This chart provides guidelines for copper conductors (24 AWG to 12 AWG) used in low voltage applications such as 12 V and 24 V systems. The charts below help you determine the appropriate wire gauge based on the allowable voltage drop and the load current.
Note: The allowed voltage drop is assumed to be 3% of the supply voltage (0.36 V for 12 V systems and 0.72 V for 24 V systems). Calculations assume a two conductor run (supply and return) with load currents starting at 250 mA (with additional columns for 500 mA, 1 A, and 2 A).
This table lists the resistance values for copper wires in various AWG sizes. It provides both the resistance per 1,000 ft and per ft. These values are used in voltage drop calculations to determine how much voltage is lost over a given distance.
| AWG | Resistance (Ω/1000 ft) | Resistance (Ω/ft) |
|---|---|---|
| 24 | 25.67 | 0.02567 |
| 22 | 16.14 | 0.01614 |
| 20 | 10.15 | 0.01015 |
| 18 | 6.385 | 0.00639 |
| 16 | 4.016 | 0.00402 |
| 14 | 2.525 | 0.00253 |
| 12 | 1.588 | 0.00159 |
This chart shows the estimated maximum one–way run lengths for a 12 V system. The values are based on a maximum voltage drop of 0.36 V (3% of 12 V) at various load currents. Use this table to select a wire gauge that provides an adequate run length for your application.
| Gauge | Resistance (Ω/ft) | Max Run @ 250 mA (ft) | Max Run @ 500 mA (ft) | Max Run @ 1 A (ft) | Max Run @ 2 A (ft) |
|---|---|---|---|---|---|
| 24 AWG | 0.02567 | ~28 ft | ~14 ft | ~7 ft | ~3.5 ft |
| 22 AWG | 0.01614 | ~45 ft | ~22 ft | ~11 ft | ~5.6 ft |
| 20 AWG | 0.01015 | ~71 ft | ~36 ft | ~18 ft | ~9 ft |
| 18 AWG | 0.00639 | ~113 ft | ~56 ft | ~28 ft | ~14 ft |
| 16 AWG | 0.00402 | ~179 ft | ~90 ft | ~45 ft | ~22.4 ft |
| 14 AWG | 0.00253 | ~284 ft | ~142 ft | ~71 ft | ~35.6 ft |
| 12 AWG | 0.00159 | ~453 ft | ~226 ft | ~113 ft | ~56.6 ft |
This chart displays the estimated maximum one–way run lengths for a 24 V system. The values are based on a maximum voltage drop of 0.72 V (3% of 24 V) at the various load currents. Compare these values with your installation requirements to choose the appropriate wire gauge.
| Gauge | Resistance (Ω/ft) | Max Run @ 250 mA (ft) | Max Run @ 500 mA (ft) | Max Run @ 1 A (ft) | Max Run @ 2 A (ft) |
|---|---|---|---|---|---|
| 24 AWG | 0.02567 | ~56 ft | ~28 ft | ~14 ft | ~7 ft |
| 22 AWG | 0.01614 | ~89 ft | ~45 ft | ~22 ft | ~11.2 ft |
| 20 AWG | 0.01015 | ~142 ft | ~71 ft | ~35 ft | ~17.7 ft |
| 18 AWG | 0.00639 | ~225 ft | ~113 ft | ~56 ft | ~28.2 ft |
| 16 AWG | 0.00402 | ~358 ft | ~179 ft | ~90 ft | ~44.8 ft |
| 14 AWG | 0.00253 | ~569 ft | ~285 ft | ~142 ft | ~71.1 ft |
| 12 AWG | 0.00159 | ~906 ft | ~453 ft | ~226 ft | ~113.2 ft |
