Code reference · NEC Table 310.16; 110.14(C); 210.20(A); 210.19(A) IN
What size wire for a 175 amp breaker?
For a 175 A breaker, the minimum copper conductor is 2/0 AWG (175 A at the 75°C column of Table 310.16, which is what standard breaker terminations allow per 110.14(C)). In aluminum, the minimum is 4/0 AWG (180 A at 75°C).
That answer assumes ≤3 current-carrying conductors, 30°C ambient, and a load that isn't continuous. A continuous load (3+ hours — EV charging, water heaters, most lighting) must be limited to 80% of the device: 140 A on this circuit (NEC 210.20(A)). Hot locations or bundled raceways derate the conductor further (310.15) and can push you up a size.
Distance is the other size driver. At 140 A load and 100 ft one-way on 2/0 AWG copper at 240 V, the computed voltage drop is 2.71 V (1.13%) — inside the NEC's recommended 3% (210.19(A) Informational Note).
Run the numbers yourself
Need this as a permit-ready document?
One Document Credit ($29) buys a full clause-cited compliance PDF — wire sizing, voltage drop, overcurrent protection, every value traceable to the section it came from.
Get your document →Every numeric value on this page is computed by the CircuitProof calculation engine — the same golden-tested code that renders our permit documents — not typed by hand. Code text is paraphrased and cited; always verify against your jurisdiction's adopted edition and a licensed professional before installation. Design documentation, not a stamped drawing.
More references: What size wire for a 15 amp breaker? · What size wire for a 20 amp breaker? · What size wire for a 30 amp breaker? · What size wire for a 40 amp breaker? · What size wire for a 50 amp breaker? · What size wire for a 60 amp breaker? · all 97 references