901.10 Preparation of Plans

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901.10.1 Scale

Scales of 1" = 50' or 1" = 100' are preferred. However, if reproductions of the road plans are used, any scale is acceptable. A graphic scale is shown on each sheet.

901.10.2 Topography

Features affecting lighting design, such as entrances and approaches, pavement layout, existing pole lines, existing lighting fixtures, kind of lamps, and proposed lighting installation are shown on the plans by proper symbols.

Lighting symbols are shown on Standard Plan 901.85. Widths of pavement, shoulders and traffic islands are shown. The beginning and end of pavement transitions and traffic islands are shown with stationing.

901.10.3 Cable and Conduit

The actual proposed location of rigid conduit or cable-conduit is approximated on the plans. Straight-line schematic diagrams are not acceptable. Quantities of cable or cable-conduit can be taken off by scaling. Cable-conduit is normally used for underground circuits not under pavement or shoulders or in concrete barrier or structures. Where the cable-conduit is located under paved areas and shoulders (including all shoulder types) it is encased in rigid conduit. Where the entire system or circuit is in rigid conduit, cable-conduit is not used. In this case, two single conductor cables plus a bare neutral (ground) of the required size are used for each circuit. Possible combinations of cables in cable-conduit are shown in Table 901.10.3.1.

Table 901.10.3.1 Maximum* No. Cables Available in Cable-Conduit

Cable-Conduit Size Wire Sizes (AWG)
#2 #4 #6 #8
1" 2344
1-1/2"4- - -
*No more than four factory-installed conductors are available in one conduit. One bare neutral wire in addition to the insulated conductors may be used.

Where cable-conduit enters concrete barriers or structures, it enters a rigid conduit system. To minimize splices, cable-conduit is provided to the first light pole or junction box with a splice. Although the outer sheath of the cable-conduit is cut away from the cables where they enter the rigid conduit, cable-conduit is paid for to the first pole or junction box.

Conduit under pavement and shoulders for encasement of cable-conduit are sized according to Table 903.10.3.2. Each end of a rigid conduit pavement crossing is terminated in a pull box or light pole.

Table 901.10.3.2 Minimum Straight Run Conduit Sizes for Encasement of Cable-Conduit Under Pavement and Shoulders

No. of Cable-Conduits Cable-Conduit Sizes
1" 1-1/4" 1-1/2"
1 2"2"3"

Rigid conduit for lighting is used in 2, 3, 4 and 5 in. sizes. Use Table 901.10.3.3 as a guideline for minimum sizes of rigid conduit.

Table 901.10.3.3 Minimum Rigid Conduit Sizes

In trench not under pavement 2
Power supply to control station2
On structures, in median islands or median barriers 2
Under pavement or shoulders 3
In concrete bases3
Field wiring between control station and first pull box4
Pushed 4

Rigid conduit is to be of sufficient size for the amount of cable they carry. Table 901.10.3.4 shows rigid conduit sizes based on wire size and quantity.

Table 901.10.3.4 Maximum No. 600 Volt 1/C Cables in Rigid Conduit

Wire Size (AWG) Rigid Conduit Size
2" 3" 4" 5"
8 16356094
*#10 AWG not used underground.

Additional information on conduit sizing is found in EPG 902.15.5 Conduit System.

The district furnishes design data to Bridge for conduit, junction boxes and poles required on bridges.

901.10.4 Summary of Quantities and Estimate and 2B Sheets

All items of work for lighting are tabulated on the 2B sheets, either for lighting as a separate project or with roadway quantities.

901.10.5 Computation of Quantities

The computations of quantities and increments for measurement are in accordance with the specifications and the tabulation of bid items in 237.2, Title Sheet. The following rules apply to the items listed:

The cable quantities are calculated by the center-to-center distance for the following:

  • Control Station to Lighting Pole
  • Lighting Pole to Lighting Pole
  • Lighting Pole to Pull Box.

Rigid Conduit (In Trench) includes trenching and backfilling.

Additional cable quantities are added to provide slack and additional cable for future use. The additional length of each conductor cable and neutral wire, or of cable-conduit is computed as follows:

  • On Power Supply = 8 ft. per circuit.
  • In Control Station = 8 ft. per circuit.

Control Station to Lighting Pole, Lighting Pole to Lighting Pole or to Pull Box = 5% of the center-to-center distance for snaking.

  • In lighting pole = 5 ft. for each connection.
  • In pull box = 6 ft. per run.

A #10 AWG (6 mm2) single-conductor pole and bracket cable is computed as 2 x (mounting height + length of bracket arm).

The total plan quantity only, for each item, is shown on the 2B sheets to the nearest 10 ft.

901.10.6 Control Stations and Power Supplies

Written approval of the locations and details of equipment, including the cost to hookup, is obtained from the utility company furnishing power. Approved special drawings are required if standard plans cannot be used. Control stations on highway right of way are to be state owned, rather than owned by the utility company.

Power supply assemblies are located about 2 to 4 ft. inside the right of way line unless the utility pole providing service is located on the right of way. In that case, the power supply assembly is to be located as close as possible to the utility pole. If required, the base-mounted control station can be remotely located from the power supply. The control station is to be as close as possible to the lighting system and at a location that is easily accessible to Maintenance Division personnel. Clear zone requirements are also to be used in determining control station location.

A rigid conduit run is installed from the power supply to the control station. Three single conductor power cables are required for the control station. The minimum size wire is #2 AWG (35 mm2). Larger cables may be required due to voltage drop. EPG 901.12.1 Voltage Drop and Wire Sizes contains formulas for computing wire size and voltage drop.

In systems with base-mounted control stations, a pull box is to be installed at the lighting control station. Rigid conduit containing cables for branch circuits is installed from the control station to this pull box.

901.10.7 Coordination

Lighting plans are coordinated with the road, signal and signing plans to ensure conflicts with other construction features do not exist. The designer needs to become acquainted with features such as existing overhead and underground utilities to avoid conflicts.

901.10.8 Field Checks

Field checks of lighting plans are similar to the field checks required for other plans.

901.10.9 Coordination with Design Division

A representative of Design is available on request of the district at any time for review of plans, field checks, etc.

901.10.10 Preliminary Plans

Preliminary lighting layouts showing the location of all luminaires, tentative locations of control stations, power supplies and cable routing are reviewed at the district level. After approval of the preliminary layout, the district furnishes design data to Bridge Division if conduit or poles are required on structures.

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