Underground Raceway Analysis

Ductbank Route

Build conduit layouts, assign cables, and run NEC fill plus thermal checks from one workspace.

1. Validate 2. Fill 3. Thermal 4. Export
Method & Assumptions

Screening limitation: ampacity and temperature outputs use a calibrated steady-state estimator with generic thermal properties. They do not establish NEC/IEEE compliance. Final design requires actual cable construction, installation geometry, soil/backfill data, mutual heating, and an accepted ampacity method or manufacturer study.

Thermal resistance is evaluated as R = ln(D_e/D_i)/(2πk).

Variables:

  • D_e – external diameter
  • D_i – internal diameter
  • k – thermal resistivity

Background reference: calibrated ampacity estimator and IEEE 835 benchmarks

Applicability: homogeneous soil and steady-state current.

See also: Load Calculation Formulas, Cable Fill Rules, Routing Assumptions.

0 Conduits
0 Cables
0 Assigned
0 Unassigned
0 Warnings
0 Thermal Alerts
0 Ampacity Alerts

Ductbank Setup

Set the route tag, length, burial depth, and encasement assumptions used by the drawing, thermal checks, and material takeoff.

Plan / Profile

Station-Based Route Alignment

Define horizontal coordinates, finished grade, cover, and route structures. Developed profile length replaces the single route-length value in the BOM when at least two valid stations are present.

Developed length0 ft
Cover range—
Direction changes0
Structures0
IDStation (ft)Easting (ft)Northing (ft)Grade Elev. (ft)Cover (in)Action

Route Structures and Crossings

IDTypeStation (ft)Note / CrossingAction
Route model limitationsPlanning geometry only

    Ductbank Conduits

    Define each conduit and let the layout controls position the bank consistently.

    0 conduits
    ID Type Trade Size X Y Dup Del

    Cables

    Assign each cable to a ductbank conduit and provide the fields needed for fill and ampacity checks.

    No cables
    Thermal Parameters Soil, spacing, and solver assumptions
    Typical Soil Properties
    Soil TypeThermal Resistivity (°C·cm/W)
    ConditionMoisture Content (%)
    Dry2–5
    Damp5–10
    Moist10–20
    Wet / Saturated20+

    Drawing & Analysis

    Review conduit fill, cable placement, thermal overlays, and screening-level ampacity estimates.

    Ampacity Estimates

    Material Takeoff

    Ductbank Bill of Materials

    Screening quantities generated from the route length, conduit layout, civil envelope, and the selected project options below. Cable remains on the cable schedule.

    Route0 ft
    Conduit0 LF
    Concrete0 CY
    Excavation0 CY
    IncludeCategoryItemSpecification / InputsQuantityUnitBasis

    Excavation safety: Shoring is only one protective-system option. Applicability and system selection must be determined for actual site conditions by a competent person. See OSHA 29 CFR 1926.652.

    Takeoff assumptionsAdjust allowances before procurement review.
    Scope notes