Wire & Conduit Tools

Wire Size Finder — enter load and run length; we'll recommend a conductor and auto-select it below

Recommends the smallest conductor that meets NEC Table 310.16 ampacity with NEC 240.4(D) small-conductor overcurrent limits, then bumps up if needed to stay under the 3% branch-circuit voltage drop guidance in NEC 210.19(A) Informational Note. Manually clicking a different chip below clears these inputs and overrides the recommendation.

Load (Amps)

Run length (ft)

Supply voltage

Phase

1Φ 3Φ

Material

Cu Al

Conductor Selector — pick a wire size to populate all readouts and calculators below

Use ← / → arrow keys to step through sizes after clicking a chip.

Conversions

Area

mm²

↔

kcmil

↔

cmil

Temperature

°C

↔

°F

1 kcmil = 0.5067 mm² · type any value to see the inverse update live.

Readout for 14 AWG

Voltage Drop Calculator — for the selected conductor size 14 AWG

Computes actual volts dropped over your run. Closed-form: V_drop = (table value) × Amps × Length / 100. Copper conductors, 75°C, 0.8 power factor. Color thresholds reflect NEC informational note 210.19(A): <3% branch / <5% combined.

Load (Amps)

One-way length (ft)

Supply voltage

Phase

1Φ 3Φ

Cable Pulling Tension — for the selected conductor size 14 AWG

Per IEEE 1185 / IEEE 525. T_m = K · n · CMA with K = 0.008 for copper, 0.006 for aluminum; derated ×0.8 when pulling more than 3 conductors together. L_m = T_m / (W·f). Hard cap of 6,500 lbs per common cable-grip rating.

Conductor material

Cu Al

Conductors in pull

Coefficient of friction

ⓘ Bend radius (NEC 300-34): nonshielded cable ≥8× cable O.D.; shielded cable ≥12× cable O.D. Sidewall pressure at bends often limits the pull before this max tension does. Typical friction: PVC dry ~0.5, PVC w/ lube ~0.2, steel dry ~0.5, steel w/ lube ~0.3.

* Per NEC 240.4(D), overcurrent protection of small conductors is limited regardless of ampacity: 14 AWG Cu → 15 A, 12 AWG Cu → 20 A, 10 AWG Cu → 30 A (12 AWG Al → 15 A, 10 AWG Al → 25 A).

Ampacity values from 2023 NEC Table 310.16, based on 30°C ambient and not more than three current-carrying conductors in a raceway. Conduit sizes assume a 3-conductor install; for other fill conditions consult NEC Chapter 9, Tables 4 & 5.

Copper weights are bare ASTM B8 concentric-lay-stranded conductors. Aluminum weights are bare ASTM B231 (AAC 1350) concentric-lay-stranded; smaller sizes (8 AWG and below) are not standardly tabulated as AAC and are shown as —.

Voltage-drop values are volts per amp per 100 ft of copper run at 0.8 power factor; the 1Φ value already accounts for round-trip distance.

Single-Phase Transformer — Rated Line Amperes

Line current draw for a single-phase transformer at the listed kVA and secondary voltage. Useful for sizing primary protection and feeder conductors.

Single-Phase Line Current = (kVA × 1000) ÷ V_line

Three-Phase Transformer — Rated Line Amperes

Line current draw for a three-phase transformer at the listed kVA and secondary line-to-line voltage. Same table as in the Motor Circuit Selector tool.

3-Phase Line Current = (kVA × 1000) ÷ (V_line × √3)

Need a hand?

Our technical team can confirm this selection for your job

(708) 756-5600

Or stop by 103 N. Halsted St., Chicago Heights, IL