Do I need 2/0 or 3/0 copper for 200 amps?

Use 2/0 copper for a dwelling service or whole-dwelling feeder that meets every NEC 310.12 condition. Use 3/0 copper for the plain 75 °C Table 310.16 method when the allowance does not apply.

What is the aluminum service wire size for 200 amps?

For a qualifying dwelling service, use 4/0 aluminum. Without the allowance, the verified 75 °C table requires 250 kcmil aluminum for 200 A.

Can I use 4/0 aluminum for a 200 amp service?

Yes, when the 200 A installation qualifies for NEC 310.12 and the conductors and equipment are suitable for aluminum. The 83% requirement is 166 A, and 4/0 aluminum is rated 180 A at 75 °C.

Does Romex qualify for the 83% dwelling-service rule?

No. NM/Romex is a 60 °C assembly, and the dwelling-service allowance requires conductors rated 75 °C or better.

🏠 What Size Wire for a 200 Amp Service?

2/0 copper, 3/0 copper, and 4/0 aluminum can all be correct — but under different sizing methods. 🇨🇦 Canadian version

Why the internet gives three answers

2/0 AWG copper is the NEC 310.12 dwelling-service answer. 3/0 AWG copper is the plain 310.16 answer at 75 °C when that allowance does not apply. 4/0 AWG aluminum is the dwelling-service aluminum answer; the plain 75 °C table instead selects 250 kcmil aluminum.

200 A × 83% = 166 A → 2/0 AWG copper (175 A at 75 °C); 4/0 AWG aluminum (180 A at 75 °C).

Plain 75 °C table: 200 A → 3/0 AWG copper (200 A) or 250 kcmil aluminum (205 A).

When the 83% answer is allowed

Dwelling service or a feeder carrying the entire dwelling load only — never a branch circuit or a non-dwelling installation.
The service or feeder rating must be from 100 A through 400 A.
No ampacity adjustment or correction factors can be required.
Conductors must be rated 75 °C or better. NM/Romex is a 60 °C assembly, so it is out.

Distance can move the answer again

This table begins with the NEC 310.12 dwelling-service minimum, then raises the conductor when the calculated drop would exceed the 3% planning target. It uses 240 V, the full 200 A rating, and one-way distance.

200 A dwelling service at 240 V

Material	50 ft	100 ft	150 ft	200 ft	250 ft	300 ft
Copper	2/0	2/0	2/0	3/0	4/0	250 kcmil
Aluminum	4/0	4/0	4/0	250 kcmil	300 kcmil	400 kcmil

Wire Size calculator · Ampacity Check tool

Why aluminum is common in service work

Aluminum is widely used for service conductors because its lower weight and material cost matter at large sizes. Use listed conductors and terminals, follow the equipment instructions, and have the complete service design checked locally.

100-amp service wire size guide · Sub-panel wire size guide · Ampacity Check tool

200-amp service wire size FAQ

Do I need 2/0 or 3/0 copper for 200 amps?: Use 2/0 copper for a dwelling service or whole-dwelling feeder that meets every NEC 310.12 condition. Use 3/0 copper for the plain 75 °C Table 310.16 method when the allowance does not apply.
What is the aluminum service wire size for 200 amps?: For a qualifying dwelling service, use 4/0 aluminum. Without the allowance, the verified 75 °C table requires 250 kcmil aluminum for 200 A.
Can I use 4/0 aluminum for a 200 amp service?: Yes, when the 200 A installation qualifies for NEC 310.12 and the conductors and equipment are suitable for aluminum. The 83% requirement is 166 A, and 4/0 aluminum is rated 180 A at 75 °C.
Does Romex qualify for the 83% dwelling-service rule?: No. NM/Romex is a 60 °C assembly, and the dwelling-service allowance requires conductors rated 75 °C or better.