What Gauge Wire for a 200-Amp Service?
Use 2/0 AWG copper or 4/0 AWG aluminum for 200-amp residential service entrance per NEC 310.12 dwelling exception.
For a 200-amp residential service entrance, per NEC 310.12:
- 2/0 AWG copper (175A at 75°C from Table 310.16, allowed for 200A under §310.12 dwelling exception)
- 4/0 AWG aluminum (180A at 75°C, allowed for 200A under §310.12)
For a non-dwelling 200A feeder or downstream sub-panel, use NEC 310.16 directly:
- 3/0 AWG copper (200A at 75°C)
- 250 kcmil aluminum (205A at 75°C)
NEC 310.12 dwelling reduction at 200A
| Standard (310.16, 75°C) | Dwelling (310.12) | Savings |
|---|---|---|
| 3/0 copper | 2/0 copper | 1 trade size smaller |
| 250 kcmil aluminum | 4/0 aluminum | 1 trade size smaller |
The 83% rule applied to 200A = 166A minimum conductor capacity. 2/0 copper at 175A and 4/0 aluminum at 180A both clear that threshold.
Service entrance configuration
A typical 200A residential service includes:
- 2 × 2/0 copper (or 4/0 aluminum) — line 1 and line 2 (hots)
- 1 × 2/0 copper (or 4/0 aluminum) — neutral
- Grounding electrode conductor (GEC) sized separately per NEC 250.66 (4 AWG copper for 200A service)
Conduit fill
200A service entrance conductors in conduit:
| Material | Configuration | Conduit Area | Fill % | Min conduit |
|---|---|---|---|---|
| 2/0 copper THHN × 3 | 3 × 0.2223 = 0.667 in² | 1.668 in² needed @ 40% | 2-inch EMT (3.356 in²) at 19.9% | 2" EMT |
| 4/0 aluminum × 3 | 3 × 0.3237 = 0.971 in² | 2.428 in² needed @ 40% | 2-inch EMT at 28.9% | 2" EMT |
2-inch EMT fits both options easily. 1-1/2" EMT (2.036 in² interior) fits 2/0 copper at 32.8% but is too small for 4/0 aluminum at 47.7%.
Ampacity derating
If service entrance is run with more than 3 current-carrying conductors (rare for 200A residential service), apply NEC 310.15(C)(1):
- 4 CCCs: × 0.80 — 2/0 Cu drops to 140A (insufficient for 200A)
- For shared raceways carrying 200A circuits with other CCCs, upsize one step
Quick reference
- Standard wire: 2/0 copper or 4/0 aluminum (per NEC 310.12 dwelling)
- Standard wire (non-dwelling): 3/0 copper or 250 kcmil aluminum
- Breaker: 200A 2-pole main
- Neutral: Same size as ungrounded conductors (or reduced per NEC 220.61 in some cases)
- GEC: 4 AWG copper to ground rod / Ufer
- Conduit: 2-inch EMT typical for service entrance riser
For larger commercial 200A feeders, see the conduit fill calculator.