SPECIFICATIONS FOR OVERHEAD DISTRIBUTION LINE CONSTRUCTION
12.5/7.2 kv line construction shall conform to Rural Utility Service (RUS) Bulletin Form-804 Specifications
and Drawings (http://www.usda.gov/rus/electric/bulletins.htm), with supplementary requirements as
specified below. Special notations are used in this specification as follows:
(*) See RUS Bulletin (Items 1 thru 17) for omitted text usually referring to construction not
commonly used in distribution installations (e.g. setting poles in solid rock, etc.)
BOLD Amendments to RUS specification.
Italic: Supplement to RUS specification.
All construction work shall be done, in a through and workmanship manner, in accordance with
staking sheets, plans and specifications, and construction drawings.
The latest edition of the NATIONAL ELECTRICAL SAFETY CODE (NESC ANSI C2) shall be
followed except where local regulations are more stringent, in which case local regulations shall
2. Distribution of poles:
In distributing the poles, large, choice, close-grained poles shall be used for transformer, dead-
end, angle and corner poles.
3. Pole Setting:
All poles shall be set to RUS specifications plus one foot. The minimum depth for setting poles
shall be as follows:
Length of Setting in
Pole (Feet) Soil (feet)____
20 4.0 + 1.0 = 5.0
25 5.0 + 1.0 = 6.0
30 5.5 + 1.0 = 6.5
35 6.0 + 1.0 = 7.0
40 6.0 + 1.0 = 7.0
45 6.5 + 1.0 = 7.5
50 7.0 + 1.0 = 8.0
On sloping ground, the depth of the hole shall be measured from the low side of the hole.
Poles shall be set so that alternate crossarm gains face in opposite directions, except at terminals
and dead-ends where the gains of the last two poles shall be on the side facing the terminal or
dead-end. On unusually long spans, the poles shall be set so that the crossarm comes on the side
of the pole away from the long span. Where pole top pins are used, they shall be on the opposite
side of the pole from the gain with the flat side against the pole.
Poles shall be in alignment and plumb except at corners, terminals, angles, junctions so that other
points of strain, where they shall be set and raked against the strain so that the conductors shall be
in line. Vertical angle structures (A3, B3, C3) shall be offset from the centerline to prevent the
adjacent poles from leaning in to the angle.
1 of 7 (MS rev. 9/26/07)
Poles shall be raked against the conductor strain not less than one inch for each the feet of pole
length after conductors are installed at the required tension.
Pole backfill shall be thoroughly tamped the full depth. Excess dirt shall be banked around the pole
4. Grading of line:
When using high poles to clear obstacles such as buildings, foreign wire crossings, railroads, etc.,
there shall be no up strain on pin-type (*) insulators in grading the line each way to lower poles.
5. Guys and Anchors:
Guys shall be placed before the conductors are strung. And shall be attached to the poles as
shown on the construction drawings.
All anchors and rods shall be in line with the strain and shall be so installed that approximately six
inches of rod remain out of the ground. In cultivated fields or other locations deemed necessary,
the projection of the anchor rod above the earth may be increased to a maximum of 12 inches to
prevent the burial of the rod eye. The backfill of all anchor holes must be thoroughly tamped the full
Guy bonding clamps shall be installed in the eyes of all anchor rods. All guys (primary and
secondary) shall be effectively grounded according to RUS specifications. On secondary poles,
guys shall be grounded to the secondary neutral.
All anchor shall consist of 24 inch later anchors buried to the proper depth in line with the strain. A
1:1 guy leas shall be provided (i.e. 28 foot to 30 foot’) where ever possible with a minimum
allowable lead of 20 feet unless otherwise specified.
Locknut shall be installed with each nut. Eyenut or other fastener on bolts or other threaded
hardware such as insulated pins, upset bolts, double arming bolts, etc.
Conductors shall be handled with care. Conductors shall be trampled on nor run over by vehicles.
Each real shall be examined and the wire shall be inspected for cuts kinks and other injuries.
Injured portions shall be cut out and the conductor spliced. The conductors shall be run over roller
or stringing blocks properly mounted on pole or crossarm if necessary to prevent binding while
` The neutral conductor shall be installed on the roads side of the pole for tangent
construction and for angles not exceeding 30 degrees.
With pin-type (*) insulators, armor rod shall be installed on the conductor and the conductors shall
be tied in the top grove of the insulator on tangent poles and on the side of the insulator away from
the strain at angles. Pin-type (*) insulators on tangent construction shall be tight on the pins (*)
and on tangent construction the top groove must be in line with the conductor after tying.
For line angles 0 to 5 degrees in locations known to be subject to considerable conductor vibration,
insulated brackets (material item “da”) may be substituted for the single and double upset bolts
used for supporting the neutral and secondary conductors.
2 of 7 (MS rev. 9/26/07)
All conductors shall be cleaned througherly by wiring brushing before splicing and installing
conductors or camps. A suitable inhibitor shall be used before splicing or applying connectors over
All scrap conductors shall be discarded properly. All excess material shall be returned to the plant.
8. Splices and dead-ends:
Conductors must be spiced and dead-ended as shown on the construction drawings. There shall
not be more than one splice per conductor in any span and splicing sleeves shall be located at
least ten feet from the conductor support. No splices shall be located in grade B crossing spans
and preferably not in adjacent spans. Splices shall be installed in accordance with the
9. Taps & jumpers:
Jumpers and other lads connected to line conductors shall have sufficient slack to allow free
movement of the conductors. Where slack is not shown on the construction drawings it will be
provided by at least two (2) bends in the vertical plane, or one (1) in a horizontal plane, or the
equivalent. In areas where Aeolian vibration occurs, special measures to minimize the effects of
the jumper breaks shall be used as specified.
All leas on equipment such as transformers, reclosers, etc. shall be a minimum #6 copper
conductivity. Where aluminum conductors are used, a connection to an unplated bronze terminal
shall be made by splicing a short stub of copper the aluminum jumper using a suitable aluminum
(!) Preformed spiral vibration dampers shall be installed on the mainline primary where the
taps are made to sectionalizing cutouts and transformers.
(!) All primary jumpering shall consist of #2 ACSR.
(!) Top tap assembles shall be framed so that the source is on the top and the load (tap) is
below. In no case shall pin type insulators be installed upside down to carry jumpers.
10. Hot-line connectors and connections:
Connectors and hot-line clamps suitable for the purpose shall be installed as shown on the
guide drawings. On al hot-line clamp installations, the clamp and jumper shall be installed
so that they are permanently bonded to the load side of the line allowing the jumper to be
de-energized when the clamp is disconnected.
Hot-tap clamps shall not be used to connect a URD feeder source to the overhead distribution
lines, such as plant riser poles. Compression connectors shall be used in these circumstances.
Hot line clamps shall be installed over line guards (armor rods).
(!) Use Aluminum main to aluminum tap rated connectors for ACSR jumping.
All insulated secondary to secondary connections shall be made using compression connectors
witch are pre-insulated or parallel grove connectors with plastic covers.
Secondary connections at pole-mounted transformers shall be made up using compression pigtails
on the end of each conductor, sand then installed in a stud bushing of the transformer. Inhibitor
compound shall be used in all the mechanical (set screw) connections.
3 of 7 (MS rev. 9/26/07)
11. Surge Arrestors:
(*) Surge arrestors are generally not used in Alaska villages where lighting strikes are rare
12. Conductor ties:
(*) Ties shall be in accordance with construction drawings and applied per manufactures’
recommendations. Hot-line ties shall not be used in grade “B” crossings.
All primary ties shall be factory-formed type.
(!) Armor rod shall be installed on all primary and neutral ACSR conductors, attached to pins.
13. Sagging of Conductors:
Conductors shall be sagged in accordance with the conductor’s recommendations. All conductors
shall be sagged evenly. The air temperature sat the time shall be determined by a certified etched
The sag of all conductors after stringing shall be in accordance with the conductor
manufacturer’s recommendations, except that the maximum increase of three inches of the
specified sage in any span will be acceptable. However, under no circumstances will a
decrease in the specified sag be allowed.
Maximum unbalanced conductor tension on dead-end crossarm assemblies, such as A7, B7, and
C7is 1,000 lbs./conductor, or 1,500 lbs/conductor for A7-1, B7-1 and C7-1 assemblies.
14. Secondaries and service drops:
Secondary conductors shall be (*) multi-conductor service cable. The conductors shall be sagged
in accordance with the manufacturer’s recommendations.
Conductors for secondary underbuild on primary lines shall be insulated in those instances where
prevailing conditions may limit primary span lengths to the extent that covered wires or service
cables may be used. Service drops shall be covered wire or service cable.
Secondary and service drops shall be installed so as not to obstruct climbing space. There shall
not be more than one splice per conductor in any span, and splicing sleeves shall be located at
least ten feet from the conductor support. Where the same covered conductors or service cables
are to be used for the secondary and service drop, thy may be installed in one continuous run.
#4 Service drops over 140 feet in length shall be solidly guyed.
#2 Service drops over 100 feet in length shall be solidly guyed.
Install a wrap of tape around multi-plex cable at ends to prevent further unraveling. Where multi-
plex cable is open-ended, fold leads back and tape to mainline. Also tape the rough edges of
preformed grips to protect the insulated leads from abrasion caused by wing vibration
Unless otherwise noted #4 triples may be used to service 125 amp entrances utilizing #2 copper;
#2 triples should be used to service 150-200 amp entrances utilizing #2/0 copper; #1/0 triplex
should be considered for service to 200-amp entrances utilizing large resistive cooking equipment
or large resistive heaters and cloths dryers.
Secondary cables shall be installed: 16” below existing bare neutral and 4’-10” down on poles
intended for future primary tangent or 6’-1” down on poles intended for future primary dead-end.
4 of 7 (MS rev. 9/26/07)
Where both 240/120 volt one-phase and higher voltage (208 or 480 volt) 3-phase secondary are to
be installed, the higher voltage circuit shall be attached at least 16” above the lower voltage circuit
(up to 4/0 quadruplex over 1/0 triplex, 200-feet maximum span.).
Ground rods shall be driven full length in undistributed earth in accordance with
construction drawings. The top shall be at least 12” below the surface of the earth. The
ground wire shall be attached to the rod with a clamp and secured to the pole with staples.
The staples on the ground wire shall be spaced two feet apart and down eight feet down
from the top of the pole. where they shall be six inches apart.
All equipment shall have at least two conductors from the frame, case or tank to the multi-
grounded neutral conductor.
The equipment ground, neutral wires and any lighting-protective equipment shall be
interconnected and attached to a common ground wire.
The primary neutral shall have a ground connection at least every 1,320 feet/ 402 meters, and
preferably every 1,056 feet/322 meters. (Reference REA Bulletin 83-1 Adequate Grounding on
Primary Distribution Lines (March 1977))
16. Clearing Right of Way:
(*) Not generally required in Alaska villages.
17. Structures Exceeding 200 feet in Height and Structures in the Vicinity of Airports:
(See Federal Aviation Administration Regulation Part 77 – Objects Affecting Navigable
Airspace January 1975)
Polemount transformers shall conform to AVEC Specifications for Single-Phase Stainless Steel
Polemount Transformers dated July 7, 2005, and be installed and grounded according to RUS
specifications. Transformers shall have at least two connections from the tank to the multi-
grounded neutral conductor.
All transformers will be CSP-type not requiring cutouts. Ensure that warning light covers & bulbs on
the CSP transformers are not broken and replace if necessary.
Insulated trainer brackets (material “fo”) shall be used at pole transformers to secure secondary
cable leads to prevent chafing due to wind movement.
Transformers internally wired for 102 volt secondary (Ref G312 Specification) shall be labels
“120V” with reflective tags, Lettering height 2 -1/2” minimum height.
(!) Use a contrasting sized pin insulator for supporting the neutral on an A9, A9-1, B9, B9-1,
assemblies to differentiate the neutral. Use ANSI class 55-3 insulator for the neutral.
25kv class insulators and terminators shall be used for coastal villages subject to wind-
driven salt spray and dust combination.
5 of 7 (MS rev. 9/26/07)
20. Pole Risers (See URD specifications):
Unistrut™ standoff brackets shall be used on all riser poles to attach the riser conduit to the pole.
The first ten feet (from 30”-> 36” above grade) of all risers shall be galvanized rigid steel conduit
(GRSC). Schedule-40 Polyvinyl Chloride (PVC) conduit may be used for the remaining length
above the GRSC. A 10-foot section of liquid tight flexible metal conduit (LTFMC) shall extends from
the bottom of the GRSC from 30” -> 36” above the grade into the ground, with a slack “Goose-
neck” bend above grade to allow for pole frost heaving.
The distance between the lowest standoff bracket and the next bracket up, must be a
minimum of 8 feet to meet NESC rule 217A2c.
All liquid-tight flexible metal conduit (LTFMC) shall be terminated with insulated-throat bushings
and properly grounded according to specification drawings.
22. Phasing Convention:
Multi-phase riser cables shall be color coded at the terminators to indicate corresponding phase at
the URD source/load as applicable, as follows: A-phase = Red; B-phase = Blue: C-phase = Yellow.
Distribution A-Phase shall always be at the top or at the extreme left, when viewed facing the load,
with the power source at your back.
Service entrance to be provided by the consumer.
Service entrance wiring shall be #2 AWG copper for 100->125 Amp services with a #6 AWG
copper ground; #2/0 AWG copper for 150->200 Amp service with a #2 AWG ground. At least 18”
wire tails shall e provided for connection to the utility system with the neutral clearly identified. The
meter base shall be mounted 5-foot minimum / 6-foot maximum above grade. 2” GRSC or IMC
shall be extended 3’ – 6” above the roof line to the weatherhead on the gable end of the house.
(See Service Entrance drawing for details)
Conversion of URD to overhead service:
#2 AWG copper shall be used to convert all services with 125-amp or smaller main breakers. #2/0
AWG copper shall be used to convert all services to services with 150->200 main circuit breakers.
The conduit riser shall be installed such that the service entrance wires are totally contained within
the sealed utility compartment and inaccessible to the consumer (to prevent power theft). Ensure
the service entrance equipment is bonded in accordance with the National Electric Code (NEC)
sections 250.26 and 250.28.
Conduit fittings other than threaded hubs (e.g. entrance ells) shall use approved bonding fitting.
24. Intermediate Masts:
In villages where large snow drifts occur, a 2” Intermediate metal Conduit (IMC) intermediate
support mast shall be installed at the peak or highest point of the structure to elevate the service
drops over the snow drifts. The incoming service drop shall be attached to this mast before
dropping to the service mast. Service lines at maximum loading shall be maintained at least 3-feet
above the roof and at least 10 feet above grade with snow drifts. The Intermediate mast shall be
6 of 7 (MS rev. 9/26/07)
solidly attached to the structure with conduit straps every 12 inches. A cap shall be installed at the
top end of the conduit. Penetrations through the roof shall be made with Dektight roof jacks and
sealed with silicon caulking to prevent leakage. Two service clevises shall be used on the
intermediate mast if the angle between the incoming and outgoing service lines is greater than 45 .
URD cable shall be spliced to the consumer wires five (5) feet below grade for all 100->200 Amp
services to buildings. URD cable may be terminated directly to the consumer meter base lugs only
for pole/post, or similar mounted service entrance not attached to the building.
7 of 7 (MS rev. 9/26/07)