A 200 amp dwelling service takes 2/0 AWG copper or 4/0 AWG aluminum, while a feeder or subpanel usually needs 3/0 copper or 250 kcmil aluminum.
The NEC splits the job: a dwelling service gets its own allowance, a feeder or subpanel does not, and the two answers land a full size apart. Size too small and conductors run hotter than their terminations are rated for; use the feeder number on a service job and you overspend on copper. Three tables drive it: 310.12 for dwelling services, 310.16 for general feeders, and 250.122 for the equipment grounding conductor.
What Size Wire For A 200 Amp Breaker?
A 200 amp single-phase dwelling service is commonly wired with 2/0 AWG copper or 4/0 AWG aluminum per NEC Table 310.12. A 200 amp feeder or subpanel, where that allowance does not apply, is sized at 3/0 AWG copper or 250 kcmil aluminum from Table 310.16 at the 75°C column.
“Service” means conductors from the utility’s drop to the main panel. Everything past that panel is a feeder, and a feeder does not get the smaller number.
| Part Of The Job | Copper | Aluminum |
|---|---|---|
| 200 amp dwelling service conductors (Table 310.12) | 2/0 AWG | 4/0 AWG |
| 200 amp feeder or subpanel conductors (Table 310.16, 75°C) | 3/0 AWG | 250 kcmil |
| Equipment grounding conductor for a 200 amp breaker (Table 250.122) | 6 AWG | 4 AWG |
Two rows describe the same 200 amps and still land on different wire — the whole reason this question has two answers. These are base numbers. Ambient temperature and the number of current-carrying conductors in a raceway can lower what a given wire may carry, so the final call belongs to whoever signs off on the install.
200 Amp Service Wire Size: Where The Rules Change
The dwelling allowance in Table 310.12 makes a 200 amp service wire size smaller than a 200 amp feeder of the same amperage. It covers service conductors feeding a single dwelling and stops there — a subpanel feeder or commercial run falls back to Table 310.16.
Ampacity values hold only at the termination temperature used to look them up. These examples use the 75°C column, the rating most standard equipment terminations carry. If lugs are listed for 60°C, allowable ampacity drops and the conductor may need to grow a size. A breaker’s label tells you its protection rating, not its wire size; conductor size follows the circuit’s role, which is why the same 200 amp device can sit on two different wire sizes in one building.
Utility rules can push the size up. The cable supplier guidance on wiring a 200 amp service notes that some utilities require larger conductors than the code minimum, so call before ordering. Distance matters too: voltage drop grows with length, and a run already near its ampacity limit may need to go up a size to hold voltage near the 3% most electricians design to. Aluminum adds one more check — lugs and terminations must be listed for aluminum.
Grounding And The Details That Change The Size
A 200 amp breaker label does not lock in a wire size. Conductor sizing turns on what the run does — dwelling service, feeder, or another circuit — plus termination ratings, utility requirements, and local amendments on top of the NEC.
The equipment grounding conductor is sized from the breaker rating using Table 250.122: 6 AWG copper minimum at 200 amps, or 4 AWG aluminum. It stays far smaller than the current-carrying conductors because it only carries fault current briefly.
One common mix-up: feeding a detached garage or shop from a 200 amp breaker in the main panel is a feeder, not a service, so the larger Table 310.16 sizes apply even when the job feels like a service upgrade.
If the breaker itself is still an open question, our tested roundup of 200 amp breakers compares models that pair with these conductor sizes.
The order that covers both cases:
- Decide whether the run is a dwelling service or a feeder.
- Look up ampacity at the temperature rating of your terminations — 75°C in most of these examples.
- For a dwelling service, apply the allowance in Table 310.12.
- For a feeder or any non-dwelling run, size from Table 310.16.
- Size the grounding conductor from the breaker rating using Table 250.122.
Local rules can raise any of these numbers, so confirm the final size with your utility and inspector before the wire is cut.
FAQs
Can I Use 2/0 Copper For A 200 Amp Subpanel?
Not usually. The 2/0 AWG copper figure belongs to the dwelling-service allowance in Table 310.12, which covers service conductors feeding a home. A 200 amp subpanel feeder generally falls under Table 310.16, where 3/0 AWG copper or 250 kcmil aluminum is the commonly cited minimum at the 75°C column.
Does The Grounding Wire Have To Match The Hot Conductors?
No. The equipment grounding conductor is sized from the breaker’s ampere rating, not the current-carrying conductors beside it. On a 200 amp breaker, Table 250.122 puts the minimum at 6 AWG copper, or 4 AWG aluminum — several sizes smaller than the 2/0 or 3/0 AWG conductors in the same run.
Why Do Two Electricians Give Different Wire Sizes?
Often because one is sizing a dwelling service and the other a feeder. The dwelling allowance in Table 310.12 permits smaller conductors than the general Table 310.16 calculation at the same 200 amps. Termination temperature ratings and local utility requirements can shift the number further.
References & Sources
- Nassau National Cable. “Wiring 200 Amp Service: Wire Size Guide and Things To Know.” Source for dwelling-service wiring sizes and the note that utility requirements can exceed the code minimum.
- Ramcorp Wire & Cable. “AWG Wire Gauge Guide.” Reference for AWG and kcmil conductor sizing and termination temperature limits.
- APS Cable. “Ground Wire Sizing Chart.” Supports the 6 AWG copper and 4 AWG aluminum equipment grounding conductor figures for a 200 amp breaker.
