What Is the Voltage Drop for 6 AWG at 24A and 125 Feet?

6 AWG at 24A and 125 feet: 2.95V drop (2.46% on 120V), computed on the single-phase / DC basis. Every conductor has resistance, and longer runs at higher currents drop more voltage. Use this calculation to check whether your run clears the 3% branch-circuit drop target before pulling wire.

6 AWG, 24A, 125ft · single-phase / DC

2.95 V drop (2.46% on 120V)

On 120V circuit2.46%

On 240V circuit1.23%

Circuit basis: This uses the single-phase / DC round-trip formula (factor of 2) for the voltage drop across the two circuit conductors. For a three-phase line-to-line run use the three-phase version of the page (append ?type=3ph). Switch to the three-phase version →

Gauge

6 AWG

Amps

Feet

Drop @ 120V

2.95V (2.46%)

Assumes a 120V source on a single-phase / DC circuit. Use the circuit-basis link above to switch between single-phase/DC and three-phase.

Voltage Drop Formula (single-phase / DC)

V_drop = (2 × L × I × R) ÷ 1000

(2 × 125 × 24 × 0.491) ÷ 1000 = 2.95 V

DC and single-phase AC use the round-trip factor of 2. Current travels out to the load on one conductor and returns on another.

For a three-phase circuit at the same amps and distance, see the three-phase version (uses √3 instead of 2, so the drop is about 13.4% lower).

Percentage

%VD = (V_drop ÷ V_source) × 100

On 120V: (2.95 ÷ 120) × 100 = 2.46%

On 240V: (2.95 ÷ 240) × 100 = 1.23%

How This Estimate Changes with Run Length and Gauge

Gauge Check

6 AWG clears the 3% drop target at these inputs. A smaller conductor may also meet it with less margin. See the minimum gauge for this load and distance.

Impact of Distance

Voltage drop is proportional to distance. Here is 6 AWG at 24A at different distances:

Distance	Drop (V)	% on 120V	% on 240V	NEC (120V)
25ft	0.5892V	0.491%	0.2455%	OK
50ft	1.18V	0.982%	0.491%	OK
75ft	1.77V	1.47%	0.7365%	OK
100ft	2.36V	1.96%	0.982%	OK
150ft	3.54V	2.95%	1.47%	OK
200ft	4.71V	3.93%	1.96%	Caution
300ft	7.07V	5.89%	2.95%	Past 5%

Same Run, Different Wire Gauges

How does wire gauge affect voltage drop for 24A at 125 feet on 120V single-phase / DC? Only gauges whose branch-circuit OCP cap is at or above the 24A load are listed, since thinner gauges would fail the ampacity check before drop even matters.

Gauge	Drop (V)	% on 120V	% on 240V	3% Target (120V)
6 AWG	2.95V	2.46%	1.23%	OK
4 AWG	1.85V	1.54%	0.77%	OK
3 AWG	1.47V	1.23%	0.6125%	OK
2 AWG	1.16V	0.97%	0.485%	OK
1 AWG	0.924V	0.77%	0.385%	OK
1/0 AWG	0.732V	0.61%	0.305%	OK

Related Calculations

cable Wire size: 24A, 125ft bolt Watts to amps calculator functions Voltage drop formula

Frequently Asked Questions

What is the voltage drop for 6 AWG at 24A and 125ft?expand_more

6 AWG carrying 24A over 125ft has a 2.95V drop (2.46% on 120V). Reference: 1.23% on 240V.

Is voltage drop worse on 120V or 240V?expand_more

Same wire, same amps, same distance: the volts dropped are identical. But the percentage is worse on 120V because the drop is a larger fraction of the source voltage. This run would be 1.23% on 240V versus 2.46% on 120V.

What wire gauge should I use instead of 6 AWG for this run?expand_more

6 AWG already sits within the 3% branch-circuit drop target at these inputs (2.46% on 120V). Going to a larger gauge is only useful if you want more headroom for future load growth, longer runs, or tighter drop targets like the 5% feeder+branch total recommendation used in sensitive or motor-heavy installations.

Does 6 AWG meet the 3% drop target at 24A and 125ft on 120V?expand_more

On 120V, this run sits at 2.46%, which is within the 3% branch and 5% feeder+branch total drop targets. NEC 210.19(A) Informational Note 4 cites 3% for branch circuits and 5% for total feeder+branch drop as performance recommendations, not hard code requirements.

Why does distance affect voltage drop?expand_more

Voltage drop is proportional to distance. The formula multiplies by 2 × the distance (out and back). Doubling the run doubles the drop.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.