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What size wire for 200 amps?

3/0 AWG copper — at 75 °C terminals, NEC Table 310.16. Aluminum needs a conductor larger than 4/0 at this load.

A 200 A circuit needs 3/0 AWG copper, rated 200 A at 75 °C. At this size the conductors are single conductors in conduit or SER cable; NM-B is not manufactured heavy enough to apply.

Safety first. This is a starting point before derating, not a load calculation. Wire sizing affects fire and shock safety — verify against the current NEC and have circuits designed or reviewed by a licensed electrician for your jurisdiction.

200 amp wire size by material and terminal rating

Minimum conductor size for a 200 amp circuit by material and terminal temperature rating.
Material 60 °C (NM-B) 75 °C (typical) 90 °C
copper over 4/0 3/0 AWG (200 A) 3/0 AWG (225 A)
aluminum over 4/0 over 4/0 4/0 AWG (205 A)

Sizes are the smallest conductor whose ampacity and NEC 240.4(D) breaker cap both reach 200 A, before any derating. Use the 75 °C column unless every terminal, breaker and device in the circuit is rated otherwise (NEC 110.14(C)).

If the load runs continuously

A load operating for three hours or more is a continuous load, and NEC 210.19(A)(1) requires the conductor to be sized at 125% of it — 200 A becomes 250 A for sizing purposes. That moves this circuit to 4/0 AWG copper , one or more sizes above the 3/0 AWG the plain table suggests. EV chargers, electric heat and commercial lighting are the loads this catches most often.

How far can a 200 amp circuit run?

The table above only prevents overheating. On a long run the limit is voltage arriving at the far end, and it bites well before ampacity does. These are the longest one-way runs for 3/0 AWG copper at 200 A within the 3% drop recommended by the NEC 210.19(A) informational note — and what going up to 4/0 AWG buys you.

Maximum one-way run length for a 200 amp circuit by system voltage and conductor size.
System Typical use 3/0 AWG 4/0 AWG
120 V standard receptacle and lighting circuits 146 ft 184 ft
240 V ranges, dryers, EV chargers, feeders 291 ft 367 ft
12 V DC automotive, marine, solar and battery runs 15 ft 18 ft

Single-phase, one-way distance, copper at 20 °C. Aluminum reaches its limit at roughly 60% of these distances. The 3% target is a recommendation, not a code requirement.

What runs on a 200 amp circuit

The catch at 200 amps

200 A is the most-searched service size and the answer is almost never 4/0 copper. Dwelling services use NEC 310.12, where 200 A is 2/0 copper or 4/0 aluminum — and aluminum wins on cost nearly every time.

Working the other way round? See how many amps 3/0 AWG carries , including its diameter, resistance and full run-length table.