Power System Studies
Duct Bank Heat Studies
CYMCAP cable ampacity calculations for concrete-encased duct banks. Prevents thermally limited circuits and field-condition derates.
Overview
Cables in a concrete-encased duct bank operate at higher temperatures than free-air rated values suggest. We use CYMCAP to model the full geometry (conductor, insulation, duct, concrete envelope, soil resistivity) and calculate the steady-state and emergency ampacity of every cable in the bank, accounting for mutual heating between circuits. The result is a defensible, field-correct ampacity for each circuit that the AHJ will accept.
What's included
Scope of work
CYMCAP modeling of the proposed duct bank geometry
Conductor type, insulation, and shielding accounted for
Native soil thermal resistivity captured (or assumed per IEEE 442 if not measured)
Steady-state ampacity calculation per IEC 60287
Emergency overload ampacity for 100-hour, 24-hour, and similar excursions
PE-stamped ampacity report
Methodology
How the engagement runs
A consistent process means predictable timelines, fewer surprises, and a defensible record if anyone (AHJ, insurance, OSHA) asks how the work was done.
- 01
Geometry capture
Duct bank cross-section, burial depth, duct material and spacing, and cable arrangement modeled in CYMCAP.
- 02
Thermal property input
Native soil rho measured on-site where the bank is critical; otherwise assumed conservatively per IEEE 442.
- 03
Ampacity calculation
Steady-state and emergency ampacities computed per IEC 60287 with mutual heating from adjacent circuits.
- 04
Sensitivity check
Ampacity recalculated for higher soil rho and partial loading of adjacent circuits to bound the result.
- 05
Report
PE-stamped report with per-circuit ampacities, model assumptions, and acceptance package for the AHJ.
Stamped
100%
Every deliverable PE-stamped by a licensed engineer in the project state. Across all 24 registered states.
Response
1 day
We respond to every inquiry within one business day with a scoped proposal and a real timeline.
Veteran-owned
VOSB / SDVOSB
SAM.gov registered. UEI H6HAZKAD4LJ7 · CAGE 08E02. Set-aside eligible.
When you need it
Triggers
- →New duct bank construction
- →Data center, substation, or large commercial campus feeder design
- →Cable replacement where NEC table ampacity is too restrictive
- →AHJ requesting engineered ampacity in lieu of NEC tables
What you receive
Deliverables
- PE-stamped CYMCAP ampacity report
- Per-circuit ampacity tables (steady-state and emergency)
- CYMCAP model file (on request)
- Soil thermal resistivity measurement results if measured on-site
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Ready to scope your duct bank heat studies engagement?
Send us the basics (facility type, equipment, timeline) and we’ll respond with a scoped proposal within one business day.