Table
Copper Wire Maximum Run Length at 3% Drop
Copper Wire Maximum Run Length at 3% Drop reference with assumptions and boundary notes.
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 copper conductor run length for selected currents at a 3 percent voltage-drop planning threshold.
| Conductor size | Area (mm2) | 120 V 1-phase, 20 A (m) | 240 V 1-phase, 40 A (m) | 600 V 3-phase, 100 A (m) | Basis |
|---|---|---|---|---|---|
| 14 AWG | 2.08 | 10.9 | 10.9 | 12.5 | copper, 20 C resistivity, 3 percent drop |
| 12 AWG | 3.31 | 17.3 | 17.3 | 20 | copper, 20 C resistivity, 3 percent drop |
| 10 AWG | 5.26 | 27.5 | 27.5 | 31.7 | copper, 20 C resistivity, 3 percent drop |
| 8 AWG | 8.37 | 43.7 | 43.7 | 50.5 | copper, 20 C resistivity, 3 percent drop |
| 6 AWG | 13.3 | 69.4 | 69.4 | 80.2 | copper, 20 C resistivity, 3 percent drop |
| 4 AWG | 21.2 | 110.7 | 110.7 | 127.8 | copper, 20 C resistivity, 3 percent drop |
| 3 AWG | 26.7 | 139.4 | 139.4 | 160.9 | copper, 20 C resistivity, 3 percent drop |
| 2 AWG | 33.6 | 175.4 | 175.4 | 202.5 | copper, 20 C resistivity, 3 percent drop |
| 1 AWG | 42.4 | 221.3 | 221.3 | 255.6 | copper, 20 C resistivity, 3 percent drop |
| 1/0 AWG | 53.5 | 279.3 | 279.3 | 322.5 | copper, 20 C resistivity, 3 percent drop |
| 2/0 AWG | 67.4 | 351.8 | 351.8 | 406.3 | copper, 20 C resistivity, 3 percent drop |
| 3/0 AWG | 85 | 443.7 | 443.7 | 512.4 | copper, 20 C resistivity, 3 percent drop |
| 4/0 AWG | 107.2 | 559.6 | 559.6 | 646.2 | copper, 20 C resistivity, 3 percent drop |
| 250 kcmil | 126.7 | 661.4 | 661.4 | 763.7 | copper, 20 C resistivity, 3 percent drop |
| 350 kcmil | 177.3 | 925.5 | 925.5 | 1068.7 | copper, 20 C resistivity, 3 percent drop |
| 500 kcmil | 253.4 | 1322.8 | 1322.8 | 1527.4 | copper, 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.