Lightning Protection System—Quality Installation and Maintenance

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For Reference of NECA 2015 San Francisco Attendees Only 1

Lightning Protection System—Quality Installation and Maintenance

Lightning Protection System—Quality Installation and Maintenance

Michael J. JohnstonNECA Executive Director Standards & Safety

Mark S. HargerPresident/CEO Harger Lightning & Grounding

This session is eligible for 1 Continuing Education Hour

and 1 Contact Hour.

To earn these hours you must:– Have your badge scanned at the door– Attend 90% of this presentation– Fill out the online evaluation for this session

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Why

• There is no ANSI accredited lightning protection standard that addresses best practices

• Less than 2% of all UL Master Label installations get re-inspected after the 5 year date

• Most lightning protection systems on structures are not being maintained

Outline1.0 Scope2.0 Definitions3.0 Design Procedures4.0 Installation5.0 Acquisition of Master Label® Certificate6.0 Inspection, Maintenance and Ground Testing Procedures7.0 Project Management Procedures

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1.0 - Scope

• To provide a “Best Practices” Lightning Protection System Installation Standard that ensures the completed installation complies with the requirements of NFPA® 780, Standard for the Installation of Lightning Protection Systems.

• This standard will cover both new and existing structures.

2.0 - Definitions

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Definitions

ANSI-A United States standards organization responsible for promoting and facilitating voluntary consensus standards and safeguarding their integrity.

Definitions

Down Conductor-A main conductor that carries lightning currents from the top of the structure to the grounding electrodes.

Down ConductorDown Conductor

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DefinitionsExothermic-

A process that produces a welded connection between a conductor and other objects.

DefinitionsGround Access Well-

A protective enclosure which allows the ability to inspect and test individual grounding electrodes or the grounding electrode system.

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DefinitionsNFPA 780-

An ANSI recognized installation standard for lightning protection systems.

DefinitionsRoof Conductor-

A main conductor located at the roof level that interconnects strike termination devices to down conductors.

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DefinitionsThru-Roof-

A connection device that assists in creating a water tight seal when penetrating a roof.

DefinitionsThru-Wall-

A connection device that assists in creating a water tight seal when penetrating a wall.

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3.0 - Design Procedures

• The lightning protection design shall be in accordance with the requirements of NFPA 780, standard for the insulation of lightning protection systems.

Design Procedures

The company providing the design should have a minimum of 5 years experience and be well versed with NFPA 780.

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Design ProceduresExample of a proper lightning protection shop drawing.

Design ProceduresExample of a proper lightning protection shop drawing details.

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Design ProceduresGenerally, it is not advisable to rely on the lightning protection design information provided with the original plans as shown by this example.

Design ProceduresThis is an example of a lightning protection drawing designed to meet the requirements of NFPA 780.

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Design Procedures• Lightning protection systems are designed

specifically for the building or structures they are intended to protect.

Design ProceduresThe design is not only impacted by the shape and size, but also by building systems and structural components.

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4.0 - Installation

• The installation shall be in accordance with the requirements set forth in NFPA 780 and installed in a neat and workmanlike manner

4.1 Pre-Construction Site Assessment

• When: Once the submittal drawings have been approved and before construction begins

• Why: To review important aspects of the installation

• Who: Owner representativeSupervisorRoofing contractorElectrical contractor

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Pre-Construction Site Assessment

• Items to be discussed• Location and placement of ground

electrodes and down conductors• Responsibility for sealing thru-roof

penetrations• Installation of adhesive mounting pads (if

required)

4.2 Ground Electrode Installation and Common Bonding

• Ground electrodes shall be installed in accordance with NFPA 780.

• Common bonding between all building electrode systems shall be installed in accordance with NFPA 780 and NEC 70.

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Ground Electrode Installation

• For testing and maintenance, access of each ground electrode should be available.


• Ground rods should be driven far enough away from the footing and drain tile and also past the roof’s drip edge.

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• Ground rods shall be installed into undisturbed soil.

• If it is not practical to install ground rods outside of the building, the ground rods should be installed as close to the building’s walls as practical without damaging the footing.


The correct ground rod driver adapter should be used to avoid mushrooming or damaging the end of the ground rod.

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If the damage to the ground rod is to severe, the top of the rod may need to be cut off so that the ground rod clamp or exothermic connection can be properly made.

Ground Ring Electrode Installation

If required, a ground ring electrode for the lightning protection system shall be installed at least 18 inches below earth unless prohibited by ground conditions.

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A ground ring electrode installed for the purposes of electrical grounding shall be installed to a depth of at least 30 inches.


• Ground ring electrodes shall be continuous around the structure and connected to all down conductors.

• The ground ring electrode shall be installed below the frost line (if present)

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Common Bonding

• Per NFPA 780, all grounding systems and underground metal piping that enters a building shall be bonded to the lightning protection system within 12 feet of grade level.

Common Bonding

• Other grounding systems to be bonded include but are not limited to;– Electrical service– Communications– Cable television– Antenna systems

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Common Bonding• The use of an intersystem bonding

termination device may help facilitate these connections.

Common Bonding

• A master ground bar is another choice to help facilitate these connections.

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Common Bonding• Buildings exceeding 60 ft. in height, the bonding

connections shall be made to a ground loop conductor.

• A ground ring conductor can serve as a ground loop conductor.

4.3 Down Conductors & Bonding

• When installing, ensure paths for down conductors are clear of obstructions, such as HVAC ducts, large pipes or structural columns or beams.

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Down Conductors

• Lightning conductors must maintain a horizontal or downward path from air terminals to the grounding electrode.

Down Conductors

• Down conductors shall be placed as widely as practicable around the perimeter of the building.

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Down Conductors

• Sharp bends and splices in down conductors should be avoided.

• Bends and splices increase the impedance of the conductor.

Down Conductors• Down conductors shall

be securely fastened to the structure at maximum 3 feet intervals.

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Down Conductors• The conductor clips and hardware must be

the same material as the conductor or a material equally resistant to corrosion.

Down Conductors

• When routing down conductors through exterior walls, a thru-wall device should be used to prevent moisture from entering the structure.

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Down Conductors

• Exposed down conductors in areas subject to physical damage of theft shall be protected with guards or conduits at least 6 feet above grade.

Down Conductors

• Down conductors that are installed in long vertical conduits or raceways should be supported to reduce the strain on the conductor.– Class I conductors should be supported every

100 ft.– Class II conductors should be supported

every 80 ft.

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Down Conductors• Buildings with

electrically continuous structural metal framework, the metal should be used as down conductors.

Down Conductors

• When using the structural metal as a down conductor, the metal shall be cleaned down to base metal, removing all paint, rust, and mill scale to avoid high resistance connections.

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Down Conductors

• When utilizing mechanical connections, antioxidant joint compound should be used to prevent corrosion.

Down Conductors

• Routing down conductors in both new and existing construction may require reestablishing the integrity of fire-rated walls, floors, and ceilings.

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Bonding• Where down conductors

are run on buildings with structural metal framework, each down conductor shall be bonded near the top and bottom.

Bonding

• Steel reinforced concrete columns or CMU walls with reinforcing steel. The rebar shall be bonded at the top and bottom of the down conductors.

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Bonding

• Grounded metal objects near down conductors may require bonding if located within the calculated “side-flash” or bonding distance.

4.4 Thru-Roof Installation

• Installation of thru-roof’s should be reviewed with the roofing contractor, roofing manufacturer, architect and engineer prior to installation.

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Thru-Roof Installation• Thru-roof’s are designed

to accommodate various ranges of roof thickness.

• The thru-roof’s assemblies should be modified at the site so they extend not more than 9 inches above the completed roof.

Thru-Roof Installation

• Thru-roofs should not be installed in low areas of flat or gently sloping roofs.

• On pitched roofs, thru-roofs should not be located in valleys or near gutters.

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4.5 Roof Top Installation

Location & Mounting of Air Terminal Bases• Generally air terminal bases are first to be

mounted to the roof.

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Location & Mounting of Air Terminal Bases

• The layout of air terminal bases typically start in the corner.

• The length of the roof edge or ridge is divided into equal spaces.


• When mounting air terminals near corners and edges, the conductor must maintain at least a minimum 8 inch radius bend.

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• When mounting air terminals on roof-top equipment, make sure that access panels are not obstructed.


• Air terminal bases must be securely attached to the structure with corrosion resistant hardware.

• If adhesive is used, the roofing contractor and manufacturer must be consulted and they must make sure the adhesive is compatible with surface it is to be mounted to.

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Routing of Roof Conductors

• Shop drawings will give the general routing of conductors on the roof.

• The number of splices and connectors may be minimized with some forethought.

• Conductors must be routed to avoid sharp bends of less than 90 degrees or radius bend less than 8 inches.

Routing of Roof Conductors• As with air terminal bases, conductors

should be securely attached to the structure at maximum 3 feet intervals or less in areas where movement of the conductor is of a concern.

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• Conductor that must run through the air for more than 3 feet must be supported.

• Avoid routing conductors perpendicular to the slope of pitched roofs where ice, snow or debris can collect.

Routing of Roof Conductors• Care should be taken when routing conductors to

account for temperature change. Copper and aluminum conductors expand and contract.

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• When routing roof conductors through walls, a thru-wall device should be used to prevent moisture from entering the structure.

4.6 Performance and Quality Control Issues

• Materials used in the installation of a lightning protection system must be listed or labeled by U.L. for use in lightning protection systems.

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Materials

• Although a component may have the UL mark and be listed for the purpose of electrical work, it may not be listed to be used in a lightning protection installation.

Materials

• Lightning protection materials must be compatible with the surfaces to which they are mounted.

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Materials

• Confirm the compatibility of materials when making bonding connections to metal objects.

• Bimetallic connectors may be required.

Materials• Adhesives used must be compatible for

two important reasons.– The adhesive must be compatible with the

surface it is being applied to ensure that it will not destroy the roof membrane or other surfaces.

– Compatibility is important to make sure that the adhesive functions properly and the components are held in place.

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Exothermic Connections

When making exothermic connections, all parts of the connection must be clean and free of moisture before making the connection.

Mold and conductor not properly driedConductor not properly cleaned

5.0 Acquisition of Master Label® Certificate

• A Master Label® Certificate indicates to the building owner that the installed lightning protection system meets the requirements of an installation standard.

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Master Label® Certificate

• A Master Label® Certificate remains valid from the time of inspection until the expiration date unless modifications are made to the structure.

• A Master Label® Certificate expires five years after the inspection date.

Inspection Procedure• The installer is responsible for coordinating

access to all portions of the structure necessary to verify compliance with the specified standard. Some of these areas are;– Main electrical power/distribution room– Main communications room– Service utilities such as sewer, fire suppression,

etc.– Rooftop– Attics– Basements

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Submitting an Application

• Request for inspections shall be done through UL’s web page.

• Submitting on line is a declaration that the installation complies with the applicable requirements.

Post UL Inspection Documents

• Upon successful completion and inspection of the lightning protection system, the Master Label® Certificate will be issued to the building owner and the installation contractor.

• It is the installation contractor’s responsibility to ensure the Master Label® Certificate is published on UL’s public directory.

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6.0 Inspection, Maintenance and Ground Testing Procedures

Inspection and Maintenance• Installations should be inspected upon

completion and shall be required if the Master Label® Certificate is specified.

• A maintenance manual should be provided to the building owner upon completion of the installation.

6.1 Inspection and Maintenance

• Periodic annual inspections are recommended, more frequent inspections may be required based on the following.– Environmental conditions– Classifications of the structure or area

protected– Mounting surface for lightning protection

components.– Lightning protection materials used.

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Inspection and Maintenance

• The lightning protection system should also be inspected whenever any alterations or repairs have been made and if any lightning strikes have known to occur.

• In-depth inspections should be conducted every three to five years.

6.2 Visual Inspections

• Visual inspections are used to determine:– Systems in good operating condition– No loose connections– No components have been compromised– No down conductors have been detached,

severed or stolen

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Visual Inspections

• Visual inspections are also used to determine:– Grounding electrodes are still attached– All conductors, fasteners and other

components are securely attached– No alterations or additions have been made to

the structure– Surge protection devices are still operational.– Lightning protection system is still in

compliance with NFPA 780

• Testing should be done to verify that concealed parts of the system are still electrically continuous as well as to determine if any additional equipotential bonding is needed.

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• Ground resistance testing of the individual grounding electrodes should be conducted to determine if there has been any increase in resistance since the original installation.

6.3 Inspection Guides• An inspection guide should be prepared and made

accessible to the party responsible for the lightning protection system. The following data should be covered.– Overall condition of all lightning protection system

components.– Presence of any corrosion or material wear.– Presence of any loose components.– Resistance measurements of grounding electrodes.– Presence of any new building components– Changes made to the system or structure noted on

the as-built drawings.

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6.4 Maintenance Programs• A maintenance program should contain a

checklist of all items needing inspection including the following:– Inspection of all conductors– Reattach any loose conductors and replace if

needed– Inspect all fittings for tightness and corrosion.– Test and record ground resistance of all

grounding electrodes.– Inspect all surge protection devices– Record any new additions made to the structure

Maintenance Programs

• Complete records should be kept of all maintenance procedures and inspections as they will assist in setting a baseline assessment of the lightning protection system and aid in establishing a preventive maintenance program.

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6.5 Ground Testing

There are two acceptable methods to test the resistance of a grounding electrode.

Three point fall of potential Clamp-on test

Ground Testing

• “Fall of Potential” Method– The grounding electrode system (if multi-

grounded neutral system) and telecommunications ground must be disconnected.

– Individual grounding electrodes must be disconnected from the grounding electrode system and be tested individually to determine the resistance value.

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Ground Testing

• “Clamp-On” Method– The grounding electrode system must be

connected to the electrical power system or a zero reference source.

– Proper placement of the unit is essential in order to obtain a correct reading.

– Grounding electrodes shall be tested individually to determine the resistance value.

7.0 Project Management Procedures

Good project management procedures are essential to the successful design, installation and certification of a lightning protection system.

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Project Management

• Project management begins with proper planning that includes:– Defining the scope of the project– Determining the best work flow– Having procedures in place to deal with§ Communications§ Scope changes§ Quality issues§ Documentation

Project Management

• Project design drawings need to be formalized into complete shop drawings that are coordinated and confirmed by all trade contractors as well as the architect and engineer.

• Approved shop drawings form the basis for the project documentation.

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Project Management

• Determining the best work flow also requires proactive planning.

• Lightning protection systems interact with most other building systems.

• It is important to anticipate installation of other systems so that required connections can be made.

Project Management

• Accurate documentation of the system installation is critically important to certification.

• Procedures must be in place to make certain all concealed portions are accurately documented on as-built drawings as well as with dated photos.

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Questions?

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