120V Voltage Drop Calculator

Professional calculator for 120 volt AC residential circuits. Perfect for home wiring, outlets, and lighting circuits.

120V AC Calculator

Need Three-Phase or Advanced Features?

Open Full Calculator

120V Residential Wiring Guide

Standard Outlets

Most 120V outlets in homes are wired with 14 AWG for 15A circuits or 12 AWG for 20A circuits.

  • • 15A circuit: 14 AWG minimum
  • • 20A circuit: 12 AWG minimum
  • • Kitchen/bathroom: Usually 20A

Lighting Circuits

Lighting circuits typically use 15A breakers with 14 AWG wire. Long runs may need larger wire.

  • • LED lighting: Low current draw
  • • Recessed lights: Check total load
  • • Outdoor: Consider voltage drop

NEC Wire Size Requirements

Circuit Breaker Min Wire Size Common Use
15 Amp 14 AWG General outlets, lighting
20 Amp 12 AWG Kitchen, bathroom, garage
30 Amp 10 AWG Window AC, large appliances

Important Safety Notes

  • • Always follow local electrical codes
  • • Turn off power before working on circuits
  • • Have work inspected by qualified electrician
  • • NEC recommends max 3% drop for branch circuits

Related Calculators

240V Calculator

For dryers, ranges, HVAC

AC Calculator

All AC voltage calculations

Wire Size Calculator

Find the right wire gauge