Wire Sizing Console

Conductor ampacity, derating, overcurrent protection, conduit fill, and voltage drop from the NEC. Drag the handle on any number field to sweep it, or type directly.

Load & circuit

Load current

400

Drag around the dial, or type the exact amperage.

Duty cycle

System voltage

Phase

Motor

Motor horsepower

Phase

Motor voltage

Branch-circuit protection device

Nameplate FLA (optional — for overload setting)

Service factor ≥1.15 or 40°C rise?

Conductor

Material

Insulation type

Terminal temperature rating (110.14(C) cap)

Site conditions

Ambient temperature

°C

−20

NEC baseline is 30°C (86°F).

Current-carrying conductors bundled together

Parallel conductors›

Split across parallel sets (310.10(G))

Number of parallel sets per phase

Each set is sized to carry an equal share of the total load. Minimum conductor size for a parallel set is 1/0 AWG.

Voltage drop

One-way distance

500

Longer runs? Type the value directly — the dial covers common ranges.

Max allowable voltage drop

3% branch / 5% total is the common design target — informational, not a hard NEC limit.

Conduit & fill›

Conduit type

Total conductors in this raceway (incl. neutral & ground)

wires

Sizing assumes all conductors match the recommended conductor size, using THHN/THWN-2 dimensions (Table 5) as the approximation for area.

Sizing…

Minimum required ampacity

—

Recommended conductor

—

Motor circuit protection

Table full-load current (FLC)—

Min. conductor ampacity (125% FLC)—

Max branch-circuit protection—

Recommended overload setting—

Overcurrent protection

Standard breaker / fuse rating—

Equipment grounding conductor

Minimum EGC size (Table 250.122)—

Based on the rating of the overcurrent device ahead of the circuit, not the conductor ampacity.

Voltage drop

—

Conduit fill

Minimum trade size—

Fill—

Show full calculation

AWG / kcmil	Table amp.	× ambient	× bundle	Adjusted	Terminal cap	Allowable	Result