-
FAA GREAT LAKES REGION
DEVELOPMENT OF STATE STANDARDS FOR NON-PRIMARY AIRPORTS
In accordance with 49 U.S. C. 47105 (c)
.. . . DESCRIPTION OF REQUEST I. TITLE OF STANDARD(S) BEING
MODIFIED (CITE REFERENCE DOCUMENT):
AC1SO/S370-l00 modifying Part 11: L-108, L-109, L-110, L-115 and
L-119
2. STANDARD/REQUIREMENT:
Construttion specifications for electrical work on airports
3. DESCRIPTION OF PROPOSED MODIFICATION:
Specifically set up the specifications for state ofMichigllD
airports
4. IS THE PROPOSED MODIFlCATJON DERIVED FROM STATE
HlOHWAYSPECIFICATIONS?
No
S. EXPLAIN WHY THE STANDARD(S) CANNOT BE MET:
We have modified the FAA conslruclion specifications to better
meet the needs of the consultants ond c0t1lrac1ors using these
conslruclion specificalions in lhe state ofMichig1111. We have
found over lhe ycm it is better to have consistent construction
specilicntlons for lhc state ofMichigan airport projects rather
than have each oonsul_tant sci up different variations oflhe
constroction specifications.
6. ASSURANCE THAT THE PROPOSED MODIFICATION WILL PROVTDE
APRODUCT THAT WILL MEET FAA STANDARDS FOR ACCEPTANCE AND TiiAT TiiE
FINISHED PRODUCT WILL PERFORM FOR ITS IN1ENDED DESIGN LIFE, BASED
ON HISTORICAL DATA OR MODlFICATlON IS NECESSARY TO CONFORM TO LOCAL
LAWS AND REGULATIONS (IF APPLICABLE).
7. REQUEST JS APPLICABLE TO NON.PRIMARY AIRPORTS AT WHAT
STATE?
Michigan
ATTACH MODIFIED VERSION OF AC 150/537010 WITH TRACK CHANGES
AGL DEVELOPMENT OF STATE STANDARDS Page I of3
REQUEST FORM Revised S/2/2017
-
FAA GREAT LAKES REGION
DEVELOPMENT OF STATE STANDARDS FOR NON-PRIMARY AIRPORTS
8. .. CHECK WHEN APPLICABLE
Modifications to materials standards is requested because
locally available materials cannot meet the requirements ofthatD
standard.
Modifications to construction methods standards will result in
cost savings and/or greater efficiency. 5:( Bids have already been
received for this project.D
IF ANY OF THE ABOVE IS CHECKED PLEASE PROVIDE ADDITIONAL
DETAILS.
9.SION~Tive, 10. PRJNTEDNAME OF STATE REPRESENTATlVB II.DATE
Carol Aldrich 01/04/2016
12. STATE REPRESENTATIVE'S TITLE 13. TELEPHONE 14. E-MAIL
MOOT Office ofAeronautics Sl733S-9804 [email protected]
AGL DEVELOPMENTOFSTATESTANDARDS Puge2of3 . REQUEST FORM Revised
S/2J20l7
-
BELOW IS TO BE COMPLETED BY FAA JS. ADO RECOMMENDATION: 16.
SIGNATURE: 17.DATE:
ROlTilNO SYMBOL SIGNATURE DATE CONCUR NON-CONCUR
AGL-622 05/02/2017 X~
COMMENTS:
18. AIRPORTS' DIVISION FINAL ACTION:
D
TITLE:
N
AOL DEVELOPMENT OF STATE STANDARDS Page3of3
REQUEST FORM Revised S/2/2017
-
Michigan Department of Transportation Office of Aeronautics
Item L-108 Underground Power Cable for Airports
For NonPrimary Airports
DESCRIPTION
108-1.1 This item shall consist of furnishing and installing
power cables that are direct buried and furnishing and/or
installing power cables within conduit or duct banks per 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 manufacturers
certification of compliance with the applicable specification, when
requested by the Engineer.
c. Manufacturers certifications shall not relieve the Contractor
of the responsibility to provide materials per these specifications
and acceptable to the Engineer. Materials supplied and/or installed
that do not comply with these specifications shall be removed when
directed by the Engineer and replaced with materials that comply
with these specifications at the Contractors cost.
d. Documentation for all materials and equipment used to
construct this item shall be submitted to the Engineer for
acceptance prior to ordering the equipment. Five (5) sets of
Submittals consisting of marked catalog sheets or shop drawings
shall be provided. Submittal that have been accepted shall be
distributed as follows: One to Engineer, One to Owner, One to
MDOT-AERO, Two to Contractor. If Contractor requires more than two
returned sets, then Contractor shall submit number of additional
sets required. 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 any non-pertinent data.
Submittals for components of electrical equipment and systems shall
identify the equipment to which they apply on each submittal sheet.
Markings shall be made bold and clear with arrows or circles
(highlighting is not acceptable). The Contractor is solely
responsible for delays in the project that may accrue directly or
indirectly from late submissions or resubmissions of
submittals.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
1
-
With approval of the Engineer, the Contractor can submit
material/equipment documentation electronically for review,
comment, and/or acceptance by the Engineer. At the Engineers
option, accepted submittals can be scanned as pdf files and
electronically transmitted to the Contractor.
e. The data submitted shall be sufficient, in the opinion of the
Engineer, to determine compliance with the plans and
specifications. The Engineer reserves the right to reject any and
all equipment, materials, or procedures which, in the Engineers
opinion, does not meet the system design and the standards and
codes, specified in this document.
f. All equipment and materials furnished and installed under
this section shall be guaranteed against defects in materials and
workmanship for a period of twelve (12) months from the date of
final acceptance by the Owner. The defective materials and/or
equipment shall be repaired or replaced, at the Owners discretion,
with no additional cost to the Owner. All new underground wiring
shall maintain a minimum Insulation Resistance to ground (IR) in
accordance with L-108.3.9.c during the guarantee period. If, based
on IR testing, wire IR is determined to be less than specified, the
Contractor shall determine the cause of the unacceptable IR and
correct that cause. Specified in para. 108-2.1.d.
108-2.2 Cable. Underground cable for airfield lighting
facilities (runway and taxiway lights, guidance signs, REIL, PAPI,
wind cones and beacons) shall conform to the requirements of AC
150/5345-7, Specification for L-824 Underground Electrical Cable
for Airport Lighting Circuits latest edition. Conductors for use on
6.6 ampere primary airfield lighting series circuits shall be
single conductor, seven strand, #8 American wire gauge AWG), L-824,
5,000 volts, nonshielded, type and insulation as specified in the
plans and contract documents and in accordance with these L-108
specifications. Conductors for use on 20 ampere primary airfield
lighting series circuits shall be single conductor, seven strand,
#6 AWG, L-824 5,000 volts, nonshielded, type and insulation as
specified in the plans and contract documents and in accordance
with these L-108 specifications. L-824 conductors for use on the
L-830 secondary of airfield lighting series circuits shall be sized
in accordance with the manufacturers recommendations. All other
conductors shall comply with FAA and National Electric Code (NEC)
requirements. Conductor sizes noted in this AC shall not apply to
leads furnished by manufacturers on airfield lighting transformers
and fixtures.
Wire for electrical circuits up to 600 volts and less shall
comply with Specification L-824 and/or Federal Specification
A-A-59544 and shall be type THWN-2, 75C. Conductors for parallel
(voltage) circuits shall be sized and installed in accordance with
NFPA-70, National Electrical Code.
Unless noted otherwise, all 600-volt and less non-airfield
lighting conductor sizes are based on a 75C, THWN-2, 600 volt
insulation, copper conductors, not more than three single insulated
conductors, in raceway, in free air. The conduit/duct sizes are
based on the use of THWN-2, 600 volt insulated conductors. The
Contractor shall make the necessary increase in conduit/duct sizes
for other types of wire insulation. In no case shall the
conduit/duct size be reduced. The minimum power circuit wire size
shall be #12 AWG.
Conductor sizes may have been adjusted due to voltage drop or
other engineering considerations. Equipment provided by the
Contractor shall be capable of accepting the quantity and sizes of
conductors shown in the Contract Documents. All conductors,
pigtails, cable step-down adapters, cable step-up adapters,
terminal blocks and splicing materials necessary to complete the
cable termination/splice shall be considered incidental to the
respective pay items provided.
Cable type, size, number of conductors, strand and service
voltage shall be as specified in the Contract Documents.
108-2.3 Bare copper wire (counterpoise, bare copper wire ground
and ground rods). Wire for counterpoise or ground installations for
airfield lighting systems shall be No. 6 AWG bare solid copper Item
L-108 Underground Power Cable for Airports Approved by FAA / /
2
-
wire for counterpoise and/or No. 6 AWG insulated stranded for
ground wire conforming to ASTM B3 and ASTM B8, and shall be bare
copper wire where soils are noncorrosive to copper or tinned copper
where soils are corrosive to copper conforming to the requirements
of ASTM B33. Whether bare or tinned shall be as specified in the
contract documents. See AC 150/5340-30 for additional details about
counterpoise and ground wire types and installation. For voltage
powered circuits, the equipment ground conductor shall be minimum
No. 6 AWG, 600V rated, Type XHHW insulated, green color, stranded
copper equipment ground conductor.
Ground rods shall be 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 in diameter. Ground
rods shall be UL 467 listed and comply with NEMA GR-1.
Connections of counterpoise wire and ground wire to ground rods
shall be exothermic and shall be UL 467 and UL 96 listed.
Requirement for bare or tinned to be included in the contract
documents.
108-2.4 Cable connections. In-line connections or splices 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 3MTM Company,
Scotchcast Kit No. 82-F1 (size B), or as manufactured by Hysol
Corporation, Hyseal Epoxy Splice Kit No. E1135, or an approved
equivalent, used for potting the splice is acceptable.
b. The field-attached plug-in splice. Field-attached plug-n
splices meeting the requirements of AC 150/5345-26 (latest
edition), Specification for L-823 Plug and Receptacle, Cable
Connectors, employing connector kits, are acceptable for field
attachment to single conductor cable. It shall be the Contractors
responsibility to determine the outside diameter of the cable to be
spliced and to furnish appropriately sized connector kits and/or
adapters. If specified in the plans, field-attached splices shall
be covered with heat shrink tubing with integral sealant. The
center splice joint shall not be covered with hear shrink.
Splice kits shall be of a style having an integral overlap boot
at the splice joint, such as manufactured by Integro (Complete
Kit), Amerace (Super 54D4D4), or accepted equivalent.
c. The factory-molded plug-in splice. Specification for L-823
Connectors, Factory-Molded to Individual Conductors, is
acceptable.
d. The taped or heat-shrink splice. Taped splices employing
field-applied rubber, or synthetic rubber tape covered with plastic
tape is acceptable. The rubber tape shall meet the requirements of
ASTM D4388 and the plastic tape should comply with Military
Specification MIL-I-24391 or Fed. Spec. A-A55809. 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 that are
designed for the application. Heat shrinkable tubing and tubing
kits shall be manufactured by Tyco Electronics/ Raychem
Corporation, Energy Division, or accepted equivalent.
Heat-shrink tubing shall be heated using a heat gun intended for
the purpose. NO OPEN FLAME TORCHES shall be permitted.
In all the above cases, connections of cable conductors shall be
made using crimp connectors using 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 per the manufacturers
recommendations and listings.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
3
-
e. Counterpoise and Ground Connections. All connections of
counterpoise, and grounding conductors to ground rods shall be made
by the exothermic process, irreversible crimp, or accepted
equivalent. All exothermic connections shall be made per the
manufacturers recommendations and listings. Connection of light
base ground conductors to light base ground strap (internal or
external as specified in the plans) shall be a mechanical grounding
connection. Bolts with brass washers are specifically prohibited
for use as ground clamps.
Because the counterpoise and ground systems serve different
purposes, counterpoise wire and ground wire shall not be connected
to the same ground rod.
108-2.5 Splicer qualifications. Every airfield lighting cable
splicer shall be qualified in making cable splices and terminations
on cables rated at or above 5,000 volts AC. The Contractor shall
submit to the Engineer proof (such as splicers work experience) 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.
All crimped splices shall be made with crimping tools that
require completion of a crimp before the tool will release.
108-2.6 Concrete. Concrete for cable markers shall be per
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 FAA specification Item P-153, Controlled Low Strength Material
or as specified in the plans.
108-2.8 Cable identification tags. If called for in the plans,
circuits shall be identified at each access point (such as electric
manholes and handholes) using the circuit identifications specified
in the plans.
Cable identification tags shall be made from a non-corrosive
material with the circuit identification stamped or etched onto the
tag. The tags shall be of the type and labeling as detailed on the
plans.
108-2.9 Tape. Electrical tapes shall be 8.5 mil vinyl electrical
tape and 30 mil linerless rubber splicing tape, such as Scotch 88
vinyl (1-1/2 inch wide) and ScotchTM 130C linerless rubber splicing
tape (2-inch wide), as manufactured by the Minnesota Mining and
Manufacturing Company (3MTM), or an approved equivalent.
108-2.10 Electrical coating. Electrical coating shall be
Scotchkote as manufactured by 3MTM, or an approved equivalent.
108-2.11 Existing circuits. The Contractor shall provide
underground cable locating equipment and operator. Locating
equipment can be either conductive (attaches to a de-energized
wire) or inductive (clamps around an energized or de-energized
wire), at the contractors discretion. Working in consultation with
the Engineer, Contractor shall locate existing underground wiring
in the proposed work area. Cost of providing toning equipment and
locating existing underground wiring shall be included in Pay Item
1000400, Mobilization and General Conditions.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
4
http:108-2.11http:108-2.10
-
Whenever the scope of work requires connection to an existing
circuit, the existing circuits insulation resistance (IR) to ground
shall be tested, in the presence of the Engineer. The test shall be
performed in accordance with this item and prior to any activity
that will affect the respective circuit. The Contractor shall
record the results on forms acceptable to the Engineer. This before
test shall be the basis of acceptance of the overall circuit IR to
ground after connection of new wiring to existing wiring.
After the new wiring has been installed, but not yet connected
to the existing circuit, the new wiring insulation resistance to
ground shall be tested with a minimum resistance to ground meeting
the requirements of L-108-3.9.c.
After the new wiring is connected to the existing circuit and
work affecting the existing circuit is complete, the overall
circuits IR shall be checked again, in the presence of the
Engineer. The Contractor shall record the results on forms
acceptable to the Engineer. The after connection reading shall be
equal to or greater than the existing circuits initial reading. If
not, the Contractor shall make the necessary repairs to the circuit
to make the second reading equal to or greater than 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.
108-2.12 Detectable warning tape. Plastic, detectable, American
Wood Preservers Association (AWPA) Red (electrical power lines,
cables, conduit and lighting cable) with continuous legend magnetic
tape shall be polyethylene film with a metalized foil core and
shall be 3-6 inches (75-150 mm) wide. Detectable tape is incidental
to the respective bid item.
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.
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.
Cable connections between lights will be permitted only at the
light locations for connecting the underground cable to the primary
leads of the individual lamp (i.l.) isolation transformers. No
cable connections are permitted between lights.
In addition to connectors being installed at i.l. transformers,
additional 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
maintenance/test point L-823 connectors installed or at least
single identification marker in each access point where L-823
connectors are not installed. Maintenance/test point L-823
connectors shall be installed in electric handholes or manholes, if
specified in the plans.
Provide not less than 3 feet of cable slack on each side of all
connections, i.l. transformers, light units, and at points where
cable is connected to field equipment. This requirement also
applies where 5kV cable passes through empty base cans, junction
boxes, and access structures to allow for future connections in the
structures, or as designated by the Engineer. Cost of slack cable
in these instances shall be considered incidental to the pay item
cable quantity.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
5
http:108-2.12
-
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 3 feet vertically above the top of the access
structure. Cost of this slack cable shall be included in the
appropriate pay item cable quantity.
In manholes and electrical structures, each cable shall be
routed around the interior wall and looped prior to exiting. These
cables shall be racked in place.
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, hand holes, pull boxes,
junction boxes, etc. Markers shall be of sufficient length for
imprinting the cable circuit identification legend on one line,
using letters not less than 1/4 inch (6 mm) in size. The cable
circuit identification shall match the circuits noted on the
construction plans.
At each i.l. transformer, in addition to the circuit
identification marker, the contractor shall wrap color coding tape
on both sides of each connection (minimum of 2 inches of taping
each side of connection) so as to be able to identify the circuits
physical direction of routing. Color coding shall be red for
incoming circuit and blue got outgoing circuit. Incoming and
outgoing shall be established at the beginning of a circuit and
shall be consistent at each light throughout the circuit. Tape
shall be 3M Scotch 35 Vinyl Electrical Tape, or accepted equal.
108-3.2 Installation in duct banks or conduits. This item
includes the installation of the cable in duct banks or conduit per
the following paragraphs. 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 per the latest
version of the National Electric Code, or the code of the local
agency or authority having jurisdiction.
In no event shall airport low voltage (600v) wire and airport
high voltage (5,000v) wire be installed in the same conduit or
duct.
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 that any potential interference is avoided.
Duct banks or conduits shall be installed as a separate item per
Item L-110, Airport Underground Electrical Duct Banks and Conduit.
Prior to installing new wire, the Contractor shall mandrel
individual conduit whether the conduit is direct-buried or part of
a duct bank to ensure that the conduit is open, continuous and
clear of debris. The mandrel size shall be compatible with the
conduit size. Mandrels shall be rubber, polyurethane, or leather or
accepted equivalent. The Contractor shall swab out all
conduits/ducts and clean base cans, manholes, 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 or the item being installed. All raceway
systems left open, after initial cleaning, for any reason shall be
re-cleaned at the Contractors 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, damage 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. The pulling of a cable through duct
banks or conduits may be accomplished by hand winch or power winch
with the use of cable grips or pulling eyes. Maximum pulling
tensions shall be governed by Item L-108 Underground Power Cable
for Airports Approved by FAA / /
6
-
cable manufacturers recommendations. A non-hardening lubricant
(such as American Polywater J or NN, or sccepted equivalent)
recommended for the type of cable being installed shall be used
where pulling lubricant is required. 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 Contractor shall submit the 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
Contractors expense.
The manufacturers minimum bend radius or NEC requirements
(whichever is more restrictive) shall apply. Cable installation,
handling and storage shall be per manufacturers recommendations.
During cold weather, particular attention shall be paid to the
manufacturers minimum installation temperature. Cable shall not be
installed when the temperature is at or below the manufacturers
minimum installation temperature. At the Contractors 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
manufacturers minimum cable installation temperature.
Cable to be pulled or being pulled shall not be dragged across
light base, manhole, or conduit/duct edges, pavement or earth.
Cable shall be unreeled and hand guided or run through a feeder
tube when entering horizontal duct systems. When cable must be
coiled, lay cable out on a canvas tarp or use other appropriate
means to prevent abrasion to the cable jacket.
In manholes and pull boxes, each cable shall be routed around
the structure interior wall and shall be racked in place, or
securely fastened in a manner accepted by the Engineer. Cost of
racking/securing cable in a structure shall be incidental to the
pay item cable quantity.
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 (see Specification L-108-3.4). Cable shall be
unreeled uniformly in place alongside or in the trench and shall be
carefully placed along the bottom of the trench. The cable 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 inches
vertical displacement shall be provided with the topmost cable
depth at or below the minimum required depth below finished
grade.
Airport low voltage (600v) wire and airport high voltage
(5,000v) wire shall be installed with a minimum of 12 inches
separation.
NOTE: where 600v circuit are run on 5,000v wire, these circuits
can be installed in the same trench with 5,000v circuits with the
standard 3 inch spacing within the trench.
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, pull boxes,
junction boxes, etc. Markers shall be of sufficient length for
imprinting the cable circuit identification shall match the
circuits noted on the construction plans.
a. Existing Cables. It is the Contractors responsibility to
locate existing utilities within the work area prior to excavation
(see L-108-2.11). Where existing active cables across proposed
installations, the Contractor shall ensure that these cables are
adequately protected. Where crossings are unavoidable, no splices
will be allowed in the existing, except as specified on the plans.
Installation of new cable where such crossings must occur shall
proceed as follows:
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
7
http:L-108-2.11
-
i. Existing cables shall be located manually through the use of
60 Hz toning equipment and hand digging. To help avoid damage,
mechanical diggers shall not be used to depths greater than 12
inches when exposing existing cables. Unearthed cables shall be
inspected to assure absolutely no damage has occurred.
ii. Trenching, cable installation, and backfill 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. Installation of new
cable shall maintain a minimum 18 inches below grade.
If existing cables are encountered at 18 inches depth, new
cables shall be installed at least 3 inches beneath existing cables
through careful hand digging beneath existing cables, installing
the new cable(s) below the existing cables, and installing a 3 inch
Styrofoam block between existing and new cables to maintain
separation.
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, as determined
by the Engineer.
b. 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
per NEC Table 300.5, except as follows:
i. When off the airport or crossing under a roadway or driveway,
the minimum depth shall be 36 inches unless otherwise
specified.
ii. 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. Where more than
two cables are to be installed in a trench, the trench width shall
be increased 3 inched for each additional cable.
When rock, stone, or other unsuitable trench conditions are
encountered, and it is specified in the plans, 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
and bedding replacement 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 Contractors responsibility to locate existing
utilities within the work area prior to excavation. Where existing
active cables cross proposed installations, the Contractor shall
ensure that these cables 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:
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
8
-
i. Existing cables shall be located manually. Unearthed cables
shall be inspected to assure absolutely no damage has occurred.
ii. 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.
c. Warning Tape. If specified on the plans or in the contract
documents underground electrical warning (caution) tape shall be
installed in the trench above all direct-buried cable and conduit
installations. Contractor shall submit a sample of the proposed
warning tape for acceptance by the Engineer. The warning tape shall
be located 6 inches above the direct-buried cable (at the top of
the second level of fill) or the counterpoise wire if present. A
3-6 inch wide polyethylene film tape with a metalized foil core
(magnetic tracer), AWPA Red 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
of the color and have a continuous legend as indicated on the
plans. The tape shall be installed 8 inches minimum below finished
grade. Detectable warning tape is incidental to the respective pay
item.
d. 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 3rd 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 per the plans and specifications.
e. Restoration. Following restoration of all trenching near
airport movement surfaces, the Contractor shall visually inspect
the area for foreign object debris (FOD) and remove any that is
found. 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 restoration method(s) and materials
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 pavement section 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.
108-3.4 Installation of Direct-Buried Cable Via Cableplowing.
Cable plowing, when specified in the plans and/or specifications,
shall be accomplished using equipment and construction methods
meeting the following specifications. Unless directed otherwise by
the Engineer, cable plowing shall not be used in the gravelly,
rocky, or stony soils.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
9
-
a. Equipment. The cable plowing equipment shall be of the
vibratory type having a vibrating rate of at least 1,200 cycles per
minute. The vibrating unit shall be attached to a tractor unit in
such a manner that the tractor does not dampen the vibration.
The plow table shall be of sufficient length of to permit
installation of the cable at the specified depth. The shoe throat
shall be configured and sized for cables specified, having one
chute per cable being installed. Chutes shall be spaced to maintain
required cable separation.
The plow cableway and guides shall be smooth, free of
obstructions and sharp edges and shall not cause bending of the
cable tighter than a 3 inch radius (#8 and #6 AWG wire), nor cause
excessive cable strain.
b. Personnel. Plow operators shall be experienced and qualified
by schooling and/or experience. The Contractor shall provide such
proof of qualification if requested by the Engineer.
c. Installation. Cable routing shall be offset 2 feet from the
light line (either side away from or side toward runway/taxiway
pavement), or in line with light line. Cable routing shall be as
specified in the plans. A hole, typically 2 feet in diameter, shall
be dug at each light location to enable looping cable (8 feet loop
minimum) at each location.
Cable reels can be mounted on the tractor or cable unreeled
along the proposed cable route before plowing. The cable-plow
pulling cable from a separate, nonplow mounted reel will not be
permitted.
After the cable plow in positioned at the beginning of a run,
sufficient cable slack shall be pulled through the throat to enable
lowering the plow into the starter hole without tensioning the
cable. The cable shall be handheld and guided for the beginning of
the plow run.
At each light hole, plow movement and vibration shall be
stopped, the plow raised and the required amount of slack cable
hand pulled. Care shall be taken during this operation so that the
cable at the light hole shall not be pulled from the specified
depth. Cable shall not be cut until ready to be installed into
light base. Plowing shall be continued by lowering the plow,
starting it and holding the cable by hand until the plow and cable
are firmly in place.
The plow shall not be backed onto the cable.
If an underground obstruction in encountered, the plow shall be
lifted out of the ground and the obstruction removed by hand
digging. The plow shall be forced beyond an obstruction. During the
plow lifting, obstruction removal, and plow reinsertion, care shall
be taken that the cable has no bends sharper than 3 inch radius and
is not subject to excessive tension.
After a cable plowing operation, the disturbed earth shall be
leveled by a method approved by the Engineer and, if necessary,
compacted by a device approved by the Engineer.
Ends of all cut cable shall be taped and sealed immediately to
prevent the entrance of moisture.
If specified in the plans, installation of detectable warning
(caution) tape shall be required when wire is installed by cable
plowing.
108-3.5 Cable markers for direct-buried cable. The location of
direct buried circuits shall be marked by a concrete slab marker, 2
feet square and 4-6 inch thick. Markers shall be installed so as to
protrude approximately 1 inch above the surface. Each cable run
(homerun) from a line of lights and signs to the equipment vault
shall be marked at approximately every 200 feet 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 high and 3 inches wide, with width of stroke 1/2 inch and
1/4 inch deep.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
10
-
At the location of each underground cable connection, except at
lighting units, i.l. 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.
108-3.6 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 per the manufacturers instructions and to
the satisfaction of the Engineer.
b. Field-attached plug-in splices. These shall be assembled per
the manufacturers instructions. These splices shall be made by
plugging directly into mating connectors. In all cases the joint
where the male and female connections join 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 on
each side of the joint or shall be heat shrink covered. However,
L-823 splice kits (such as Amerace 54 Super Kit or Integro Complete
Kit) containing a connection joint overlap do not require taping or
heat shrink unless specified on the plans.
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 11/2 inches on
each side of the joint.
d. Taped or heat-shrink 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 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 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 (see L-108-2.9) 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 1inch over the original jacket. Cover rubber tape
with two layers of vinyl pressure-sensitive tape one-half lapped
(see L-108-2.9). Cover vinyl tape with an electrical coating (see
L-1082.10). 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
manufacturers instructions. Direct flame heating shall not be
permitted unless recommended by the manufacturer and approved by
the Engineer. Cable surfaces within the limits of the heat-shrink
application shall be clean and free of contaminates prior to
application and shall be dried. There should be no moisture
remaining on the cable insulation within the hear shrink to
eliminate heat shrink gaping and the later entrance of moisture.
Item L-108 Underground Power Cable for Airports Approved by FAA /
/
11
-
108-3.7 Bare counterpoise wire installation for lightning
protection and grounding. If shown on the plans or included in the
job specifications, No. 6 AWG bare solid copper counterpoise wire
shall be installed for lightning protection of the underground
cables.
a. Counterpoise Systems. The Engineer shall select one of two
methods of lightning protection for the airfield lighting circuit
based on the frequency of local lightning:
i. Equipotential. may be used by the Engineer for areas that
have high rates of lightning strikes. This is where the
counterpoise is bonded to the light base (edge lights included) and
counterpoise size is determined by the Engineer, if other than
#6.
ii. Isolation used in areas where lightning strikes are not
common. The counterpoise is not bonded to edge light fixtures,
however in-pavement fixtures are boned to the counterpoise.
Counterpoise size is selected by the Engineer.
b. Counterpoise Installation. - 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, except where the cable or duct/conduit trench runs parallel
to the edge of pavement. In this instance the counterpoise shall be
installed in a separate trench located half the distance between
the pavement edge and the cable or duct/conduit trench at a depth
of 8 inches. 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 p-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.
c. Counterpoise for Raceways and Cable. - For raceways installed
under pavement; for raceways and cables not installed adjacent to
the full strength pavement edge; for fixtures installed in full
strength pavement and shoulder pavement and for optional method of
edge lights installed in turf (stabilized soils); and for raceways
or cables adjacent to the full strength pavement edge, the
counterpoise conductor shall be centered over the raceway or cable
to be protected as described below.
The counterpoise conductor shall be installed no less than 8
inches above the raceway or cable to be protected, except as
permitted below.
The minimum counterpoise conductor height above the raceway or
cable to be protected shall be permitted to be adjusted subject to
coordination with the airfield lighting and pavement designs.
Where raceway is installed by the directional bore, jack and
bore, or other drilling method, the counterpoise conductor shall be
permitted to be installed concurrently with the directional bore,
jack and bore, or other drilling method raceway, external to the
raceway or sleeve.
The counterpoise conductor shall be installed no more than 12
inches (305 mm) above the raceway or cable to be protected.
The counterpoise conductor height above the protected raceway(s)
or cable(s) shall be calculated to ensure that the raceway or cable
is within a 45-degree area of protection.
d. Grounding Runway and Taxiway Light Fixtures. - Each light
base or mounting stake shall be provided with a grounding
electrode.
When a metallic light base is used, the grounding electrode
shall be bonded to the metallic light base or mounting stake with a
No. 6 AWG bare, annealed or soft drawn, solid copper conductor.
When a nonmetallic light base is used, the grounding electrode
shall be bonded to the metallic light fixture or metallic base
plate with a No. 6 AWG bare, annealed or soft drawn, solid copper
conductor.
The counterpoise conductor shall be bonded to each metallic
light base, mounting stake, and metallic airfield lighting
component only if specified in the contract documents. Item L-108
Underground Power Cable for Airports Approved by FAA / /
12
-
All metallic airfield lighting components in the field circuit
on the output side of the constant current regulator (CCR) or other
power source shall be bonded to the airfield lighting counterpoise
system if specified in the contract documents.
Unless otherwise specified in the contract documents, the
counterpoise wire shall not be connected to light bases, mounting
stakes, junction boxes, electric manholes and handholes. The
counterpoise wire shall also be exothermically welded to ground
rods installed as shown on the plans but not more than 500 feet
(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 by exothermic weld or other
accepted equivalent as shown on the plans and in the
specifications. Counterpoise connections shall be UL 467 and UL 96
listed.
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:
i. A 5/8 x 8 foot ground rod, or other size as specified in the
plans, installed at and securely attached to each light fixture
base, mounting stake if painted, and to all metal surfaces at
junction/access structures using #6 AWG copper wire. Ground wire
shall be mechanically attached to a ground strap at the light
fixture or in the electrical structure; or,
ii. Install a green 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 (150m) apart around the circuit separate from the counterpoise
ground rods.
iii. For parallel voltage systems only, install a #6 AWG green
insulated equipment ground conductor internal to the conduit system
and securely attach it to each light fixture base/stake internal
grounding lug and to all metal surfaces at junction/access
structures. Dedicated ground rods shall be installed and
exothermically welded to the counterpoise wires at each end of a
duct bank crossing under pavement.
Where an existing airfield lighting system is being extended or
modified, the new counterpoise conductors shall be interconnected
to existing counterpoise conductors at each intersection of the new
and existing airfield lighting counterpoise systems.
e. 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 22-1/2 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.
f. 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.
108-3.8 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.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
13
-
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 manufacturers recommendations
and the following:
a. All slag shall be removed from welds.
b. 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 Military
Specification for high zinc dust content galvanizing repair coating
meeting specification DOD-P-21035 for zinc galvanizing spray paint.
Surfaces to be coated shall be prepared and regalvanizing material
applied in accordance with manufacturers recommendations.
Unless otherwise shown on the plans, new light fixture base cans
shall include a ground strap (internal or external to accommodate
the fixture ground wire) capable of accepting a mechanical ground
wire fastening lug. Using an exothermic weld to bond the
counterpoise to a lug on a galvanized light base is not recommended
unless the base has been specially modified. Consult the
manufacturers installation directions for proper methods of bonding
copper wire to the light base. See also AC 150/5340-30 for
galvanized light base exception.
c. All buried copper and weld material at weld connections shall
be thoroughly coated with 6 mil of 3MTM ScotchkoteTM, or approved
equivalent, or coated with coal tar Bitumastic material to prevent
surface exposure to corrosive soil or moisture.
108-3.9 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. The Contractor must
maintain the test results throughout the entire project as well as
during the 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 and shall be included in the bid prices
for the items being tests.
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, to the extent circuits have been impacted by new
construction, and new) are continuous and free from short circuits.
This test shall be combination of visual and operational tests in
the presence of the Engineer.
b. That all affected circuits (existing and new) are free from
unspecified grounds. This shall be a visual and operational test in
the presence of the Engineer. For series circuits, passing the
insulation resistance (IR) test c. below will be proof of no
unspecified grounds.
c. That completed series circuits (with Isolation Transformers
connected) and parallel circuit homeruns are meggered to insure an
insulation resistance to ground (IR) of at least 500 megohms, or
as
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
14
-
specified in the plans. Caution: In a parallel (multiple) system
all lamps, transformers, contactors, and any grounded item must be
removed from the homerun circuit prior to meggering.
Circuits using 600v wire shall be meggered with a 500v
megohmeter. Circuits using 5,000v wire shall be meggered with a
1,000v megohmeter.
d. That continuity of each series circuit is checked with an
ohmmeter. Expected resistance should be approximately 20 ohms (plus
or minus depending on circuit length). A resistance above 100 ohms
may indicate a potential system problem, such as loose (partial
open) or poorly made L-823 connector or possible cable break inside
the insulation.
A reading greater than 100 ohms, at the discretion of the
Engineer, shall be cause to troubleshoot the system to ascertain
and repair the cause of a high resistance reading.
e. That all affected circuits (existing and new) are properly
connected per applicable wiring diagrams. This test shall be a
combination of visual inspection and operational tests in the
presence of the Engineer. Operational tests shall include operating
(on/off) each circuit a minimum of five (5) times with a minimum
operating ON time of hour after the fifth on/off operation. The
tests are in addition to test (f) below. The Engineer may specify
additional test parameters in the plans.
f. That all affected circuits (existing and new) operate
correctly. 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
used, as described by ANSI/IEE Standard 81, to verify this
requirement. As an alternate, clamp-on style ground impedance test
meters may be used to satisfy the impedance testing requirement.
Test equipment and its calibration sheets shall be submitted for
review and approval by the Engineer prior to performing the
testing.
h. That electrical impedance to ground of a new vault ground
system shall not exceed 10 ohms.
i. That all cable connections have been properly made. The
contractor shall include in his bid the exposing (either by opening
of light bases or digging up of buried connections) of up to five
(5) cable connections for inspection. Connections to be exposed
shall be randomly chosen by the Engineer. If any of the five
selected connections fail inspections, that connection shall be
repaired/replaced, at the Engineers option. Also, the Engineer may
exercise an option to expose and inspect as many additional
connections at no additional cost to the project. Replacement of
all failed connectors shall be a no cost to the Project.
j. Expose a section of cable of sufficient length in each
homerun to verify the cable meets the specifications listed in the
plans and proposal, unless prior verified during construction
inspection.
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, unless directed
otherwise by the Engineer.
METHOD OF MEASUREMENT
108-4.1 Trenching shall be measured by the linear feet of
trench, including the excavation, backfill, and restoration,
completed, measured and accepted as satisfactory. When specified,
separate measurement shall be made for trenches of various
specified widths.
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
15
-
The cost of all excavation, backfill with excavated material,
dewatering and restoration regardless of the type of material
encountered shall be included in the unit price bid for the
work.
If specified in the plans, use of backfill sand for rocky or
stony trenches shall be measured on a per cubic yard basis with
that measurement based on 6 inches of sand backfill (3 inches as
sand bedding in bottom of trench below wires; 3 inches as backfill
above wires) times the trench width times the trench length. This
shall be a calculated cubic yard quantity with no adjustments made
for shrinkage and loss.
108-4.2 Cable or counterpoise wire installed in trench, duct
bank or conduit shall be measured by the number of linear feet of
cable or counterpoise were installed in trenches, duct back or
conduit, including ground rods and grounding connectors, and trench
marking tape ready for operation, and accepted as satisfactory.
This pay item shall include the cost of furnishing and installing
L-823 connector/splice kits, as needed, for connections in
manholes, to edge light i.l. transformers, and where needed for the
airfield lighting circuits. Separate measurement shall be made for
each cable or counterpoise wire installed in trench, duct bank or
conduit. The measurement for this item shall include quantities
required for slack.
Cable and counterpoise slack is considered incidental to this
pay item and shall be included in the as-bid per linear foot 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 counterpoise
installed by cable plowing, 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 ground connectors, wire connector/splice
kits, and trench marking tape, necessary to complete this item.
Payment will be made under the nomenclature and seven digits
item number specified (108xxxx) in the plans and specifications for
each size trench, type and size of insulated cable, and size of
counterpoise per linear foot.
Payment for trench sand backfill shall be made under the seven
digit item number 1527021, Misc. Trench Sand Backfill, at the
contract unit price for sand furnished and installed per cubic
yard.
MATERIAL AND TESTING REQUIREMENTS (Advisory Circular latest
edition)
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
AC 150/5340-30 Design and Installation Details for Airport
Visual Aids
AC 150/5345-53 Airport Lighting Equipment Certification
Program
FED SPEC A-A-55809 Insulation Tape, Electrical,
Pressure-Sensitive Adhesive, Plastic
FED SPEC A-A-59544 Specification of Electrical Wire and
Cable
ASTM B3 Soft or Annealed Copper Wire
ASTM B8 Standard Specification for Concentric-Lay-Stranded
Copper Conductors
ASTM B33 Standard Specification for Tin-Coated Soft or Annealed
Copper Wire
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
16
-
ASTM D4388 Rubber tapes, Nonmetallic Semi-Conducting and
Electrically Insulating
REFERENCE DOCUMENTS
NFPA -70 National Electrical Code (NEC)
NFPA-780 Standard for the Installation of Lightning Protection
Systems
MIL-S-23586F Sealing Compound, Electrical, Silicone Rubber
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
Item L-108 Underground Power Cable for Airports Approved by FAA
/ /
17
-
Michigan Department of Transportation Office of Aeronautics
Item L-109 Airport Transformer Vault and Vault Equipment
For NonPrimary Airports
DESCRIPTION
109-1.1 This item shall consist of constructing an airport
transformer vault (masonry or precast concrete construction) or a
prefabricated metal housing per these specifications in accordance
with the design, specifications, and dimensions shown in the plans
and contract documents. This work shall also include the
installation of conduits in the floor and foundation, painting and
lighting of the vault or metal housing, and the furnishing of all
incidentals that are necessary to produce a completed unit.
Included as a separate part under this item or as a separate item
where an existing vault is to be used shall be the furnishing of
all vault equipment, wiring, electrical buses, cable, conduit, high
voltage cable terminations, potheads, and grounding systems. This
work shall also include the painting of equipment and conduit; the
marking and labeling of equipment and the labeling or tagging of
wires; the testing of the installation; and the furnishing of all
incidentals necessary to place it in operating condition as a
completed unit to the satisfaction of the Engineer.
EQUIPMENT AND MATERIALS
109-2.1 General.
a. Airport lighting equipment and materials covered by Federal
Aviation Administration (FAA) specifications shall be certified and
listed under Advisory Circular (AC) 150/5345-53 (latest version),
Airport Lighting Equipment Certification Program.
b. All other equipment and materials covered by other referenced
specifications shall be subject to acceptance through manufacturers
certification of compliance with the applicable specification when
requested by the Engineer.
c. Manufacturers certifications shall not relieve the Contractor
of the Contractors responsibility to provide materials per 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 that comply with these specifications, at
the Contractors cost.
d. Documentation for all materials and equipment used to
construct this item shall be submitted to the Engineer for
acceptance prior to ordering the equipment. Five (5) sets of
Submittals consisting of marked catalog sheets or shop drawings
shall be provided. Accepted submittal distribution shall be:
One to Engineer
One to Owner
One to MDOT-AERO
Two to Contractor
If Contractor requires more than two returned sets, then
Contractor shall submit number of additional sets required.
109 Airport Transformer Vault and Vault Equipment Approved by
FAA / /
1
-
With approval of the Engineer, the Contractor can submit
material/equipment documentation electronically for review,
comment, and/or approval by the Engineer. At the Engineers option,
approved submittals can be scanned as pdf files and electronically
transmitted to the Contractor.
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 any 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 made
bold and clear with arrows or circles (highlighting is not
acceptable). The Contractor is solely responsible for delays in the
project that may accrue directly or indirectly from late
submissions, incomplete 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. It is recommended the Contractors submittals shall
be assembled and 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 Engineers opinion, does not meet the system design and the
standards and codes, specified in this document.
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 or workmanship
occurring within the twelve month period shall be repaired or
replaced, at the Owners discretion, with no additional cost to the
Owner.
CONSTRUCTION OF VAULT AND PREFABRICATED METAL HOUSING
109-2.2 General. The electrical vault shall be constructed at
the location, to the lines and dimensions, of the materials, and to
the specifications shown on the plans and in the contract
documents. If there is any variance between Specifications L-109
and the specifications shown in the plans and documents, the
specifications in the plans and documents shall take precedence. It
shall be responsibility of the Engineer to obtain FAA approval of
any variances from these L-109 specifications.
109-2.3 Concrete. The concrete for the vault shall be
proportioned, placed, and cured per Item P-610, Structural Portland
Cement Concrete, using 3/4 inch maximum size coarse aggregate or as
specified in the plans.
109-2.4 Reinforcing steel. Reinforcing steel bars shall be
intermediate or structural grade deformed-type bars and shall meet
the requirements of ASTM A615. Reinforcing steel size and layout
shall be as shown in the plans.
109-2.5 Brick. Brick shall conform to ASTM C62, Grade SW.
109-2.6 Rigid steel conduit. Rigid steel conduit and fittings
shall be per Underwriters Laboratories Standards 6 and 514. Conduit
diameter and layout shall be as shown in the plans.
109-2.7 Lighting. Vault or metal-housing light fixtures shall be
of a vapor-proof type.
109 Airport Transformer Vault and Vault Equipment Approved by
FAA / /
2
-
109-2.8 Outlets. Convenience outlets shall be heavy-duty duplex
units designed for industrial service. All outlets shall be GFCI or
the outlet circuit(s) shall be protected by a GFCI circuit
breaker.
109-2.9 Switches. Vault or metal-housing light switches shall be
single-pole switches.
All lightings, outlets, switches, and other miscellaneous vault
equipment (such as vents, heaters, etc.) shall meet the
specifications and layouts shown on the plans or in the contract
documents.
109-2.10 Paint.
a. Priming paint for non-galvanized metal surfaces shall be a
high solids alkyd primer conforming to TT-P-664D.
b. White paint for body and finish coats on metal and wood
surfaces shall be ready-mixed paint conforming to the Master
Painters Institute Reference #9, Exterior Alkyd, Gloss, VOC Range
E2.
c. Priming paint for wood surfaces shall be mixed on the job by
thinning the above specified white paint by adding 1/2 pint of raw
linseed oil to each gallon.
d. Paint and sealer for the floor, ceiling, and walls shall meet
the following specifications. Walls and ceiling shall be the color
specified in the plans, water repellant, low VOC(
-
109-2.16 Ground rods. Ground rods shall be copper or
copper-clad, not less than 8 feet long by 5/8 inch in diameter, or
of the length and diameter specified in the plans.
109-2.17 High Voltage Cable Termination. High voltage cable
termination shall be as specified in the plans or contract
documents and shall be as manufactured by Joslyn, Raychem, Siemens,
or approved equal. Cable terminations shall be furnished with plain
insulator bushings and conduit couplings. Cable terminations shall
have a rating not less than the circuit voltage.
109-2.18 Potheads. Potheads shall be similar to Gear and
Williams (G&W) Type N, Shape C (or equivalent), unless
otherwise specified. Potheads shall be furnished with plain
insulator bushings and conduit couplings. Potheads shall have a
rating not less than the circuit voltage.
109-2.19 Prefabricated Vault prefabricated metal housing. The
prefabricated metal housing shall be a commercially available
unit.
109-2.20 FAA-approved equipment. Certain items of airport
lighting equipment installed in vaults are covered by individual
FAA equipment specifications. All equipment must be certified by
the FAA and listed under Advisory Circular (AC) 150/5345-53 (latest
version), Airport Lighting Equipment Certification Program. The
specifications are listed below (note the latest AC edition in
applicable).
AC 150/5345-3 Specification L-821, Panels for Remote Control of
Airport Lighting
AC 150/5345-5 Specification for Circuit Selector Switch
AC 150/5345-7 Specification L-824 Underground Electrical Cable
for Airport Lighting Circuits
AC 150/5345-10 Specification L-828, Constant Current Regulators
and Regulator Monitors
AC 150/5345-13 Specification, L-841, Auxiliary Relay Cabinet
Assembly for Pilot Control of Airport Lighting Circuits.
AC 150/5345-49 Specification L-854, Radio Control Equipment
AC 150/5345-56 Specification L-890, Airport Lighting Control and
Monitoring Systems (ALCMS)
109-2.21 Other electrical equipment. Distribution transformers,
oil switches, cutouts, relays, terminal blocks, transfer relays,
circuit breakers, and all other regularly used commercial items of
electrical equipment not covered by FAA equipment specifications
shall conform to the applicable rulings and standards of the
Institute of Electrical and Electronic Engineers or the National
Electrical Manufacturers Association. When specified, test reports
from a testing laboratory indicating that the equipment meets the
specifications shall be supplied. In all cases, equipment shall be
new and a first-grade product. This equipment shall be supplied in
the quantities required for the specific project and shall
incorporate the electrical and mechanical characteristics specified
in the proposal and plans. Equipment selected and installed by the
Contractor shall maintain the interrupting current rating of the
existing systems or specified rating whichever is greater.
109 Airport Transformer Vault and Vault Equipment Approved by
FAA / /
4
http:109-2.21http:109-2.20http:109-2.19http:109-2.18http:109-2.17http:109-2.16
-
109-2.22 Wire. Interior vault wiring for wire in conduit rated
up to 5,000 volts shall conform to AC 150/5345-7, Specification for
L-824 Underground Electrical Cables for Airport Lighting Circuits,
Type B or C. For wire ratings up to 600 volts, moisture and heat
resistant thermoplastic wire conforming to Fed. Spec. A-A-59544,
Types THW, THWN, and Type THWN-2 shall be used. The wires shall be
of the type, size, number of conductors, and voltage shown in the
plans or in the proposal.
a. Control circuits. Control circuits are defined as those
circuits transmitting low voltage (such as 120v AC, 12/24v DC, or
optical signal) from a control point (typically a control panel in
the ATCT or airport managers office in the terminal building) to
airfield lighting equipment located remote from the control panel
for the express purpose of activating or deactivating the
equipment.
Unless otherwise indicated on the plans, control wire shall be
not less than No. 12 AWG and shall be insulated for 600 volts. If
telephone control cable is specified, No. 19 AWG telephone cable
conforming to ICEA S-85-625-20007 specifications shall be used. If
fiber optic wire is specified, it shall be as specified in the
plans.
b. Power circuits. Power circuits are defined as those circuits
providing constant voltage to or through equipment that sends the
operating voltage to a point of utilization (such as constant
current regulator, wind cone, PAPI system, etc.). Power cable
within the electrical vault shall meet the following
specifications:
(1) 600 volts maximum-Wire shall be No. 6 AWG or larger and
insulated for at least 600 volts, or greater as sized and rated in
the plans.
(2) 3,000 volts maximum-Wire shall be No. 6 AWG or larger and
insulated for at least 3,000 volts, or greater as sized and rated
in the plans.
(3) Over 3,000 volts-Wire shall be No. 6 AWG or larger and
insulated for at least the circuit voltage, or greater as sized and
rated in the plans.
109-2.23 Short circuit / coordination / device evaluation / arc
flash analysis. The Contractor shall, based upon the equipment
provided, include as a part of the submittal process the electrical
system Short Circuit / Coordination / Device evaluation / Arc Flash
Analysis. The analysis shall be performed by the equipment
manufacturer and submitted in a written report. The analysis shall
be signed and sealed by a registered professional Engineer from the
state in which the project is located. The analysis shall comply
with NFPA-70E and IEEE 1584. The analysis will include: one line
diagrams, short circuit analysis, coordination analysis, equipment
evaluation, arc flash analysis and arc flash labels containing at a
minimum, equipment name, voltage/current rating, available incident
energy and flash protection boundary.
The selected firms field service Engineer shall perform data
gathering for analysis completion and device settings, perform
device setting as recommended by the analysis and will furnish and
install the arc flash labels. The components worst case incident
energy will be considered the available arc flash energy at that
specific point in the system. Submit three written copies and one
electronic copy of the report.
CONSTRUCTION METHODS
CONSTRUCTION OF VAULT AND PREFABRICATED METAL HOUSING
109-3.1 General. The Contractor shall construct the transformer
vault or prefabricated metal housing at the location indicated in
the plans. Vault construction shall be prefabricated metal housing,
reinforced
109 Airport Transformer Vault and Vault Equipment Approved by
FAA / /
5
http:109-2.23http:109-2.22
-
concrete, concrete masonry, or brick wall as specified on the
plans or in the contract documents. Vault structures shall meet
wind and snow loads as specified by the Engineer.
The Contractor shall clear, grade, and seed the area around the
vault or metal housing for a minimum distance of 10 feet on all
sides. The slope shall be not less than 1/2 inch per foot away from
the vault or metal housing in all directions.
The vault shall provide adequate protection against weather
elements, including rain, wind-driven dust, snow, ice and excessive
heat. The vault shall have sufficient filtered ventilation (MERV
8), to assure that the interior room temperatures and conditions do
not exceed the recommended limits of the electrical equipment to be
installed in the vault. The Contractor is responsible for
contacting the manufacturer of the equipment to be installed to
obtain environmental limitations of the equipment to be
installed.
The vault, including its venting and environmental controls
(heating/cooling), shall be as specified on the plans or in the
contract documents. Refer to the electrical vault detail plan
sheets for construction requirements. The prefabricated building
shall include roof, walls and floor in accordance with the details
and these specifications.
109-3.2 Prefabricated Metal Housing. If a metal housing, it
shall be a prefabricated equipment enclosure to be supplied in the
size specified. The mounting pad and floor details, installation
methods, and equipment placement shall be as shown in the
plans.
109-3.3 Foundation and walls.
a. Reinforced concrete construction. The Contractor shall
construct the foundation and walls per the details shown in the
plans. Unless otherwise specified, internal ties shall be of the
mechanical type so that when the forms are removed the ends of the
ties shall be at least 1 inch beneath the concrete surface; the
holes shall be plugged and finished to prevent discoloration.
Reinforcing steel shall be placed, as shown in the drawings, and
secured in position to prevent displacement during the concrete
placement.
The external surfaces of the concrete shall be thoroughly worked
during the placing operation to force all coarse aggregate from the
surface. Thoroughly work the mortar against the forms to produce a
smooth finish free from air pockets and honeycomb.
The surface film of all pointed surfaces shall be removed before
setting occurs. As soon as the pointing has set sufficiently, the
entire surface inside and outside of the vault shall be thoroughly
wet with water and rubbed with a No. 16 carborundum stone, or
equivalent quality abrasive, bringing the surface to a paste. All
form marks and projections shall be removed. The surface produced
shall be smooth and dense without pits or irregularities. The
materials which have been ground into a paste during the rubbing
process shall be spread or brushed uniformly over the entire
surface (except the interior surfaces that are to be painted shall
have all paste removed by washing before painting) and permitted to
reset. Final exterior finish shall be obtained by rubbing with No.
30 carborundum stone, or an equivalent quality abrasive. The
surface shall be rubbed until the entire surface is smooth and
uniform in color.
b. Brick and concrete construction. When this type of
construction is specified, the foundation shall be concrete
conforming to the details shown in the plans. The outer edge of the
foundation at the floor level shall be beveled 1-1/2 inches at 45
degrees. Brick walls shall be 8 inches thick, laid in running bond
with every sixth course a header course. Brick shall be laid in
cement mortar (1 part masonry cement and 3 parts sand) with full
mortar bed and shoved joints. All joints shall be completely filled
with mortar, and facing brick shall be back-parged with mortar as
work progresses. All joints shall be 3/8 inch thick, exterior
joints tooled concave, and interior joints struck flush. Both
interior and exterior brick surfaces shall be cleaned and nail
holes, cracks and other defects filled with mortar. Steel
reinforcing bars, 109 Airport Transformer Vault and Vault Equipment
Approved by FAA / /
6
-
3/8 inch in diameter and 12 inches long, shall be set vertically
in the center of the brick wall on not more than 2 feet centers to
project 2-1/2 inches into the concrete roof slab. Lintels for
supporting the brickwork over doors, and louvers shall consist of
two 4 3 3/8 inch steel angles. Lintels shall be painted with one
coat of corrosion-inhibiting primer before installation, and all
exposed parts shall be painted similar to doors after
installation.
All exposed surfaces shall have a rubbed finish as specified
under reinforced concrete construction. After completion, all
interior and exterior faces of walls shall be scrubbed with a
solution of muriatic acid and water in the proportions of not less
than 1 part acid to 10 parts of water. All traces of efflorescence,
loose mortar, and mortar stain shall be removed, and the walls
washed down with clear water.
c. Concrete masonry construction. When this type of construction
is specified, the foundation shall be concrete conforming to the
details shown in the plans. The concrete masonry units shall be
standard sizes and shapes and shall conform to ASTM C90 and shall
include the closures, jambs, and other shapes required by the
construction as shown in the plans. Standard construction practice
shall be followed for this type of work including mortar, joints,
reinforcing steel for extensions into roof slab, etc. Plaster for
interior walls, if specified, shall be Portland cement plaster.
d. Precast Concrete Construction. When a precast concrete vault
is specified, the site or preparation shall be as specified in the
plans or, if not specified, in accordance with 109-3.5.
Vault site shall be stabilized with, as a minimum, a 6 inch deep
base extending 6 inches outside exterior vault walls, using 1 inch
maximum limestone aggregate.
The precast concrete vault shall be of the dimensions specified
in the plans and, as a minimum, consist of 4 inch thick walls, 4
inch thick ceiling/roof, and 6 inch thick floor all constructed of
5,000 psi concrete at 28 days. Reinforcing bars shall be Grade 60.
Vault shall have a fire rating of at least 1 1/2 hours.
Vault exterior finish shall be as specified in the plans or, if
not specified, exterior shall be exposed aggregate finish.
Doors shall be in accordance with specifications contained in
the plans or, if not specified, shall meet the requirements of
L-109-3.8.
The precast vault shall be furnished with vent(s), window(s),
and other accessories as specified on the plans.
Precast concrete vault shall be as manufactured by Advanced
Concrete Products (advanceconcreteproducts.com), Quality Precast,
Inc. (qualityprecastinc.com), or approved equal.
All conduits, ducts, and electrical structures exterior to the
vault, and either terminating at/in the vault and within the vault
site can be installed pre- or post-building erection, as approved
by the Engineer.
109-3.4 Roof. If specified in the plans and contract documents,
The roof for a site-built electrical vault (does not include
precast vault buildings) shall be reinforced concrete. Reinforcing
steel shall be placed as shown in the drawing and secured in
position to prevent displacement during the pouring of the
concrete. The concrete shall be poured monolithically and shall be
free of honeycombs and voids. The surface shall have a
steel-tro