Art. 806.03 Underground Raceways Testing resistance to ground shall be according to Article 801.13(a)(5). If the measured resistance to ground exceeds 10 ohms, additional rods shall be added to the grounding electrode. A maximum number of three rods shall be coupled together. If coupling three rods together does not lower the resistance to 10 ohms, then additional grounding electrodes shall be installed, a minimum of 6 ft (1.8 m) from each other and the initial installation and connected by a grounding electrode conductor to form a ground field. If the resistance to ground still exceeds 10 ohms after three sets of three coupled electrodes have been installed in the ground field or where sub-surface conditions limit the depth to which the grounding electrode(s) can be installed, the Contractor shall contact the Engineer for further instructions.
806.04 Basis of Payment. Installation and testing of the first rod for the
grounding electrode will not be paid for separately, but shall be included in the cost of the item for which it is installed. If additional rods are needed, their installation and testing will be paid for according to Article 109.04. WIREWAY AND CONDUIT SYSTEMS SECTION 810. UNDERGROUND RACEWAYS
810.01 Description. This work shall consist of furnishing and installing
conduit, fittings and accessories as part of raceway either laid in trench, bored and pulled in place, or encased in concrete.
810.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Rigid Metal Conduit ....................................................................... 1088.01(a)
b.Rigid Nonmetallic Conduit ............................................................. 1088.01(b)
c.Coilable Nonmetallic Conduit .......................................................... 1088.01(c)
d.Portland Cement Concrete (Note 1) ....................................................... 1020
e.Underground Cable Marking Tape ..................................................... 1066.05
f.Fine Aggregate .................................................................................. 1003.04
g.Reinforcement Bars .................................................................................. 508 Note 1. Class SI concrete shall be used for encased conduit.
810.03 Equipment. Equipment shall be according to the following.
Item Article/Section
a.Cable Plow (Note 1)
b.Auger (Note 2) Note 1. The plow shall be capable of plowing a cavity and placing the conduit to the specified depth in a single operation without kinking or otherwise damaging the conduit. Note 2. The auger shall be a remotely steerable, fluid cutting tunneling system. The tunneling system shall be electronically detectable and shall line the tunnel with a clay lining as it tunnels. Underground Raceways Art. 810.04 CONSTRUCTION REQUIREMENTS
810.04 Installation. Underground conduit shall be installed at a depth of 24
to 30 in. (600 to 750 mm) below the finished grade and shall be installed to avoid existing and proposed utilities within the project limits. At the Contractor’s option, conduit shall be installed by trenching, plowing, or boring and pulling; except boring and pulling will be required under pavement, stabilized shoulder, paved median, paved driveway, curb, gutter, curb and gutter, or sidewalk. Areas disturbed by the following operations shall be restored to their original conditions as directed by the Engineer.
a.Trenching. Trenches shall not exceed 1 ft (300 mm) in width without prior approval of the Engineer. The trenches shall be constructed to permit easy installation of conduit without twisting, kinks, or sharp bends. The bottom of the trench shall be built up with suitable compacted backfill material so the conduit will have a smooth bed. Where separate circuit runs are to be installed parallel with each other, one common trench shall be used. At the locations where a trench crosses other existing cable systems, the trench shall be hand dug 6.5 ft (2 m) to either side of the crossing. Backfill material shall be free of brick, rock, or any material that could damage the conduit. Backfill material for trenches in the subgrade of the proposed improvement, and for trenches outside of the subgrade where the inner edge of the trench is within 2 ft (600 mm) of the edge of the proposed pavement, curb, gutter, curb and gutter, stabilized shoulder, or sidewalk shall be trench backfill. Backfill shall be deposited in uniform lifts not exceeding 6 in. (150 mm) thick loose measure. The material in each lift shall be mechanically compacted by tamping with power tools approved by the Engineer in such a manner as not to disturb or damage the conduit. Disposal of surplus material shall be according to Article 202.03. Underground cable marking tape shall be installed a minimum of 6 in. (150 mm) and not more than 1 ft (300 mm) below finished grade for all underground conduit runs. When fiber optic cable is to be placed in the conduit, an underground cable marking tape with a metallic detection strip shall be used. Splicing of the tape shall be accomplished with metal clips to maintain electrical continuity along the entire length of the tape. Splices shall be wrapped with a waterproof adhesive tape.
b.Plowing. The conduit shall be round and free of kinks when fed into the plow and placed in the ground. Pulling of the conduit within the plowed Art. 810.05 Underground Raceways cavity will not be allowed. When more than one conduit is placed into a single plowed cavity, they shall be free of twists. Where another circuit is plowed in parallel to the first, the distance between the two shall be not less than 1 ft (300 mm) nor more than 2 ft (600 mm). Underground cable marking tape shall be installed according to
Article 810 — 04(a).
c.Boring and Pulling. Conduit shall be installed with the use of an auger. Conduit in the subgrade of the proposed improvement shall extend a minimum of 2 ft (600 mm) beyond the edge of the proposed pavement, stabilized shoulder, paved median, paved driveway, curb, gutter, curb and gutter, or sidewalk.
810.05 Conduit Assembly. Conduit assemblies shall be according to the
following.
a.Rigid Metal Conduit (Steel, Intermediate Metal, Aluminum). The ends of the conduit shall be cut square and thoroughly reamed before installation. All burrs and rough edges shall be removed. Bends shall be made with a standard pipe bender. Bends shall be made so the conduit is not damaged and the internal diameter of the conduit is not effectively reduced. Conduit joints shall be threaded. All joints before assembly and exposed threads after assembly shall be coated with low resistance, conductive, joint compound. Running threads in conduit runs will not be permitted. Conduits shall not be over-threaded. The protective coatings on all threads must be sufficient to prevent corrosion before installation is made. If threads become corroded before installation, the material shall be replaced with new material or the corroded parts thoroughly cleaned and recoated as directed by the Engineer. Ends of conduits shall be equipped with insulating bushings. Rigid metal conduits terminating in the base of lighting controllers, pedestal bases, transformer bases, and other open enclosures shall be equipped with insulating bushings with ground lugs. The ground lugs shall be used to bond the conduits to the enclosure via a copper grounding conductor. Conduits terminating at cast or malleable iron boxes shall be terminated in conduit hubs. Hubs shall be integral to the box or installed separately. Non- integral hubs or integral hubs which do not provide a flared, smooth entry shall not be used and in these cases two locknuts and an insulating bushing shall be used. Threaded conduits shall terminate with two locknuts and an insulating bushing for sheet metal enclosures above grade. Conduit connections shall be made tight to ensure good grounding continuity. Underground Raceways Art. 810.05 Conduit below pavement, used as sleeves, shall extend a minimum of 2 ft (600 mm) beyond the shoulder, curb, and/or guardrail. The conduit shall be cleaned by rodding and swabbing to remove all dirt and other foreign materials and capped until conductors are installed.
b.Rigid Nonmetallic Conduit. The conduit shall be cut square. All burrs shall be removed from the inside and outside of the conduit. Bending of the conduit shall be made so the conduit will not be damaged and the internal diameter of the conduit will not be effectively reduced. Bends shall be made with standard pipe bending equipment for nonmetallic conduit. The conduit section shall be heated evenly over the entire length of the bend. The use of torches or other flame-type devices will not be allowed. Sections showing evidence of scorching or discoloration will not be acceptable. All joints shall be test mated without forcing, then cemented. The socket depth of the fitting shall be marked on the outside of the conduit without scratching or damaging the surface. The conduit shall enter the fitting for the full depth of the socket. Before applying cement, the surfaces to be joined shall be wiped clean and free of dirt, oil, grease, or moisture. The solvent cement shall be applied according to manufacturer’s recommendations. Immediately after applying the coat of cement to the conduit and fittings, the conduit shall be inserted into the fitting socket until it bottoms at the fitting shoulder. The conduit shall be turned 1/4 turn during insertion to distribute the cement evenly. Excess cement shall be wiped away from the outside of the joint. Newly assembled joints shall set a minimum of ten minutes before handling.
c.Coilable Nonmetallic Conduit. Coilable nonmetallic conduit shall be installed in continuous lengths, without splicing. Conduit extended to lighting, traffic, and sign structures shall extend 12 in. (300 mm) above the base of the structure. Bends of conduit shall be made manually so the duct will not be damaged and the internal diameter of the duct will not be effectively reduced. No more than the equivalent of four quarter bends (360 degrees total) shall be made between termination/pull points.
d.Concrete-Encased Conduit. Multiple conduit runs grouped together in a duct bank shall be encased in Class SI concrete and shall be supported on interlocking plastic spacers designed for the purpose, spaced along the length of the run as recommended by the manufacturer. Spacing between Art. 810.05 Exposed Raceways raceways within a common duct bank shall be a minimum of 2 in. (50 mm). The interlocking spacers shall be used at a maximum interval of 5 ft (1.5 m). Concrete cover overall shall be a minimum of 3 in. (75 mm) all around the encased run. During concrete placement there shall be no voids, the spacers shall be undisturbed, and the conduit joints shall stay secure and unbroken. Concrete shall be deflected during placement to minimize the possible damage to or movement of the conduits. Conduit encased in concrete shall have steel reinforcing when installed below roadway or other paved vehicle areas (including shoulder) and the reinforcement shall extend a minimum of 5 ft (1.5 m) additional from the edge of pavement. Steel reinforcement shall be a minimum of No. 4 (No. 15) bars at corners and otherwise spaced on 12 in. (300 mm) centers, tied with No. 4 (No. 15) bars on 12 in. (300 mm) centers. All conduit joints and supports shall be inspected and approved by the Engineer before concrete is poured.
810.06 Method of Measurement. This work will be measured for payment in
feet (meters) in place. Measurements will be made in straight lines along the centerline of the conduit between ends and changes in direction. Vertical conduit will be measured for payment. The vertical distance required for breakaway devices, barrier wall, concrete pedestals, etc., and the depth of any burial will be measured. Changes in direction shall assume perfect straight line runs, ignoring actual raceway sweeps.
810.07 Basis of Payment. This work will be paid for at the contract unit price
per foot (meter) for UNDERGROUND CONDUIT, of the type and size specified. Conduit encased in concrete will be paid for at the contract unit price per foot (meter) for CONDUIT ENCASED, of the type, diameter, and number of raceways wide by the number of raceways high specified. Reinforcement bars will not be paid for separately. SECTION 811. EXPOSED RACEWAYS
811.01 Description. This work shall consist of furnishing and installing
raceways, fittings, and accessories attached to supports.
811.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Rigid Metal Conduit ....................................................................... 1088.01(a)
b.Expansion Fittings for Raceways ....................................................... 1088.02
c.Stainless Steel Junction Box ......................................................... 1088.04(a)
d.Fasteners and Hardware ................................................................... 1088.03 CONSTRUCTION REQUIREMENTS
Referenced in this section
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 701–705 of 1,217. View official source ↗