CEC 2024 Canadian Cable Sizing

Reference aid, not the Code. This calculator supports engineering checks but does not replace CSA C22.1:24, inspection requirements, professional judgement, or the rules in force at the installation site. It uses the national CEC baseline and excludes provincial and territorial amendments.

Scope

The calculator automatically sizes balanced, 60 Hz, low-voltage three-phase general loads and one three-phase motor. Parallel runs are identical in material, size, insulation, length, and termination conditions. The search tries database conductor rows in order for one run, then two runs, up to six, so the result always prefers the fewest runs.

Four checks at once

A conductor is correctly sized only when a single size satisfies every governing criterion: it carries the derated design current (Rule 4-004), respects the termination temperature rating (Rule 4-006), keeps voltage drop within 3% for the circuit and 5% in total (Rule 8-102), and coordinates with its overcurrent device (Rule 14-104). The controlling size is the largest that any one check demands, never the first that passes.

General-load inputs

Real power in kW, apparent power in kVA, or a design current in amperes from the equipment nameplate or load schedule; line voltage and power factor.
Continuous-load selection and 80%- or 100%-rated equipment (Rule 8-104: 125% conductor uplift).
Three-phase current is calculated from I = P/(√3 V PF) or I = S/(√3 V).

Motor inputs

Horsepower and voltage select full-load current from CEC Table 44. That FLC—not calculated horsepower current or nameplate current—is used for the 125% branch-conductor requirement and Table 29 branch protection. Nameplate current is used separately for the selected running-overload basis.

Motor feeders

A feeder supplying several motors lists each motor's horsepower and quantity. Conductor demand follows Rule 28-108: 125% of the largest motor's Table 44 FLC plus the FLC of every other motor. Feeder protection follows Rule 28-204: the largest motor's Table 29 branch rating plus the other motors' FLC, rounded to the next Table 13 standard rating. Each motor's own branch circuit and running overload must still be sized separately.

Installation and checks

Copper or aluminium, 60/75/90°C insulation, and termination-temperature cap.
Raceway/cable (Tables 2 or 4) or free-air (Tables 1 or 3) installation.
Table 5A ambient and Table 5C grouping correction. Separate raceways contain three phase conductors; a common raceway contains 3 × runs. When the neutral carries harmonic or unbalanced current it is counted as current-carrying and the count becomes four per run.
Three-phase voltage drop V_d = √3 I L (R cos φ + X sin φ) from authoritative R/X data with equal current sharing, a 3% or 5% circuit limit, and a 5% total limit that includes any upstream drop you enter. The report also states the longest run that would still pass at this current.
Table 13 OCPD ratings, small-conductor and parallel-conductor rules, and Table 16 bonding conductors.

Checking a nominated conductor

Optionally nominate a size and number of parallel runs. The calculator evaluates that conductor against every check and reports its ampacity margin, loading, and voltage-drop headroom alongside the automatic recommendation. A size absent from the selected table columns is reported as not in table.

Separate routing provides one complete three-phase set and one bonding conductor per raceway. Common routing uses one enclosure and one bonding conductor, while grouping applies to every phase conductor together.

Reading the result

A passing result includes conductor size and run count, load/design currents, corrected ampacity, voltage drop, OCPD, motor overload where applicable, bonding size/quantity, governing criterion, warnings, the full candidate trace, and lookup provenance. If every combination through six runs fails, the result is NO_COMPLIANT_SIZE and lists the failed checks; it never substitutes the largest conductor.

Worked Examples

The 2 examples below are the validation cases for this calculation. Each one was produced by the calculation engine from the inputs shown, every figure was checked against the independent reference quoted at the end of the example, and the same cases are run against every engine build (see validation scorecard, tool fe_calc_cable_size; worked examples for every calculation).

#	Case	Conductor	I_design (A)	I_z (A)	V_d (%)	OCPD (A)	Result
1	100 kW continuous load at 600 V, 50 m, CEC auto-sized to 1/0 AWG	1 × 1/0 Cu	133.6	150.0	0.66	150	PASS
2	50 hp motor at 600 V: Table 44 FLC sizes the branch conductor	1 × 6 Cu	65.0	65.0	1.16	150	PASS

Example 1 — 100 kW continuous load at 600 V, 50 m, CEC auto-sized to 1/0 AWG

Rule 8-104 125 % demand (133.6 A) against the Table 2 ampacity capped at the 75 °C termination column; 150 A OCPD from Table 13 and a Table 16 bonding conductor.

Given: 100 kW at 600 V, PF 0.9 (default), continuous load on 80 percent equipment; copper conductors, 90 °C insulation, 75 °C terminations, raceway or cable, ambient 30 °C, parallel sets in separate raceways, copper bonding; route 50 m; voltage-drop limit 3 % (default). CSA C22.1:24 tables.

Load current	I = 100 kW × 1000 / (√3 × 600 × 0.9) = 106.92 A; I_design = 1.25 × 106.92 = 133.65 A (Rule 8-104: continuous load on 80 %-rated equipment)
Overcurrent device	Target = I_design 133.65 A → next Table 13 standard rating 150 A
Candidates tried	Fewest runs first, table order: 1 × 14 (fails ampacity, VD, total VD, OCPD, small conductor), 1 × 12 (fails ampacity, VD, total VD, OCPD, small conductor), 1 × 10 (fails ampacity, VD, total VD, OCPD, small conductor), 1 × 8 (fails ampacity, VD, OCPD), 1 × 6 (fails ampacity, OCPD), 1 × 4 (fails ampacity, OCPD), 1 × 3 (fails ampacity, OCPD), 1 × 2 (fails ampacity, OCPD), 1 × 1 (fails ampacity, OCPD), 1 × 1/0 (passes).
Check — ampacity	Table 2, 1/0 AWG/kcmil: 170 A (90 °C column) × 1 (Table 5A, 30 °C) × 1 (Table 5C, 3 conductors) = 170.0 A; termination cap (75 °C column) 150 A → 150.0 A per conductor × 1 run = 150.0 A vs I_design 133.65 A PASS
Check — voltage drop	R = 0.4379 Ω/km, X = 0.0749 Ω/km (AS/NZS 3008 proxy data); V_d = √3 × 106.92 × 0.050 × (0.4379 × 0.9 + 0.0749 × 0.4359) = 3.95 V = 0.659 % of 600 V, limit 3 % PASS; total with 0 % upstream = 0.659 % vs 5 % PASS
Check — overcurrent coordination	OCPD 150 A ≤ conductor ampacity 150.0 A (or the next standard size rule, Rule 14-104) PASS; small-conductor OCPD limit PASS; parallel minimum size PASS
Bonding conductor	Table 16 for a 150 A device: 6 AWG/kcmil Cu × 1
Result	5/5 checks pass → PASS; 1 × 1/0 AWG/kcmil with 150 A OCPD; governing: current carrying capacity. The termination-temperature ampacity cap governs the selected conductor. Voltage-drop impedance uses a cross-standard AS/NZS 3008:2017 proxy; confirm suitability for the actual Canadian cable construction and arrangement. Some CEC rule data used are user-accepted estimates pending verification against the licensed code; treat the result as provisional.
Reference	Hand calculation: I = 100 kW / (√3 × 600 V × 0.9) = 106.92 A, × 1.25 (continuous load, 80 %-rated equipment) = 133.65 A; next standard OCPD 150 A (CSA C22.1:24 Table 13); with 90 °C insulation and 75 °C terminations (Table 2), 1 AWG Cu caps at its 75 °C value below 133.65 A and 1/0 AWG is the first conductor that carries the design current and coordinates with 150 A. (validation case `c0041-100kw-600v-50m`)

Example 2 — 50 hp motor at 600 V: Table 44 FLC sizes the branch conductor

Motor conductors at 125 % of the 52 A Table 44 current; the 150 A inverse-time breaker (250 %) exceeds the 65 A conductor, which Rule 28 permits because the overload relay protects the conductor.

Given: 50 hp motor at 600 V, nameplate 45 A, inverse time breaker, overload basis other; copper conductors, 90 °C insulation, 75 °C terminations, raceway or cable, ambient 30 °C, parallel sets in separate raceways, copper bonding; route 50 m; voltage-drop limit 3 % (default). CSA C22.1:24 tables.

Load current	FLC = 52.0 A (Table 44, 50 hp at 600 V); I_design = 1.25 × 52.0 = 65.00 A (Rule 28-106); running overload 45 × 1.15 = 51.75 A
Overcurrent device	Branch protection target = 52.0 × 250 % (Table 29, inverse time breaker) = 130.0 A → next Table 13 standard rating 150 A
Candidates tried	Fewest runs first, table order: 1 × 14 (fails ampacity, VD, total VD), 1 × 12 (fails ampacity, VD), 1 × 10 (fails ampacity), 1 × 8 (fails ampacity), 1 × 6 (passes).
Check — ampacity	Table 2, 6 AWG/kcmil: 75 A (90 °C column) × 1 (Table 5A, 30 °C) × 1 (Table 5C, 3 conductors) = 75.0 A; termination cap (75 °C column) 65 A → 65.0 A per conductor × 1 run = 65.0 A vs I_design 65.00 A PASS
Check — voltage drop	R = 1.681 Ω/km, X = 0.0819 Ω/km (AS/NZS 3008 proxy data); V_d = √3 × 52.00 × 0.050 × (1.681 × 0.9 + 0.0819 × 0.4359) = 6.97 V = 1.162 % of 600 V, limit 3 % PASS; total with 0 % upstream = 1.162 % vs 5 % PASS
Check — overcurrent coordination	Motor branch device 150 A may exceed the 65.0 A conductor; the overload relay (51.7 A) protects it (Rule 28-200) PASS; small-conductor OCPD limit PASS; parallel minimum size PASS
Bonding conductor	Table 16 for a 150 A device: 6 AWG/kcmil Cu × 1
Result	5/5 checks pass → PASS; 1 × 6 AWG/kcmil with 150 A OCPD; governing: current carrying capacity. The termination-temperature ampacity cap governs the selected conductor. Voltage-drop impedance uses a cross-standard AS/NZS 3008:2017 proxy; confirm suitability for the actual Canadian cable construction and arrangement. Some CEC rule data used are user-accepted estimates pending verification against the licensed code; treat the result as provisional.
Reference	Hand calculation: CSA C22.1:24 Table 44 FLC for 50 hp at 600 V = 52 A; conductors at 125 % = 65 A; smallest Cu conductor with 75 °C termination ampacity ≥ 65 A (Table 2) is 6 AWG. (validation case `c0041-motor-50hp-600v`)

Licensed data availability

No licensed CEC values are bundled with this component. If the complete 2024 dataset is unavailable or fails audit, calculation requests return a service-unavailable message and are not saved. Administrators should use the documented three-file import sequence and run python manage.py audit_cec_tables --edition 2024. This help page intentionally does not reproduce full licensed tables.