Quick answer: wire size for a 200 amp breaker
Minimum conductor for 200 A with not more than three current-carrying conductors at 30 °C (86 °F) ambient.
| Wire and terminal rating | Minimum size | Table ampacity |
|---|---|---|
| Copper, 75 °C column (THHN/THWN-2, 75 °C terminals) | 3/0 AWG | 200 A |
| Aluminum, 75 °C column (XHHW-2, SER, 75 °C terminals) | 250 kcmil | 205 A |
| Copper, 60 °C column (equipment marked 60 °C only) | 250 kcmil | 215 A |
| Aluminum, 60 °C column (equipment marked 60 °C only) | 350 kcmil | 210 A |
For circuits over 100 A, NEC 110.14(C)(1)(b) lets you use the 75 °C column unless the equipment is marked otherwise, so the 75 °C answer is the normal one. The 90 °C column (225 A for 3/0 copper, 230 A for 250 kcmil aluminum) is a starting point for derating only and cannot be used at the terminals.
200 amp service vs 200 amp subpanel
| Installation | Copper | Aluminum | Rule |
|---|---|---|---|
| Dwelling service or main feeder, 120/240 V, carrying the whole house load | 2/0 AWG | 4/0 AWG | NEC 310.12: 83% of 200 A = 166 A |
| Subpanel feeder, detached garage or shop, commercial or three-phase service | 3/0 AWG | 250 kcmil | Table 310.16, 75 °C, full 200 A |
| Four to six current-carrying conductors in one raceway | 4/0 AWG | 300 kcmil | 310.15(C)(1) 80% from 90 °C: 208 A and 208 A |
The 83% rule only applies to a single-phase dwelling service, or the feeder that carries the entire dwelling load. A 200 A subpanel fed from a 400 A service (for example, one side of a 320/400 A meter base), a shop panel, or any three-phase service needs the full 3/0 copper or 250 kcmil aluminum. A feeder to a subpanel also needs four wires, because NEC 250.24(A)(5) and 250.142(B) keep the neutral and ground separate after the service disconnect.
Wire size for 200 amps by distance (240 V)
Smallest size that keeps a 120/240 V single-phase run at or under a 3% voltage drop. The 160 A columns are the continuous-load limit of a 200 A breaker and a realistic design load for many subpanels. Ampacity sets the floor, so the table never goes below 3/0 copper or 250 kcmil aluminum.
| Run | Cu, 200 A | Cu, 160 A | Al, 200 A | Al, 160 A |
|---|---|---|---|---|
| 50 ft | 3/0 AWG | 3/0 AWG | 250 kcmil | 250 kcmil |
| 100 ft | 3/0 AWG | 3/0 AWG | 250 kcmil | 250 kcmil |
| 150 ft | 3/0 AWG | 3/0 AWG | 250 kcmil | 250 kcmil |
| 200 ft | 3/0 AWG | 3/0 AWG | 250 kcmil | 250 kcmil |
| 250 ft | 4/0 AWG | 3/0 AWG | 300 kcmil | 250 kcmil |
| 300 ft | 250 kcmil | 4/0 AWG | 400 kcmil | 300 kcmil |
| 400 ft | 300 kcmil | 250 kcmil | 500 kcmil | 400 kcmil |
| 500 ft | 400 kcmil | 300 kcmil | 600 kcmil | 500 kcmil |
Example: a 200 A subpanel in an outbuilding 300 ft from the service, with an expected load of 160 A at 240 V. 3/0 copper reaches only 293 ft at 160 A, so the run needs 4/0 AWG copper, which reaches 370 ft. In aluminum, 250 kcmil reaches 265 ft, so the answer is 300 kcmil aluminum (318 ft). Because the hots were upsized, the ground grows too (see ground).
Maximum length at 200 amps by wire size
The longest one-way run, in feet, before each size reaches the drop shown. Three-phase columns use the √3 formula. These are DC resistance figures; for large conductors in steel conduit at a low power factor, reactance adds a little more drop.
Copper
| Size | 240 V, 3% | 240 V at 160 A, 3% | 240 V, 5% | 208 V 3-ph, 3% | 480 V 3-ph, 3% |
|---|---|---|---|---|---|
| 3/0 AWG | 234 | 293 | 391 | 235 | 542 |
| 4/0 AWG | 296 | 370 | 493 | 296 | 683 |
| 250 kcmil | 349 | 436 | 582 | 349 | 807 |
| 300 kcmil | 419 | 524 | 699 | 419 | 968 |
| 350 kcmil | 490 | 613 | 817 | 490 | 1132 |
| 400 kcmil | 560 | 700 | 934 | 561 | 1294 |
| 500 kcmil | 697 | 872 | 1162 | 698 | 1611 |
| 600 kcmil | 841 | 1051 | 1401 | 841 | 1942 |
Aluminum
| Size | 240 V, 3% | 240 V at 160 A, 3% | 240 V, 5% | 208 V 3-ph, 3% | 480 V 3-ph, 3% |
|---|---|---|---|---|---|
| 4/0 AWG * | 179 | 224 | 300 | 180 | 415 |
| 250 kcmil | 212 | 265 | 354 | 212 | 490 |
| 300 kcmil | 254 | 318 | 424 | 254 | 587 |
| 350 kcmil | 297 | 371 | 495 | 297 | 687 |
| 400 kcmil | 340 | 425 | 567 | 340 | 785 |
| 500 kcmil | 424 | 530 | 707 | 424 | 980 |
| 600 kcmil | 509 | 637 | 849 | 510 | 1177 |
* 4/0 aluminum is 180 A at 75 °C. It is shown for 120/240 V dwelling services under 310.12; it is not a full 200 A feeder conductor. NEC 215.2(A)(1) Informational Note 2 recommends 3% on a feeder and 5% total to the farthest outlet. A 3% drop is 7.2 V at 240 V, 6.24 V at 208 V and 14.4 V at 480 V. Use the voltage drop calculator for your exact load, or the three-phase voltage drop calculator for 208 to 600 V.
Ground wire for 200 amps
- Equipment grounding conductor: 6 AWG copper or 4 AWG aluminum, from NEC Table 250.122 for a 200 A breaker.
- Upsized hots: 250.122(B) requires the ground to grow by the same ratio of circular mils. In the 300 ft example, going from 3/0 (167,800 cmil) to 4/0 AWG (211,600 cmil) is a ratio of 1.26, so the 6 AWG ground (26,240 cmil) must be at least 33,090 cmil: 4 AWG copper (41,740 cmil).
- Service grounding electrode conductor: for 2/0 or 3/0 copper, or 4/0 or 250 kcmil aluminum, service conductors, NEC Table 250.66 calls for 4 AWG copper or 2 AWG aluminum. A conductor to a ground rod never has to be larger than 6 AWG copper (250.66(A)), and one to a concrete-encased electrode never larger than 4 AWG copper (250.66(B)).
Conduit size for 200 amp wire
Smallest conduit at 40% fill (NEC Chapter 9 Table 1) using THHN/THWN-2 areas from Chapter 9 Table 5. "Three wires" is two hots and a neutral; "four wires" adds a third phase or a second neutral. Service rows include a ground-size wire for comparison.
| Run | Conductors | Area, in² | EMT | PVC 40 | EMT, 4 wires |
|---|---|---|---|---|---|
| Feeder, copper 75 °C | 3 × 3/0 AWG + 6 AWG | 0.854 | 2 | 2 | 2 |
| Feeder, aluminum 75 °C | 3 × 250 kcmil + 4 AWG | 1.273 | 2 | 2 | 2-1/2 |
| Dwelling service (310.12), copper | 3 × 2/0 AWG + 6 AWG | 0.718 | 1-1/2 | 1-1/2 | 2 |
| Dwelling service (310.12), aluminum | 3 × 4/0 AWG + 4 AWG | 1.053 | 2 | 2 | 2-1/2 |
| Upsized for distance (300 ft example), copper | 3 × 4/0 AWG + 4 AWG | 1.053 | 2 | 2 | 2-1/2 |
XHHW-2 aluminum has slightly different areas than THHN, so check the conduit fill calculator for your insulation. Long or bendy runs pull easier one trade size up.
How much load can a 200 amp circuit carry?
| System | At 200 A | Continuous (160 A) |
|---|---|---|
| 120/240 V single phase (240 V load) | 48.0 kW | 38.4 kW |
| 208 V three phase | 72.1 kW | 57.6 kW |
| 240 V three phase | 83.1 kW | 66.5 kW |
| 480 V three phase | 166.3 kW | 133.0 kW |
| 600 V three phase | 207.8 kW | 166.3 kW |
Loads that run three hours or more must be sized at 125% under NEC 210.19(A) and 215.2(A)(1), which limits a 200 A breaker to 160 A of continuous load. Figures assume a balanced load and unity power factor. The amps to watts calculator handles power factor, and the kVA calculator covers transformers and services.
When more than three wires share a conduit
With four to six current-carrying conductors in one raceway, NEC 310.15(C)(1) cuts ampacity to 80%. Starting from the 90 °C column, 3/0 copper drops to 180 A and 4/0 copper to 208 A, so a 200 A circuit in a shared conduit needs 4/0 copper. In aluminum, 250 kcmil drops to 184 A and 300 kcmil to 208 A. Hot rooftops add an ambient correction too; see wire derating.
In Canada
CEC Table 2 (copper) and Table 4 (aluminum) give the same 75 °C ampacities for these sizes, so 3/0 copper (200 A) or 250 kcmil aluminum (205 A) carries 200 A. Canada does not use the NEC 310.12 83% rule; single-dwelling service conductors have their own minimum sizes in CEC Table 39, so check the CEC before sizing a Canadian service. Rule 8-102 makes the 3% and 5% voltage drop limits mandatory, and the Canadian voltage drop tables give 200 A feeder lengths in metres. Use the Canadian wire size calculator for your run.
For smaller feeders, see wire size for 100 amps.
This page is a quick reference. Confirm against the code edition your jurisdiction has adopted, the equipment markings and your inspector.