What size wire for 150 amps at 200 feet?
Short answer: For a 150 amp load 200 feet away (one way) at 240 V, use 2/0 AWG copper or 4/0 AWG aluminum in conduit with 75 °C terminations, which keeps voltage drop at 2.4% and 2.5%. In NM-B (Romex) cable it is 3/0 AWG copper. The breaker stays 150 A; the extra size is only for distance.
150 amps at 200 feet: wire size by type
| Wire type | Size by ampacity | Size for 200 ft (≤3% drop) | Voltage drop |
|---|---|---|---|
| Copper THHN/THWN-2 in conduit, 75 °C | 1/0 AWG | 2/0 AWG | 2.42% |
| Aluminum XHHW-2 in conduit, 75 °C | 3/0 AWG | 4/0 AWG | 2.50% |
| Copper NM-B (Romex) cable, 60 °C | 3/0 AWG | 3/0 AWG | 1.92% |
| Aluminum SER / NM-B cable, 60 °C | 4/0 AWG | 4/0 AWG | 2.50% |
That is one or more sizes above the 1/0 AWG that ampacity alone allows: at 200 ft the run, not the breaker, decides the gauge. NEC 250.122(B) then requires the equipment ground to be increased in proportion: start from 6 AWG copper for a 150 A breaker.
Voltage drop of each gauge over 200 ft
| Wire | Volts lost at 150 A | Drop at 150 A | Drop at 120 A (80%) |
|---|---|---|---|
| 1/0 AWG copper | 7.32 V | 3.05% | 2.44% |
| 2/0 AWG copper | 5.80 V | 2.42% | 1.93% |
| 3/0 AWG copper | 4.60 V | 1.92% | 1.53% |
| 4/0 AWG copper | 3.65 V | 1.52% | 1.22% |
| 250 kcmil copper | 3.09 V | 1.29% | 1.03% |
voltage drop = 2 × length × resistance per 1,000 ft × amps ÷ 1,000
= 2 × 200 × R(2/0 AWG) × 150 ÷ 1,000 = 5.80 V
percent = 5.80 ÷ 240 × 100 = 2.42%
If the real load is the 80% continuous maximum (120 A, as with an EV charger on a 150 A breaker), copper in conduit can be 1/0 AWG. 3% is the NEC's recommendation for a branch circuit (Informational Note to 210.19), not a hard rule, but motors, compressors and chargers run better with it.
Same 150 A, other distances
50 ft · 75 ft · 100 ft · 150 ft. Minimum sizes with no distance correction: what size wire for a 150 amp breaker.
Other loads at 200 feet
30 A · 40 A · 50 A · 60 A · 100 A · 125 A · 200 A
Change the numbers in the calculator
Safety. A 150 A circuit or feeder over 200 ft needs a permit almost everywhere in the US. Buried runs have their own depth and conduit rules (NEC 300.5), and equipment nameplates override any general table.