded to, the building electrical grounding electrode system per Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

12.3 Grounding Electrode Type

Grounding Electrode Typeselect

Driven ground rod at each down conductor

Ground ring connecting all down conductors

Ground ring with supplemental driven rods

Concrete-encased electrode (where coordinated with foundation)

NOTE A driven ground rod at the base of each down conductor is the basic grounding method and is adequate for most structures in normal soil. (12.3.1)

NOTE A ground ring that interconnects all down conductors equalizes potential among them and is recommended for structures with sensitive contents and for tall structures; it is required by NFPA 780 for certain structures. (12.3.2)

12.3.3 Where a ground ring is provided, it shall encircle the structure in contact with earth and connect to each down conductor and to the building grounding electrode system.

12.4 Driven Rod Electrode

Driven Rod Diameterradio

○ 1/2 in (minimum)

● 5/8 in

○ 3/4 in

12.4.1 A driven rod electrode shall be not less than 1/2 in. in diameter and not less than 8 ft in length, of copper-clad steel, solid copper, or stainless steel, and shall extend vertically not less than 10 ft into the earth where soil conditions permit, in accordance with NFPA 780.

12.4.2 Where rock prevents driving to depth, the alternatives of NFPA 780 — an oblique-driven rod or a buried radial conductor — shall be used.

NOTE A 5/8 in. rod is recommended over the 1/2 in. minimum because the larger diameter resists bending during driving, couples more reliably for sectional rods, and provides greater corrosion margin over the life of the installation. (12.4.3)

12.5 Ground Ring

Ground Ringradio

● Not provided

○ Provided around the structure

12.5.1 The ground ring routing shall be as indicated on the lightning protection and grounding plans.

12.5.2 Where a ground ring is provided, it shall be a conductor of the system class buried in direct contact with earth, encircling the structure, and bonded to every down conductor and to the building grounding electrode system.

12.6 Ground Resistance Target

Maximum Ground Resistance per Electrode Grouprange

ohms

5101525

Per drawings

NOTE NFPA 780 does not set a fixed maximum resistance for lightning grounding, because the function is to dissipate a transient rather than to clear a power fault, but a low and stable resistance reduces the ground potential rise during a strike. (12.6.1)

NOTE A maximum of 10 Ω is a common project target and is the recommended default. (12.6.2)

12.6.3 The Engineer shall set a lower value for structures with sensitive electronics; where the measured value exceeds the target, the Contractor shall add electrodes or extend the ground ring and re-test.

13 Bonding and Potential Equalization

NOTE Bonding ties the metal bodies of the structure to the lightning protection system so that they rise to the same potential during a strike and no destructive side flash jumps between them. (13.1)

NOTE Bonding is what prevents a strike on the external system from arcing through the building to reach a grounded metal body inside. (13.2)

13.3 Side-Flash Distance and Required Bonding

Metal Bodies to be Bondedcheckbox

☑ Rooftop mechanical equipment and metal curbs

☐ Metal roof and wall panels within side-flash distance

☐ Structural steel frame

☐ Metal water, gas, and other piping systems

☐ Metal railings, ladders, and stairs in the lightning path

☐ Antenna and communication masts

13.3.1 Metal bodies of conductance within the calculated side-flash distance of a lightning conductor shall be bonded to the conductor, in accordance with NFPA 780.

13.3.2 The side-flash distance depends on the number of down conductors and the position of the metal body in the system; the Contractor shall calculate it for each metal body and bond every body that falls within the distance.

13.3.3 Metal bodies that intersect the lightning path, such as a metal ladder or a continuous metal wall panel that a down conductor crosses, shall be bonded regardless of the side-flash calculation.

13.4 Bonding to the Building Grounding Electrode System

13.4.1 The lightning protection grounding electrodes shall be bonded to the building grounding electrode system, in accordance with NFPA 780 and NEC 250.106.

NOTE This bond is mandatory and is the single most important interconnection in the installation: without it, a strike raises the lightning ground to a high potential while the electrical ground stays low, and the difference appears across the building wiring and connected equipment. (13.4.2)

13.4.3 The bond shall be made with a conductor of the system class and a listed connector at the grounding electrode system.

13.4.4 Coordinate the connection point with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

13.5 Common Bonding of Grounded Systems

13.5.1 All grounded media entering the structure — the electrical service ground, the metal water service, the metal gas piping, and the telecommunications and antenna grounds — shall be bonded to a common grounding point so that the entire structure operates as a single equipotential reference during a strike.

13.5.2 This common bonding is the practical expression of the principle that there shall be one ground potential, not several isolated ones, throughout the protected structure.

14 Surge Protective Device Coordination

NOTE A lightning protection system diverts a direct strike to earth but does not protect against the conducted surge that travels in on the utility service and the induced surge coupled into building wiring by the strike's electromagnetic field. (14.1)

NOTE Surge protective devices at the points where conductors enter the structure complete the protection and are coordinated with, but not a substitute for, the structural system. (14.2)

14.3 Service-Entrance Surge Protective Device

Service-Entrance SPD Typeradio

● Type 1 (line side of service disconnect)

○ Type 2 (load side of service disconnect)

Service-Entrance SPD Nominal Discharge Current (In)select

10 kA

20 kA

14.3.1 A surge protective device shall be provided at the electrical service entrance, listed to UL 1449 as a Type 1 or Type 2 device, in accordance with NFPA 780 and NEC Article 242.

NOTE A Type 1 device is permitted on the line side of the service disconnect and is the preferred location for the primary service protector because it intercepts the surge before it enters the building distribution. (14.3.2)

14.3.3 The device shall be coordinated with the service equipment scope; selection of the device within the switchboard or switchgear is covered there.

NOTE A nominal discharge current of 20 kA is the recommended default for a service entrance on a structure with a lightning protection system, because a structure worth protecting from a direct strike warrants a service protector sized for the higher surge environment that accompanies one. (14.3.4)

14.4 Surge Protection at Other Conductor Entries

Additional SPD Locationscheckbox

☑ Telecommunications / data service entrance

☐ Antenna and coaxial entries

☐ Critical distribution panels (downstream coordination)

☐ Standby generator and transfer equipment

14.4.1 Surge protective devices shall be provided at the points where signal, data, antenna, and other conductors enter the structure, so that an induced surge on those conductors is diverted to the common ground rather than carried into the connected equipment.

14.4.2 Each such device shall be referenced to the same common grounding point as the lightning and electrical grounds, because a surge protector referenced to a different ground simply moves the surge rather than diverting it.

15 Testing and Inspection

15.1 Visual Inspection

15.1.1 The completed system shall be visually inspected for compliance with the layout drawing and the installation standard before any portion is concealed and again at completion.

15.1.2 The inspection shall confirm air-terminal locations and heights, conductor routing and bend radii, fastener spacing, the presence and integrity of every bonding connection, and the absence of dead ends and reversing bends in the conductor runs.

15.2 Ground Resistance Testing

Ground Resistance Test Methodselect

Fall-of-potential (3-point) method

Clamp-on (induced frequency) method

15.2.1 The resistance to earth of each grounding electrode group and of the bonded system shall be measured after installation.

15.2.2 The test method shall be appropriate to the electrode configuration.

NOTE The fall-of-potential method is the reference method where an electrode can be temporarily isolated. (15.2.3)

15.2.4 The clamp-on method may be used to verify electrodes that have a parallel return path through the bonded system, but it shall not be the sole acceptance test of an isolated electrode.

15.2.5 Where a measured value exceeds the target, the Contractor shall add electrodes or extend the ground ring and re-test until the criterion is met.

15.3 Continuity and Bonding Verification

15.3.1 The Contractor shall verify electrical continuity from representative air terminals through the conductor network to the grounding electrodes.

15.3.2 The Contractor shall verify that each required bond — to rooftop metal bodies, to structural steel, to piping, and to the building grounding electrode system — is present and electrically continuous.

15.4 Certification Inspection

15.4.1 The certifying body shall inspect the completed system and issue the UL Master Label certificate or the LPI Inspection Certificate.

15.4.2 The Contractor shall correct any deficiency identified by the certifying body and shall not request final acceptance until the certificate is issued.

16 Installation

16.1 Concealment

16.1.1 Where conductors are concealed within the construction, they shall be installed before the concealing finish and shall be inspected at each stage before concealment.

16.1.2 Concealed conductors shall maintain the same bend-radius, routing, and fastening requirements as exposed conductors, and their routing shall be recorded on the as-built drawings because they cannot be inspected after completion.

16.2 Masts and Tall Appurtenances

16.2.1 Masts, flagpoles, antennas, and similar tall metal appurtenances that rise above the protected plane shall be either provided with their own air terminal and down conductor or bonded into the system as a strike-termination device in their own right, in accordance with NFPA 780.

16.2.2 A tall metal mast is itself a strike receptor and shall be treated as part of the conductor path, not as an object to be protected by terminals elsewhere on the roof.

16.3 Coordination with Other Trades

16.3.1 The Contractor shall coordinate conductor routing and concealment with the roofing, structural, and electrical trades so that penetrations through the roof membrane are flashed and sealed, conductors do not interfere with roof drainage or equipment access, and the connection to the building grounding electrode system is made at a point agreed with the electrical scope.

16.3.2 Coordinate the grounding interconnection with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding and the service surge protective device with the service equipment scope.

17 Delivery, Storage, and Handling

17.1 Lightning protection materials shall be delivered in the manufacturer's original packaging with listing marks intact, because the UL Master Label inspection requires that installed materials bear the factory-inspection mark.

17.2 Conductors, terminals, and connectors shall be stored indoors in a clean, dry location and protected from corrosive atmospheres and from contact with dissimilar metals until installed.

17.3 Exothermic weld molds and weld material shall be stored dry, because moisture in the mold or charge produces porous, defective welds.

18 Warranty

Installation Warranty Periodselect

1 year from substantial completion

2 years from substantial completion

18.1 Lightning protection components that carry a manufacturer warranty against defects in materials and workmanship shall be warranted to the Owner.

18.2 The Contractor shall warrant the installation, including all connections and the bonding to the building grounding electrode system, for the project warranty period.

NOTE A UL Master Label certificate is issued with a five-year term, after which the system should be re-inspected and a new certificate issued. (18.3)

18.4 The Engineer may require that the warranty obligate the Contractor to support the recertification inspection at the end of the certificate term.

19 Spare Parts

Owner Spare Bonding Materialsradio

● Not provided

○ Provide spare air terminals, bonding connectors, and fittings for future equipment changes

NOTE Spare parts are generally not required for a lightning protection system because it has no operating or wearing components. (19.1)

19.2 Where the Owner maintains rooftop equipment that is frequently relocated, the Owner may stock a small quantity of air terminals, bonding connectors, and conductor fittings of the installed type so that bonding can be restored after equipment is moved without compromising the certification.