Wire Size Calculator NEC 310.16

Determine minimum conductor size based on ampacity and verify voltage drop. Automatically upsizes if voltage drop exceeds limit.

Circuit Application

Branch circuits: 3% VD recommended per NEC 210.19(A) Informational Note No. 4

Load (Amps) Continuous load (3+ hours)

System Voltage

Phase

One-Way Distance (ft)

Conductor Type

OCPD / Breaker Size 110.14(C)

Determines circuit rating for 110.14(C) and EGC sizing per 250.122

Voltage Drop Limit

Ampacity Derating (optional)

When to derate: Ampacity must be adjusted when ambient temperature exceeds 30°C (86°F) per NEC 310.15(B).

Ambient Temperature

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For reference only. Verify all results with the current NEC and local amendments. See Terms of Use.