Conductor Sizing (AC)

1Code & voltage class

Voltage class
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.
Phase

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)

4Installation conditions

Ambient temperature (°C)
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.

5Voltage drop

CEC 8-102: 3% max in any single feeder or branch circuit (mandatory); 5% max cumulative from service to utilization point (mandatory). The 5% limit applies to the total system, not a single circuit. With a length entered, VD is always reported; the toggle controls whether the conductor is upsized.
Power factor (0–1)
VD limit (%)
CEC / NEC Reference notes
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). 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; NEC Chapter 9 impedance data.

Overcurrent protection: CEC Rule 14-104 with Table 13; NEC 240.4(B) and 240.6(A).

Rev 1.9.7 — 2026 · By Koorosh Moghadam