What Size Wire for a 200 Amp Service?
For a single-family dwelling service, use 2/0 AWG copper or 4/0 AWG aluminum. A 200 amp feeder to a subpanel that serves only part of the load needs 3/0 copper or 250 kcmil aluminum.
The answer
Dwelling service: 2/0 AWG copper / 4/0 AWG aluminum
Subpanel or feeder: 3/0 AWG copper / 250 kcmil aluminum
| Case | Copper | Aluminum |
|---|---|---|
| Dwelling service Single-family home, 83% rule (required 166 A) | 2/0 AWG 175 A, 67.4 mm² | 4/0 AWG 180 A, 107.2 mm² |
| Subpanel / feeder Part of the load or non-dwelling (required 200 A) | 3/0 AWG 200 A, 85.0 mm² | 250 kcmil 205 A, 126.7 mm² |
On this page
How the answer is worked out
For a single-family dwelling, NEC 310.12 lets the service conductors carry 83% of the rating. 200 A × 0.83 = 166.0 A. The smallest copper size rated at least that much at 75 °C is 2/0 AWG (175 A), and the smallest aluminum size is 4/0 AWG (180 A).
A subpanel or feeder that serves only part of the load, or any non-dwelling service, takes the full rating with no 83% reduction. For 200 A at 75 °C that is 3/0 AWG copper or 250 kcmil aluminum.
This tool uses the 75 °C column for every service size. The 60 °C column is not used for service conductors here, so the sizes above are the values to compare with your utility and inspector.
The 83% rule at 200 amps
For a single-family dwelling service, NEC 310.12 allows 83% of the rating: 200 × 0.83 = 166 A. 2/0 AWG copper is rated 175 A at 75 °C and 4/0 AWG aluminum is rated 180 A, so each is large enough.
Subpanels and non-dwelling feeders
The reduction does not apply to a feeder that serves only part of the load, or to non-dwelling installations. For those, a 200 amp breaker needs conductors rated 200 A at 75 °C: 3/0 AWG copper or 250 kcmil aluminum.
Long service runs
If the meter or main is far from the house, check voltage drop as well as ampacity: a long run may need one or two sizes larger than the minimum. Use the voltage drop calculator and confirm the service requirements with your utility and inspector.
How far can you run it? (3% voltage drop)
The distance table uses the same resistance-only model as the calculator, with a 3% limit and the wire at 75 °C. Aluminum has about 1.6 times the resistance of copper for the same size, so an aluminum run of the same length drops more voltage.
Assumes the full 200 A load on a single-phase 240 V circuit, a 75 °C conductor, copper or aluminum, a 3% voltage drop limit and the one-way length in the table. Aluminum shows a dash where that size cannot carry the full current.
| Wire size | Copper | Aluminum |
|---|---|---|
| 3/0 AWG | 234.8 ft [71.6 m] | — |
| 4/0 AWG | 296.1 ft [90.2 m] | — |
| 250 kcmil | 349.8 ft [106.6 m] | 212.4 ft [64.7 m] |
| 300 kcmil | 419.7 ft [127.9 m] | 254.9 ft [77.7 m] |
Before you buy wire
The table is a starting point. Work through this list before you order conductors, and keep the answer that matches your real installation.
- Read the equipment nameplate and the breaker. A manufacturer's required circuit size overrides any general table.
- Check the terminal rating on the breaker, the panel lugs and the equipment. Use the 60 °C or 75 °C column that matches the lowest rated part.
- Identify the cable type. NM (Romex) cable is limited to the 60 °C column by NEC 334.80, while conductors in conduit are usually rated 75 °C or higher.
- Measure the one-way distance from the panel to the load, then check voltage drop with the table or the calculator. If the run is long, go up one size.
- Confirm the design with your local code, the authority having jurisdiction and a licensed electrician before you cut wire or install a breaker.
This is general information based on NEC tables, not a permit or an installation plan. Local amendments, the equipment nameplate and an inspector decide what is acceptable. Read the disclaimer.