Wire Gauge (AWG) Calculator
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A
Current vs Ampacity
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Current Draw—
Remaining Capacity—
Max Ampacity
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Load %
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Voltage Drop
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Voltage Drop %
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Wire Resistance
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Status
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AWG Ampacity Guide
14 AWG = 15 A (lighting) | 12 AWG = 20 A (outlets) | 10 AWG = 30 A (dryer) | 8 AWG = 40 A (range) | 6 AWG = 55 A (AC unit). These are NEC values for copper wire in conduit at 60°C.
Voltage Drop
Voltage Drop = 2 × Length × Current × Resistance per foot. The factor of 2 accounts for both the hot and neutral conductors. NEC recommends keeping voltage drop under 3% for branch circuits and under 5% total to the load.
Choosing Wire Gauge
Always size wire for the breaker protecting the circuit, not just the load. A 20 A breaker requires minimum 12 AWG wire. For long runs (50+ ft), consider going one gauge larger to reduce voltage drop.