Reference boundary

Preliminary run-length arithmetic only. The 3 percent threshold is a selected planning input, not a code limit or conductor approval.

Reference table

Estimate one-way aluminum conductor run length for selected currents at a 3 percent voltage-drop planning threshold.

Formula basis: one-way metres = allowed voltage drop x area / (circuit multiplier x resistivity x current); product suitability still depends on markings and local acceptance.
Conductor sizeArea (mm2)120 V 1-phase, 20 A (m)240 V 1-phase, 40 A (m)600 V 3-phase, 100 A (m)Basis
6 AWG13.342.442.448.9aluminum, 20 C resistivity, 3 percent drop
4 AWG21.267.567.577.9aluminum, 20 C resistivity, 3 percent drop
3 AWG26.7858598.2aluminum, 20 C resistivity, 3 percent drop
2 AWG33.6107107123.5aluminum, 20 C resistivity, 3 percent drop
1 AWG42.4135135155.9aluminum, 20 C resistivity, 3 percent drop
1/0 AWG53.5170.4170.4196.7aluminum, 20 C resistivity, 3 percent drop
2/0 AWG67.4214.6214.6247.8aluminum, 20 C resistivity, 3 percent drop
3/0 AWG85270.7270.7312.5aluminum, 20 C resistivity, 3 percent drop
4/0 AWG107.2341.4341.4394.2aluminum, 20 C resistivity, 3 percent drop
250 kcmil126.7403.4403.4465.9aluminum, 20 C resistivity, 3 percent drop
350 kcmil177.3564.6564.6651.9aluminum, 20 C resistivity, 3 percent drop
500 kcmil253.4806.9806.9931.7aluminum, 20 C resistivity, 3 percent drop
Use notes
  • Use this table for preliminary reference and arithmetic checks only.
  • Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.