### **ITEM L‑108 UNDERGROUND POWER CABLE FOR AIRPORTS**

DESCRIPTION

**108‑1.1** This item shall consist of furnishing and installing power
cables direct buried and furnishing and/or installing power cables
within conduit or duct banks in accordance with these specifications at
the locations shown on the plans. It includes excavation and backfill of
trench for direct-buried cables only. Also included are the installation
of counterpoise wires, ground wires, ground rods and connections, cable
splicing, cable marking, cable testing, and all incidentals necessary to
place the cable in operating condition as a completed unit to the
satisfaction of the Engineer. This item shall not include the
installation of duct banks or conduit, trenching and backfilling for
duct banks or conduit, or furnishing or installation of any cable for
FAA facilities. Requirements and payment for trenching and backfilling
for the installation of underground conduit and duct banks is covered
under Item L-110 "Airport Underground Electrical Duct Banks and
Conduits."

EQUIPMENT AND MATERIALS

**108‑2.1 GENERAL.**

**a.** Airport lighting equipment and materials covered by Federal
Aviation Administration (FAA) specifications shall be approved under the
Airport Lighting Equipment Certification Program described in Advisory
Circular (AC) 150/5345-53, current version.

**b.** All other equipment and materials covered by other referenced
specifications shall be subject to acceptance through manufacturer\'s
certification of compliance with the applicable specification, when
requested by the Engineer.

**c.** Manufacturer\'s certifications shall not relieve the Contractor
of the Contractor's responsibility to provide materials in accordance
with these specifications and acceptable to the Engineer. Materials
supplied and/or installed that do not materially comply with these
specifications shall be removed, when directed by the Engineer and
replaced with materials, which do comply with these specifications, at
the sole cost of the Contractor.

**d.** All materials and equipment used to construct this item shall be
submitted to the Engineer for approval prior to ordering the equipment.
Submittals consisting of marked catalog sheets or shop drawings shall be
provided. Submittal data shall be presented in a clear, precise and
thorough manner. Original catalog sheets are preferred. Photocopies are
acceptable provided they are as good a quality as the original. Clearly
and boldly mark each copy to identify pertinent products or models
applicable to this project. Indicate all optional equipment and delete
non-pertinent data. Submittals for components of electrical equipment
and systems shall identify the equipment for which they apply on each
submittal sheet. Markings shall be boldly and clearly made with arrows
or circles (highlighting is not acceptable). Contractor is solely
responsible for delays in project accruing directly or indirectly from
late submissions or resubmissions of submittals.

**e.** The data submitted shall be sufficient, in the opinion of the
Engineer, to determine compliance with the plans and specifications.
\[The Contractor\'s submittals shall be neatly bound in a properly sized
3-ring binder, tabbed by specification section.\] The Engineer reserves
the right to reject any and all equipment, materials or procedures,
which, in the Engineer's opinion, does not meet the system design and
the standards and codes, specified herein.

**f.** All equipment and materials furnished and installed under this
section shall be guaranteed against defects in materials and workmanship
for a period of at least \[twelve (12) months\] from final acceptance by
the Owner. The defective materials and/or equipment shall be repaired or
replaced, at the Owner\'s discretion, with no additional cost to the
Owner. The Contractor shall be responsible to maintain an insulation
resistance of 50 megohms minima, (1000V megger) with isolation
transformers connected in new circuits and new segments of existing
circuits through the end of the contract warranty period.

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> **The engineer should specify the form in which submittals are to be
> received and number of copies.**
>
> **The length of time for guarantee of materials and workmanship should
> be as stated in the contract between the owner and contractor and the
> contract special provisions.**

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**108‑2.2 CABLE.** Underground cable for airfield lighting facilities
(runway and taxiway lights and signs) shall conform to the requirements
of AC 150/5345‑7, Specification for L‑824 Underground Electrical Cable
for Airport Lighting Circuits. Conductor sizes noted above shall not
apply to leads furnished by manufacturers on airfield lighting
transformers and fixtures.

Wire for electrical circuits up to 600 volts shall comply with
Specification L-824 and/or Federal Specification J-C-30 and shall be
type THWN-2.

Cable type, size, number of conductors, strand and service voltage shall
be as specified on the plans.

**108‑2.3 BARE COPPER WIRE (COUNTERPOISE OR GROUND) AND GROUND RODS.**
Wire for counterpoise or ground installations for airfield lighting
systems shall be No. 6 AWG solid for counterpoise and or No. 6 AWG
stranded for ground wire conforming to ASTM B 3 and ASTM B 8, and shall
be **\[bare copper wire\] \[tinned copper\]** conforming to the
requirements of ASTM D 33.

Ground rods shall be **\[solid stainless steel\] \[copper\] or
\[copper-clad steel\]**. The ground rods shall be of the length and
diameter specified on the plans, but in no case shall they be less than
8‑feet (240 cm) long nor less than 5/8 inch (15 mm) in diameter.

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> **Engineer should evaluate the soils in the vicinity of proposed
> counterpoise and ground rod installations and determine if soil
> conditions would adversely affect copper. Engineer shall specify the
> type of ground rod and counterpoise wire to be installed in
> consideration of the soil conditions. If tinned copper counterpoise or
> ground wire is specified, include requirement for UL listing.**

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**108‑2.4 CABLE CONNECTIONS.** In‑line connections of underground
primary cables shall be of the type called for on the plans, and shall
be one of the types listed below. No separate payment will be made for
cable connections.

**a. The Cast Splice.** A cast splice, employing a plastic mold and
using epoxy resin equivalent to that manufactured by Minnesota Mining
and Manufacturing Company, "Scotchcast" Kit No. 82‑‑B, or as
manufactured by Hysol Corporation, "Hyseal Epoxy Splice" Kit No. E1135,
or equivalent, is used for potting the splice is acceptable.

**b. The Field‑attached Plug‑in Splice.** Figure 3 of AC 150/5345‑26,
Specification for L‑823 Plug and Receptacle, Cable Connectors, employing
connector kits, is acceptable for field attachment to single conductor
cable. It shall be the Contractor's responsibility to determine the
outside diameter of the cable to be spliced and to furnish appropriately
sized connector kits and/or adapters and heat shrink tubing with
integral sealant.

**c. The Factory‑Molded Plug‑in Splice.** Specification for L‑823
Connectors, Factory‑Molded to Individual Conductors, is acceptable.

**d. The Taped or Heat-Shrinked Splice.** Taped splices employing
field‑applied rubber, or synthetic rubber tape covered with plastic tape
is acceptable. The rubber tape should meet the requirements of ASTM D
4388 and the plastic tape should comply with Mil Spec. MIL-I-24391or
Fed. Spec. A-A-55809. Heat shrinkable tubing shall be heavy-wall,
self-sealing tubing rated for the voltage of the wire being spliced and
suitable for direct-buried installations. The tubing shall be factory
coated with a thermoplastic adhesive-sealant that will adhere to the
insulation of the wire being spliced forming a moisture- and dirt-proof
seal. Additionally, heat shrinkable tubing for multi-conductor cables,
shielded cables, and armored cables shall be factory kits designed for
the application. Heat shrinkable tubing and tubing kits shall be
manufactured by Tyco Electronics/ Raychem Corporation, Energy Division,
or approved equivalent.

**e.** In all the above cases, connections of cable conductors shall be
made using crimp connectors utilizing a crimping tool designed to make a
complete crimp before the tool can be removed. All L-823/L-824 splices
and terminations shall be made in accordance with the manufacturer's
recommendations and listings.

**f.** All connections of counterpoise, grounding conductors and ground
rods shall be made by the exothermic process or approved equivalent,
except the base can ground clamp connector shall be used for attachment
to the base can. All exothermic connections shall be made in accordance
with the manufacturer's recommendations and listings.

**108-2.5 SPLICER QUALIFICATIONS.** Every airfield lighting cable
splicer shall be qualified in making cable splices and terminations on
cables rated above 5,000 volts AC. The Contractor shall submit to the
Engineer proof of the qualifications of each proposed cable splicer for
the cable type and voltage level to be worked on. Cable
splicing/terminating personnel shall have a minimum of three (3) years
continuous experience in terminating/splicing medium voltage cable.

**108‑2.6 CONCRETE.** Concrete for cable markers shall conform to
Specification Item P‑610, \`\`Structural Portland Cement Concrete.\'\'

# 

**108-2.7 FLOWABLE BACKFILL.** Flowable material used to backfill
trenches for power cable trenches shall conform to the requirements of
Item P-153 "Controlled Low Strength Material".

**108-2.8 CABLE IDENTIFICATION TAGS.** Cable identification tags shall
by made from a non-corrosive material with the circuit identification
stamped or etched onto the tag. The tags shall be of the type as
detailed on the plans.

**108-2.9 TAPE.** Electrical tapes shall be Scotch Electrical Tapes --
number Scotch 88 (1-1/2" wide) and Scotch 130C linerless rubber splicing
tape (2" wide), as manufactured by the Minnesota Mining and
Manufacturing Company, or approved equivalent.

**108-2.10 ELECTRICAL COATING.** Scotchkote shall be as manufactured by
Minnesota Mining and Manufacturing Company, or approved equivalent.

**108-2.11 EXISTING CIRCUITS.** Whenever the scope of work requires,
connection to an existing circuit, the circuit's insulation resistance
shall be tested, in the presence of the Engineer. The test shall be
performed in accordance with this item and prior to any activity
affecting the respective circuit. The Contractor shall record the
results on forms acceptable to the engineer. When the work affecting the
circuit is complete, the circuit's insulation resistance shall be
checked again, in the presence of the Engineer. The Contractor shall
record the results on forms acceptable to the engineer. The second
reading shall be equal to or greater than the first reading or the
Contractor shall make the necessary repairs to the circuit to bring the
second reading above the first reading. All repair costs including a
complete replacement of the L-823 connectors, L-830 transformers and
L-824 cable, if necessary, shall be borne by the Contractor. All test
results shall be submitted in the Operation and Maintenance (O&M)
Manual.

# 

CONSTRUCTION METHODS

**108‑3.1 GENERAL.** The Contractor shall install the specified cable at
the approximate locations indicated on the plans. Unless otherwise shown
on the plans, all cable required to cross under pavements expected to
carry aircraft loads shall be installed in concrete encased duct banks.
Wherever possible, cable shall be run without splices, from connection
to connection.

Cable connections between lights will be permitted only at the light
locations for connecting the underground cable to the primary leads of
the individual isolation transformers. The Contractor shall be
responsible for providing cable in continuous lengths for home runs or
other long cable runs without connections, unless otherwise authorized
in writing by the Engineer or shown on the plans.

In addition to connectors being installed at individual isolation
transformers, L-823 cable connectors for maintenance and test points
shall be installed at locations shown on the plans. Cable circuit
identification markers shall be installed on both sides of the L-823
connectors installed or at least once in each access point where L-823
connectors are not installed.

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> **Engineer should determine and specify on the plans an adequate
> number of locations for installing L-823 connectors to provide
> maintenance and test points.**

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Provide not less than 3 feet of cable slack on each side of all
connections, isolation transformers, light units, and at points where
cable is connected to field equipment. Where provisions must be made for
testing or for future above grade connections, provide enough slack to
allow the cable to be extended at least one foot vertically above the
top of the access structure. This requirement also applies where primary
cable passes through empty base cans, junction and access structures to
allow for future connections, or as designated by the Engineer.

**108‑3.2 INSTALLATION IN DUCT BANKS OR CONDUITS.** This item includes
the installation of the cable in duct banks or conduit as described
below. The maximum number and voltage ratings of cables installed in
each single duct or conduit, and the current‑carrying capacity of each
cable shall be in accordance with the latest National Electric Code, or
the code of the local agency or authority having jurisdiction.

The Contractor shall make no connections or splices of any kind in
cables installed in conduits or duct banks.

Unless otherwise designated in the plans, where ducts are in tiers, use
the lowest ducts to receive the cable first, with spare ducts left in
the upper levels. Check duct routes prior to construction to obtain
assurance that the shortest routes are selected and interferences are
avoided.

Duct banks or conduits shall be installed as a separate item in
accordance with Item L‑110, \`\`Airport Underground Electrical Duct
Banks and Conduit.\'\' The Contractor shall run a mandrel through duct
banks or conduit prior to installation of cable to insure that the duct
bank or conduit is open, continuous and clear of debris. Mandrel size
shall be compatible with conduit size. The Contractor shall swab out all
conduits/ducts and clean base can, manhole, etc. interiors IMMEDIATELY
prior to pulling cable. Once cleaned and swabbed the base cans and all
accessible points of entry to the duct/conduit system shall be kept
closed except when installing cables. Cleaning of ducts, base cans,
manholes, etc. is incidental to the pay item of the item being cleaned.
All raceway systems left open, after initial cleaning, for any reason
shall be recleaned at the Contractor's expense. All accessible points
shall be kept closed when not installing cable. The Contractor shall
verify existing ducts proposed for use in this project as clear and
open. The Contractor shall notify the Engineer of any blockage in the
existing ducts. The cable shall be installed in a manner to prevent
harmful stretching of the conductor, injury to the insulation, or damage
to the outer protective covering. The ends of all cables shall be sealed
with moisture‑seal tape providing moisture-tight mechanical protection
with minimum bulk, or alternately, heat shrinkable tubing before pulling
into the conduit and it shall be left sealed until connections are made.
Where more than one cable is to be installed in a conduit, all cable
shall be pulled in the conduit at the same time. The pulling of a cable
through duct banks or conduits may be accomplished by handwinch or power
winch with the use of cable grips or pulling eyes. Maximum pulling
tensions shall be governed by cable manufacturer's recommendations. A
non-hardening lubricant recommended for the type of cable being
installed shall be used where pulling lubricant is required.

**\[Contractor shall submit pulling tension values to the Engineer prior
to any cable installation. If required by the Engineer, pulling tension
values for cable pulls shall be monitored by a dynamometer in the
presence of the Engineer. Cable pull tensions shall be recorded by the
Contractor and reviewed by the Engineer. Cables exceeding the maximum
allowable pulling tension values shall be removed and replaced by the
Contractor at the Contractor's expense.\]**

The manufacturer\'s minimum bend radius or the NEC requirements
whichever is more restrictive shall apply. Cable installation, handling
and storage shall be per manufacturer\'s recommendations. During cold
weather, particular attention shall be paid to the manufacturer\'s
minimum installation temperature. Cable shall not be installed when the
temperature is at or below the manufacturer\'s minimum installation
temperature. At the Contractor's option, the Contractor may submit a
plan, for review by the Engineer, for heated storage of the cable and
maintenance of an acceptable cable temperature during installation when
temperatures are below the manufacturer's minimum cable installation
temperature.

Cable shall not be dragged across base can or manhole edges, pavement or
earth. When cable must be coiled, lay cable out on a canvas tarp or
utilize other appropriate means to prevent abrasion to the cable jacket.

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> **Engineer may optionally add this language.**

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**108‑3.3 INSTALLATION OF DIRECT-BURIED CABLE IN TRENCHES.** Unless
otherwise specified, the Contractor shall not use a cable plow for
installing the cable. Cable(s) shall be unreeled uniformly in place
alongside or in the trench and shall be carefully placed along the
bottom of the trench. The cable(s) shall not be unreeled and pulled into
the trench from one end. Slack cable sufficient to provide strain relief
shall be placed in the trench in a series of S curves. Sharp bends or
kinks in the cable shall not be permitted.

Where cables must cross over each other, a minimum of 3‑inch vertical
displacement shall be provided with the topmost cable depth at or below
the minimum required depth below finished grade.

Primary airfield lighting cables installed shall have cable circuit
identification markers attached on both sides of each L-823 connector
and on each airport lighting cable entering or leaving cable access
points, such as manholes, handholes, pullboxes, junction boxes, etc.
Markers shall be of sufficient length for imprinting the cable circuit
identification legend on one line, using letters not less than ¼ inch in
size. The cable circuit identification shall match the circuits noted on
the construction plans.

**a. Trenching.** Where turf is well established and the sod can be
removed, it shall be carefully stripped and properly stored. Trenches
for cables may be excavated manually or with mechanical trenching
equipment. Walls of trenches shall be essentially vertical so that a
minimum of surface is disturbed. Graders shall not be used to excavate
the trench with their blades. The bottom surface of trenches shall be
essentially smooth and free from coarse aggregate. Unless otherwise
specified, cable trenches shall be excavated to a minimum depth of 18
inches below finished grade, except as follows:

> **(1)** When off the airport or crossing under a roadway or driveway,
> the minimum depth shall be 36 inches unless otherwise specified.
>
> **(2)** Minimum cable depth when crossing under a railroad track,
> shall be 42 inches unless otherwise specified.

Dewatering necessary for cable installation, erosion and turbidity
control, in accordance with Federal, State, and Local requirements is
incidental to its respective pay items as part of Item L-108. The cost
of all excavation regardless of type of material encountered, shall be
included in the unit price bid for the L-108 Item.

The Contractor shall excavate all cable trenches to a width not less
than 6 inches. Unless otherwise specified on the plans, all cables in
the same location and running in the same general direction shall be
installed in the same trench.

When rock is encountered, the rock shall be removed to a depth of at
least 3 inches below the required cable depth and it shall be replaced
with bedding material of earth or sand containing no mineral aggregate
particles that would be retained on a 1/4‑inch sieve. Flowable backfill
material may alternatively be used. The Contractor shall ascertain the
type of soil or rock to be excavated before bidding. All such rock
removal shall be performed and paid for under Item P-152.

Duct bank or conduit markers temporarily removed for trench excavations
shall be replaced as required.

It is the Contractor's responsibility to locate existing utilities
within the work area prior to excavation. Where existing active cable(s)
cross proposed installations, the Contractor shall insure that these
cable(s) are adequately protected. Where crossings are unavoidable, no
splices will be allowed in the existing cables, except as specified on
the plans. Installation of new cable where such crossings must occur
shall proceed as follows:

**(1)** Existing cables shall be located manually. Unearthed cables
shall be inspected to assure absolutely no damage has occurred.

**(2)** Trenching, etc., in cable areas shall then proceed, with
approval of the Engineer, with care taken to minimize possible damage or
disruption of existing cable, including careful backfilling in area of
cable.

In the event that any previously identified cable is damaged during the
course of construction, the Contractor shall be responsible for the
complete repair or replacement.

**b. Backfilling.** After the cable has been installed, the trench shall
be backfilled. The first layer of backfill in the trench shall be 3
inches deep, loose measurement, and shall be either earth or sand
containing no mineral aggregate particles that would be retained on a
1/4‑inch sieve. This layer shall not be compacted. The second layer
shall be 5 inches deep, loose measurement, and shall contain no
particles that would be retained on a 1‑inch sieve. The remaining 3^rd^
and subsequent layers of backfill shall not exceed 8 inches of loose
measurement and be excavated or imported material and shall not contain
stone or aggregate larger than 4 inches maximum diameter.

The second and subsequent layers shall be thoroughly tamped and
compacted to at least the density of the adjacent undisturbed soil, and
to the satisfaction of the Engineer. If necessary to obtain the desired
compaction, the backfill material shall be moistened or aerated as
required.

Trenches shall not contain pools of water during backfilling operations.
The trench shall be completely backfilled and tamped level with the
adjacent surface, except that when turf is to be established over the
trench, the backfilling shall be stopped at an appropriate depth
consistent with the type of turfing operation to be accommodated. A
proper allowance for settlement shall also be provided. Any excess
excavated material shall be removed and disposed of in accordance with
the plans and specifications.

Underground electrical warning (caution) tape shall be installed in the
trench above all direct-buried cable. Contractor shall submit a sample
of the proposed warning tape for acceptance by the Engineer. If not
shown on the plans, the warning tape shall be located six inches above
the direct-buried cable or the counterpoise wire if present. A 4-6 inch
wide polyethylene film detectable tape, with a metalized foil core,
shall be installed above all direct buried cable or counterpoise. The
tape shall be of the color and have a continuous legend as indicated on
the plans. The tape shall be installed 8 inches minimum below finished
grade.

**c. Restoration.** Where soil and sod has been removed, it shall be
replaced as soon as possible after the backfilling is completed. All
areas disturbed by work shall be restored to its original condition. The
restoration shall include the **\[sodding\]** **\[topsoiling\]
\[fertilizing\] \[liming\] \[seeding\] \[sprigging\] \[mulching\]** as
shown on the plans. The Contractor shall be held responsible for
maintaining all disturbed surfaces and replacements until final
acceptance. When trenching is through paved areas, restoration shall be
equal to existing conditions and compaction shall meet the requirements
of Item P-152. Restoration shall be considered incidental to the pay
item of which it is a component part.

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> **Engineer to specify the correct method of turfing and remember to
> include in the construction documents the appropriate FAA turfing
> specification for restoration related to the installation of the power
> cables.**

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> **Under certain conditions, it may be beneficial to install cables by
> cable plowing. This type of installation method should only be
> specified where sandy soils are prevalent and with no rocks or other
> debris that would nick or cut the cable insulation. The engineer
> should specify the equipment to be used so the cables are placed at a
> minimum depth of 18 inches below finished grade. The cable should be
> manually unreeled off the spool as the machine travels, such that the
> earth is not unreeling the spool.**

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**108‑3.4 CABLE MARKERS FOR DIRECT-BURIED CABLE.** The location of
direct buried circuits shall be marked by a concrete slab marker, 2 feet
(60 cm) square and 4-6 inches (100-150 mm) thick, extending
approximately 1 inch (25 mm) above the surface. Each cable run from a
line of lights and signs to the equipment vault shall be marked at
approximately every 200 feet (60 m) along the cable run, with an
additional marker at each change of direction of cable run. All other
direct-buried cable shall be marked in the same manner. Cable markers
shall be installed directly above the cable. The Contractor shall
impress the word "CABLE" and directional arrows on each cable marking
slab. The letters shall be approximately 4 inches (100 mm) high and 3
inches (75 mm) wide, with width of stroke 1/2 inch (12 mm) and 1/4 inch
(6 mm) deep.

The location of each underground cable connection, except at lighting
units, or isolation transformers, or power adapters shall be marked by a
concrete marker slab placed above the connection. The Contractor shall
impress the word "SPLICE" on each slab. The Contractor also shall
impress additional circuit identification symbols on each slab as
directed by the Engineer. All cable markers and splice markers shall be
painted international orange. Paint shall be specifically manufactured
for uncured exterior concrete. Furnishing and installation of cable
markers is incidental to the respective cable pay item.

**108‑3.5 SPLICING.** Connections of the type shown on the plans shall
be made by experienced personnel regularly engaged in this type of work
and shall be made as follows:

**a. Cast Splices.** These shall be made by using crimp connectors for
jointing conductors. Molds shall be assembled, and the compound shall be
mixed and poured in accordance with manufacturer\'s instructions and to
the satisfaction of the Engineer.

**b. Field‑attached Plug‑in Splices.** These shall be assembled in
accordance with manufacturer\'s instructions. These splices shall be
made by plugging directly into mating connectors. In all cases the joint
where the connectors come together shall be wrapped with at least one
layer of rubber or synthetic rubber tape and one layer of plastic tape,
one‑half lapped, extending at least 1‑1/2 inches (37 mm) on each side of
the joint.

**c. Factory‑Molded Plug‑in Splices.** These shall be made by plugging
directly into mating connectors. In all cases, the joint where the
connectors come together shall be wrapped with at least one layer of
rubber or synthetic rubber tape and one layer of plastic tape, one‑half
lapped, extending at least 1‑1/2 inches (37 mm) on each side of the
joint.

**d. Taped or Heat-Shrinked Splices.** A taped splice shall be made in
the following manner:

Bring the cables to their final position and cut so that the conductors
will butt. Remove insulation and jacket allowing for bare conductor of
proper length to fit compression sleeve connector with 1/4 inch (6 mm)
of bare conductor on each side of the connector. Prior to splicing, the
two ends of the cable insulation shall be penciled using a tool designed
specifically for this purpose and for cable size and type. Do not use
emery paper on splicing operation since it contains metallic particles.
The copper conductors shall be thoroughly cleaned. Join the conductors
by inserting them equidistant into the compression connection sleeve.
Crimp conductors firmly in place with crimping tool that requires a
complete crimp before tool can be removed. Test the crimped connection
by pulling on the cable. Scrape the insulation to assure that the entire
surface over which the tape will be applied (plus 3 inches (75 mm) on
each end) is clean. After scraping wipe the entire area with a clean
lint‑free cloth. Do not use solvents.

Apply high‑voltage rubber tape one‑half lapped over bare conductor. This
tape should be tensioned as recommended by the manufacturer. Voids in
the connector area may be eliminated by highly elongating the tape,
stretching it just short of its breaking point. Throughout the rest of
the splice less tension should be used. Always attempt to exactly
half‑lap to produce a uniform buildup. Continue buildup to 1‑1/2 times
cable diameter over the body of the splice with ends tapered a distance
of approximately 1 inch (25 mm) over the original jacket. Cover rubber
tape with two layers of vinyl pressure‑sensitive tape one‑half lapped.
Do not use glyptol or lacquer over vinyl tape as they react as solvents
to the tape. No further cable covering or splice boxes are required.

Heat shrinkable tubing shall be installed following manufacturer's
instructions. Direct flame heating shall not be permitted unless
recommended by the manufacturer. Cable surfaces within the limits of the
heat-shrink application shall be clean and free of contaminates prior to
application.

**108‑3.6 BARE COUNTERPOISE WIRE INSTALLATION FOR LIGHTNING PROTECTION
AND GROUNDING.** If shown on the plans or included in the job
specifications, bare counterpoise copper wire shall be installed for
lightning protection of the underground cables. Counterpoise wire shall
be installed in the same trench for the entire length of buried cable,
conduits and duct banks that are installed to contain airfield cables.
Where the cable or duct/conduit trench runs parallel to the edge of
pavement, the counterpoise shall be installed in a separate trench
located half the distance between the pavement edge and the cable or
duct/conduit trench. In trenches not parallel to pavement edges,
counterpoise wire shall be installed continuously a minimum of 4 inches
above the cable, conduit or duct bank, or as shown on the plans if
greater. Additionally, counterpoise wire shall be installed at least 8
inches below the top of subgrade in paved areas or 10 inches below
finished grade in un-paved areas. This dimension may be less than 4
inches where conduit is to be embedded in existing pavement.
Counterpoise wire shall not be installed in conduit.

The counterpoise wire shall be routed around to each light fixture base,
mounting stake, or junction/access structures. The counterpoise wire
shall also be exothermically welded to ground rods installed as shown on
the plans but not more than 500feet (150 m) apart around the entire
circuit.

The counterpoise system shall be continuous and terminate at the
transformer vault or at the power source. It shall be securely attached
to the vault or equipment external ground ring or other made electrode
grounding system. The connections shall be made as shown on the plans
and in the specifications.

If shown on the plans or in the specifications, a separate equipment
(safety) ground system shall be provided in addition to the counterpoise
wire using one of the following methods:

**(1)** A ground rod installed at and securely attached to each light
fixture base, mounting stake if painted, and to all metal surfaces at
junction/access structures.

**(2)** Install an insulated equipment ground conductor internal to the
conduit system and securely attached it to each light fixture base and
to all metal surfaces at junction/access structures. This equipment
ground conductor shall also be exothermically welded to ground rods
installed not more than 500 feet (150 m) apart around the circuit.

**a. Counterpoise Installation Above Multiple Conduits and Duct Banks.**
Counterpoise wires shall be installed above multiple conduits/duct banks
for airfield lighting cables, with the intent being to provide a
complete cone of protection over the airfield lighting cables. When
multiple conduits and/or duct banks for airfield cable are installed in
the same trench, the number and location of counterpoise wires above the
conduits shall be adequate to provide a complete cone of protection
measured 22 ½ degrees each side of vertical.

Where duct banks pass under pavement to be constructed in the project,
the counterpoise shall be placed above the duct bank. Reference details
on the construction plans.

**b. Counterpoise Installation at Existing Duct Banks.** When airfield
lighting cables are indicated on the plans to be routed through existing
duct banks, the new counterpoise wiring shall be terminated at ground
rods at each end of the existing duct bank where the cables being
protected enter and exit the duct bank. The new counterpoise conductor
shall be bonded to the existing counterpoise system.

**108-3.7 EXOTHERMIC BONDING.** Bonding of counterpoise wire shall be by
the exothermic welding process. Only personnel experienced in and
regularly engaged in this type of work shall make these connections.

Contractor shall demonstrate to the satisfaction of the Engineer, the
welding kits, materials and procedures to be used for welded connections
prior to any installations in the field. The installations shall comply
with the manufacturer\'s recommendations and the following:

All slag shall be removed from welds.

For welds at light fixture base cans, all galvanized coated surface
areas and \"melt\" areas, both inside and outside of base cans, damaged
by exothermic bond process shall be restored by coating with a liquid
cold-galvanizing compound conforming to U.S. Navy galvanized repair
coating meeting Mil. Spec. MIL-P-21035. Surfaces to be coated shall be
prepared and compound applied in accordance with manufacturer\'s
recommendations.

> All buried copper and weld material at weld connections shall be
> thoroughly coated 6 mil of 3M "Scotchkote," or approved equivalent, or
> coated with coal tar bitumastic material to prevent surface exposure
> to corrosive soil or moisture.\"

**108-3.8 TESTING.** The Contractor shall furnish all necessary
equipment and appliances for testing the airport electrical systems and
underground cable circuits before and after installation. The Contractor
shall perform all tests in the presence of the Engineer. The Contractor
shall demonstrate the electrical characteristics to the satisfaction of
the Engineer. All costs for testing are incidental to the respective
item being tested. For phased projects, the tests must be completed by
phase and results meeting the specifications below must be maintained by
the Contractor throughout the entire project as well as during the
ensuing warranty period.

Earth resistance testing methods shall be submitted to the Engineer for
approval. Earth resistance testing results shall be recorded on an
approved form and testing shall be performed in the presence of the
Engineer. All such testing shall be at the sole expense of the
Contractor.

Should the counterpoise or ground grid conductors be damaged or
suspected of being damaged by construction activities the Contractor
shall test the conductors for continuity with a low resistance ohmmeter.
The conductors shall be isolated such that no parallel path exists and
tested for continuity. The Engineer shall approve of the test method
selected. All such testing shall be at the sole expense of the
Contractor.

After installation, the Contractor shall test and demonstrate to the
satisfaction of the Engineer the following:

**a.** That all affected lighting power and control circuits (existing
and new) are continuous and free from short circuits.

**b.** That all affected circuits (existing and new) are free from
unspecified grounds.

**c.** That the insulation resistance to ground of all new non-grounded
series circuits or cable segments is not less than 50 megohms.

**d.** That the insulation resistance to ground of all non-grounded
conductors of new multiple circuits or circuit segments is not less than
50 megohms.

**e.** That all affected circuits (existing and new) are properly
connected in accordance with applicable wiring diagrams.

**f.** That all affected circuits (existing and new) are operable. Tests
shall be conducted that include operating each control not less than 10
times and the continuous operation of each lighting and power circuit
for not less than 1/2 hour.

**g.** That the impedance to ground of each ground rod does not exceed
25 ohms prior to establishing connections to other ground electrodes.
The fall-of-potential ground impedance test shall be utilized, as
described by ANSI/IEEE Standard 81, to verify this requirement.

Two copies of tabulated results of all cable tests performed shall be
supplied by the Contractor to the Engineer. Where connecting new cable
to existing cable, ground resistance tests shall be performed on the new
cable prior to connection to the existing circuit.

There are no approved \"repair\" procedures for items that have failed
testing other than complete replacement.

METHOD OF MEASUREMENT

**108‑4.1** Trenching shall be measured by the linear feet (meters) of
trench, including the excavation, backfill, and restoration, completed,
measured as excavated, and accepted as satisfactory.

When specified, separate measurement shall be made for trenches of
various specified widths.

The cost of all excavation, backfill, dewatering and restoration
regardless of the type of material encountered shall be included in the
unit price bid for the work.

**108‑4.2** Cable or counterpoise wire installed in trench, duct bank or
conduit shall be measured by the number of linear feet (meters) of cable
or counterpoise wire installed in trenches, duct bank or conduit,
including ground rods and grounding connectors, and trench marking tape
ready for operation, and accepted as satisfactory. Separate measurement
shall be made for each cable or counterpoise wire installed in trench,
duct bank or conduit. The measurement for this item **\[shall\] \[shall
not\]** include additional quantities required for slack.

**\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \***

> **Engineer to decide if the quantity of cable provided in the bid
> tabulations includes an estimated quantity for slack. If so, this
> should be clearly identified on the plans and specifications. If not,
> add the following language at the end of paragraph 108-4.2:**
>
> **"Cable and counterpoise slack is considered incidental to this item
> and is included in the contractor's unit price. No separate
> measurement or payment will be made for cable or counterpoise
> slack."**

**\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \***

BASIS OF PAYMENT

**108‑5.1** Payment will be made at the contract unit price for
trenching, cable and bare counterpoise wire installed in trench
(direct-buried), or cable and equipment ground installed in duct bank or
conduit, in place by the Contractor and accepted by the Engineer. This
price shall be full compensation for furnishing all materials and for
all preparation and installation of these materials, and for all labor,
equipment, tools, and incidentals, including ground rods and ground
connectors and trench marking tape, necessary to complete this item.

Payment will be made under:

> Item L‑108‑5.1 Trenching for direct-buried cable ---per linear foot
> (meter)
>
> Item L‑108‑5.2 **\[No. 8 AWG\] \[No. 6 AWG\]** L-824C Cable, installed
> in trench, duct bank or conduit---per liner foot (meter)

**\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \***

> **Engineer to specify appropriate size of cable. If more than one size
> is required on the project, provide additional item nos.; one for each
> size and type.**

**\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
\* \* \* \* \* \* \* \* \* \* \* \* \* \***

> Item L-108-5.3 Bare Counterpoise Wire, installed in trench, duct bank
> or conduit, including ground rods and ground connectors---per linear
> foot (meter)
>
> Item L-108-5.4 Bare or insulated equipment ground, installed in duct
> bank or conduit including ground rods and ground conductors -- per
> linear foot (meter).

MATERIAL REQUIREMENTS

> AC 150/5345‑7 Specification for L‑824 Underground Electrical Cable for
> Airport Lighting Circuits
>
> AC 150/5345‑26 Specification for L‑823 Plug and Receptacle Cable
> Connectors
>
> FED SPEC J‑C‑30 Cable and Wire, Electrical Power, Fixed Installation
> (cancelled; replaced by A-A-59544 Cable and Wire, Electrical (Power,
> Fixed Installation))
>
> FED SPEC A-A-55809 Insulation Tape, Electrical, Pressure‑Sensitive
> Adhesive,
>
> Plastic
>
> ASTM B 3 Soft or Annealed Copper Wire
>
> ASTM D 4388 Rubber tapes, Nonmetallic Semiconducting and Electrically
> Insulating

REFERENCE DOCUMENTS

> NFPA No. 70 National Electrical Code (NEC)
>
> MIL-S-23586C Sealing Compound, Electrical, Silicone Rubber
>
> Building Industry Consulting Service International (BICSI)
>
> ANSI/IEEE Std 81 IEEE Guide for Measuring Earth Resistivity, Ground
> Impedance, and Earth Surface Potentials of a Ground System

**END OF ITEM L‑108**

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