150 Amp Wire Size: What Gauge Wire Do You Need?
NEC-based wire gauge for a 150 ampbreaker — copper and aluminum sizes, ground wire, conduit, and when to upsize for voltage drop.
For a 150 amp circuit or feeder, use 1/0 AWG copper or 3/0 AWG aluminum wire (THWN/THHN at 75°C).
Based on NEC Table 310.16 (75°C column) and, where noted, Table 310.12 for dwelling services. Confirm termination ratings and local amendments before installing.
150 Amp Wire Size at a Glance
| Copper wire size | 1/0 AWG |
|---|---|
| Aluminum wire size | 3/0 AWG |
| Breaker size | 150 amp |
| Ground wire | #6 AWG copper |
| Typical conduit | 2" EMT (four 1/0 THHN conductors) |
Verify conduit fill for your exact conductor count and insulation type with the conduit fill calculator.
Common Uses for a 150 amp Circuit
- 150 amp main services on mid-size homes
- Heavy shop and barn feeders
- Feeders to detached ADUs with electric heat and EV charging
- Small commercial tenant panels
- Elevator and machine feeders
When to Upsize for Voltage Drop
At 240V and a full 150 amp load, 1/0 copper or 3/0 aluminum passes 3% voltage drop near 110 feet. Long rural feeders should be checked at realistic demand: at 100A actual load, the same conductors reach about 165 feet. For 200+ foot runs, 4/0 aluminum or 2/0 copper is the usual step-up.
The NEC recommends (in informational notes to 210.19 and 215.2) keeping voltage drop under 3% on a branch circuit or feeder and 5% total. Ampacity tables ignore distance entirely, so on any run much past 100 feet, check the numbers with the voltage drop calculator before buying wire.
NEC References and Code Notes
- 1/0 AWG copper is rated exactly 150A at 75°C in Table 310.16; 3/0 AWG aluminum is rated 155A at 75°C.
- NEC Table 310.12 lists the same sizes — 1/0 copper or 3/0 aluminum — for a 150A dwelling service, so for 150 amps the standard-feeder answer and the dwelling-service answer happen to match.
- The equipment grounding conductor for a 150 amp feeder is #6 AWG copper per Table 250.122.
- At this size, aluminum’s cost advantage is large — 3/0 aluminum SER or XHHW-2 typically costs less than half of 1/0 copper.
See the NEC code reference for related articles. Always confirm requirements with your local authority having jurisdiction.
Frequently Asked Questions
What size wire for a 150 amp service?
A 150 amp residential service uses 1/0 AWG copper or 3/0 AWG aluminum service-entrance conductors. These sizes satisfy both Table 310.16 at 75°C (1/0 Cu = 150A, 3/0 Al = 155A) and the Table 310.12 dwelling-service allowance, so the answer is the same either way for 150A.
Can 2/0 aluminum carry 150 amps?
No. 2/0 AWG aluminum is rated 135A at 75°C — not enough for a 150 amp breaker on a standard feeder. Even under the Table 310.12 dwelling-service allowance, 150 amps requires 3/0 aluminum. 2/0 aluminum is a fine conductor for a 125 amp feeder, but for 150A, step up to 3/0.
What ground wire for 150 amps?
A #6 AWG copper (or #4 AWG aluminum) equipment grounding conductor per NEC Table 250.122 — the table’s #6 copper row covers overcurrent devices over 100A up through 200A, so 125A, 150A, and 200A feeders all take #6 copper grounds. For the grounding electrode conductor on a 150A service with 1/0 copper service conductors, Table 250.66 calls for #6 copper as well.
Is 150 amp service enough for a modern home?
For homes with gas appliances, usually yes. All-electric homes with a heat pump, electric range, dryer, and a 48A EV charger frequently calculate above 150A. Since panel and labor costs are similar, most services today are built at 200A — but if you have an existing 150A service, a load calculation plus a load-management device for the EV charger often avoids an upgrade.
Related Tools and Wire Size Guides
Wire Sizing Calculator
Calculate the exact wire gauge for any load, voltage, and distance per NEC tables.
Calculate Wire Size →Voltage Drop Calculator
Check whether your run length forces a larger conductor than ampacity alone requires.
Calculate Voltage Drop →Wire Ampacity Chart
Full NEC Table 310.16 ampacities at 60°C, 75°C, and 90°C for copper and aluminum.
View Ampacity Chart →Breaker Size Calculator
Find the right breaker for a given load, including the 125% continuous-load rule.
Size a Breaker →200 Amp Service Wire Size: What Gauge Wire Do You Need?
For a 200 amp residential service, use 2/0 AWG copper or 4/0 AWG aluminum wire (per NEC Table 310.12, the 83% rule for dwelling services).
Read the Guide →30 Amp Wire Size: What Gauge Wire Do You Need?
For a 30 amp circuit, use #10 AWG copper or #8 AWG aluminum wire (THWN/THHN rated at 75°C).
Read the Guide →40 Amp Wire Size: What Gauge Wire Do You Need?
For a 40 amp circuit, use #8 AWG copper or #6 AWG aluminum wire (THWN/THHN rated at 75°C).
Read the Guide →