| Rule | Copper | Aluminum |
|---|---|---|
| 75°C column — NEC Table 310.16 | 3/0 AWG | 250 kcmil |
| Dwelling service or main feeder — NEC 310.12 (83% = 166A) | 2/0 AWG | 4/0 AWG |
Above 100A, NEC 110.14(C)(1)(b) allows the 75°C column when terminations are rated 75°C, which is standard for this equipment.
This is the most misquoted number in residential wire sizing. In NEC Table 310.16, 4/0 AWG aluminum is rated 180 A at 75°C — not enough for a 200-amp circuit. 4/0 aluminum is nevertheless the standard 200-amp residential service conductor, and both facts are correct, because two different rules apply:
| Application | Governing rule | Aluminum for 200 A |
|---|---|---|
| Dwelling service entrance, or the feeder carrying the entire dwelling load | NEC 310.12 (the “83% rule”) | 4/0 AWG |
| Everything else — sub-panel feeders, commercial feeders, branch circuits | NEC Table 310.16 | 250 kcmil |
NEC 310.12 permits service and main-power feeder conductors for a one-family dwelling to be sized at 83% of the service rating: 200 A × 0.83 = 166 A, and 4/0 aluminum’s 180 A rating covers that. The allowance exists because a dwelling never draws its full service rating continuously. It applies only to the conductors carrying the entire dwelling load.
For a 200-amp sub-panel feeder to a garage or shop, a commercial feeder, or any circuit that is not the dwelling’s main power feeder, 310.12 does not apply and you need 250 kcmil aluminum (205 A at 75°C). For copper, 3/0 AWG (200 A at 75 °C) satisfies either rule.
Residential service entrance, commercial feeders
| Diameter | 10.4049 mm (0.409642") |
| Area | 85.0288 mm² |
| Resistance at 20°C | 0.2028 Ω/km |
| Weight | 761.858 kg/km |
| Ampacity (75°C) | 200 A |
Important: For long wire runs, you may need to upsize the wire to compensate for voltage drop. NEC recommends keeping voltage drop under 3% for branch circuits. Use our voltage drop calculator to check.
| One-way run | Drop | % of 240V | Verdict |
|---|---|---|---|
| 25 ft | 0.77 V | 0.3% | Within the 3% branch-circuit target |
| 50 ft | 1.53 V | 0.6% | Within the 3% branch-circuit target |
| 75 ft | 2.30 V | 1.0% | Within the 3% branch-circuit target |
| 100 ft | 3.06 V | 1.3% | Within the 3% branch-circuit target |
| 150 ft | 4.60 V | 1.9% | Within the 3% branch-circuit target |
| 200 ft | 6.13 V | 2.6% | Within the 3% branch-circuit target |
Sizing for a 200-amp aluminum feeder depends on the application — see the NEC 310.12 explanation above. A dwelling service or main power feeder uses 4/0 AWG; any other 200-amp feeder needs 250 kcmil (205 A at 75°C).
| Dwelling service / main power feeder | 4/0 AWG aluminum — NEC 310.12 |
| Sub-panel or commercial feeder | 250 kcmil aluminum — NEC Table 310.16 |
| 4/0 aluminum ampacity (75°C) | 180 A |
| 250 kcmil aluminum ampacity (75°C) | 205 A |
| 4/0 aluminum resistance | 0.0753 Ω/1000 ft |
Under NEC Table 310.16 at 75°C, a 200-amp circuit needs 3/0 AWG copper (200A) or 250 kcmil aluminum (205A). For a one-family dwelling service or main power feeder, NEC 310.12 allows sizing at 83% (166A): 2/0 AWG copper or 4/0 AWG aluminum, which is why 4/0 aluminum is the standard 200A residential service conductor.
A 200-amp circuit uses a 200A double-pole breaker. It protects 3/0 AWG copper or 250 kcmil aluminum under Table 310.16, or 2/0 copper or 4/0 aluminum on a dwelling service sized under NEC 310.12.
A 200-amp dwelling service entrance uses 2/0 AWG copper or 4/0 AWG aluminum under NEC 310.12. Aluminum is standard for 200A service entrance conductors because of significant cost savings. 4/0 aluminum is rated 180 A in Table 310.16, below the 200 A service rating — it qualifies here only because NEC 310.12 lets a dwelling service conductor be sized at 83% of the service rating (200 A × 0.83 = 166 A). A 200-amp sub-panel feeder does not get that allowance and needs 250 kcmil aluminum. The conductors connect the utility meter to the main breaker panel.
Yes — a 200-amp panel easily handles these loads simultaneously. A 48A EV charger needs a 60A breaker (30% of the panel rating), a range uses a 50A breaker (25%), and a dryer uses a 30A breaker (15%). Total demand rarely exceeds 120–140A at any moment due to load diversity, leaving ample headroom.