LV: NEC Table 310.16/310.17 · CEC Tables 1-4 (scoped 0-5 kV). Ampacity here is thermal - voltage doesn't change LV table values.
2Circuit
Load current (A)
System voltage (V)
One-way length (m)
Length never changes ampacity - it drives the voltage drop check. Set 0 to skip.
System
DC uses the same ampacity tables - they are thermal limits and carry no AC/DC distinction. Voltage drop switches to a DC basis (no reactance): CEC Table D3's own DC column, or NEC Ch.9 Table 8 DC resistance. Article 690 (PV), 692 (fuel cell), 480 (batteries) and CEC Section 64 rules are NOT applied.
3Conductor
Material
Parallel sets per phase (310.10(G) / 12-108: min 1/0; max 12 here)
Insulation rating (TW · RW75 · RW90/TECK90)
Termination rating (110.14(C) / 4-006)
MV cable rating (shielded)
Shielded MV cable, 100%/133% insulation level per project spec. Terminations are engineered (IEEE 48 stress cones) - the LV termination-column check doesn't apply.
Cable construction
Selects which Table 315.60(C) applies. Single conductors = separate spaced cables. Triplexed = three singles twisted into one assembly. 3-conductor cable = three conductors under one overall covering (e.g. TECK). Only single conductors isolated in air are tabulated above 35 kV.
Shield grounding
NEC Table 315.60(C) ampacities assume shields grounded at ONE point. Grounding at both ends induces circulating shield current that heats the cable and reduces ampacity (typ. 5-15%, IEEE 575). NEC provides no correction table - the tool applies a conservative estimate you must confirm with a cable-specific study.
A steel raceway raises both resistance and reactance - NEC Chapter 9 Table 9 publishes separate steel columns, and the tool uses them for the voltage-drop calculation.
Ambient temperature (°C)
MV tables are based on 40 °C air / 20 °C earth ambient.
Burial depth to top of raceway/cable (mm)
CEC Appendix D - underground ≥ 1/0 AWG (Rule 4-004)
Cable arrangement
Conductor distribution in raceways
D9: each phase conductor in its own dedicated buried raceway (Diagram D9 spacing). D11: all three phases share one raceway (bundled). Flat vs trefoil applies only to direct-buried trenches.
A concrete-encased duct bank (conduits embedded in a poured concrete envelope) uses a higher thermal resistance basis (RHO 60 °C·cm/W concrete vs. 90 °C·cm/W earth) and a shallower reference depth (760 mm to top of bank) than an individually buried conduit run - the two tables give different ampacities. Pick whichever matches the actual installation.
CEC MV cable tray exposure - Appendix D Table D17M/D17N
Table D17 footnotes: indoor ampacities assume no exposure to the sun and no wind; outdoor ampacities assume exposure to the sun (no wind). Outdoor runs roughly 8-20% lower - pick whichever matches the actual installation.
Other circuits sharing this raceway
CCC is derived automatically: phases (+ neutral if toggled) × sets in this raceway, plus the same per circuit added. Derived total appears in the calculation trace.
Table 5B applies to Tables 1 and 3 (free air) where two to four insulated single conductors run in contact rather than spaced. Verify factors against your C22.1 copy.
5Voltage drop
CEC 8-102: 3% in a feeder or branch circuit, 5% total from service to point of use (mandatory). With a length entered, VD is always reported; the toggle controls whether the conductor is upsized to meet the limit.
VD limit
Power factor (0.1-1)
Disclaimer and reference standards
Engineering aid - verify before use. Results are not a stamped design.
The engineer of record is responsible for the final selection, and no warranty is expressed
or implied.
LV ampacity: NEC 2023 Table 310.16 (raceway/cable/earth) and 310.17 (free air); CEC Tables 1-4.
The two sets have been harmonized since 2012 but remain independently published - check both if cross-referencing.
LV underground: CEC uses CSA C22.1:21 Appendix D, Tables D8A-D11B (Diagrams D8-D11).
Those are three-phase arrangements - every column is "n cables per phase" and each table's Note 1
bounds it at three current-carrying conductors - so a 2-wire single-phase run is sized on Tables 2/4
with the Table 5A/5C factors instead.
NEC uses Informative Annex B, Table B.2(10) Details 9/10 (directly buried) and Table B.2(7) Details 1-3
(duct bank). Annex B is informative; the mandatory NEC basis is Table 310.16.
MV ampacity: NEC 2023 Tables 315.60(C)(1)-(20) - the complete set covering single conductors,
triplexed assemblies, and three-conductor cable, installed in free air, in conduit in air, in underground
ducts, or directly buried. Ampacities assume shields grounded at one point. Only single conductors isolated
in air are tabulated above 35 kV.
Termination temperature: CEC Rule 4-006 / NEC 110.14(C) - the usable column is set by the
lowest-rated termination in the circuit.
Bonding / EGC: CEC Table 16; NEC Table 250.122.
Voltage drop: CEC Rule 8-102 with Appendix D Table D3 (CSA C22.1:24 - K in Ω/circuit-km, Raceway column, pf-interpolated between the published 80%/90% columns, Note 3 temperature correction, Note 2 published f factor: 1.73 for 3-phase line-to-line, 2 otherwise). NEC Chapter 9 Table 9 alternating-current resistance and reactance, with separate steel-raceway columns. Table 8 (DC) is used only where Table 9 has no row, and is labelled when it is.
Overcurrent protection: CEC Rule 14-104 with Table 13; NEC 240.4(B), 240.4(D) and 240.6(A).