WARNING: 4/0 AWG wire is typically used for 200A residential service entrances, large subpanels, or heavy commercial feeders. Working on service entrance conductors involves unmetered, line-side voltage that cannot be shut off by your main breaker. Always coordinate with your local utility to de-energize the drop, use a tested CAT IV voltage meter to verify dead conditions, and note that local AHJ regulations may require a licensed electrical contractor for service upgrades.

If you are pulling 4/0 AWG (also written as 0000 AWG) feeder wire, you are likely building a 200-amp service entrance, wiring a heavy-duty EV charging station, or connecting a high-capacity solar battery bank. The direct answer for standard ampacities under the National Electrical Code (NEC) is as follows: 4/0 AWG Copper is rated for 195A (60°C), 230A (75°C), and 260A (90°C). 4/0 AWG Aluminum is rated for 180A (60°C), 205A (75°C), and 235A (90°C).

However, picking the right number from the chart requires understanding how the NEC applies temperature ratings to your specific lugs, breakers, and ambient environment. Below is the reference data you need to size your conduit, calculate voltage drop, and pass inspection.

The 4/0 AWG Wire Size Chart (NEC Table 310.16 Data)

The following data is extracted from NFPA 70 (NEC) Table 310.16 [formerly 310.15(B)(16)]. This table provides the allowable ampacities for insulated conductors rated up to 2000 volts. How to read this table: The temperature columns (60°C, 75°C, 90°C) refer to the thermal rating of the wire's insulation (e.g., TW is 60°C, THW/THWN is 75°C, THHN/XHHW-2 is 90°C). The values below assume an ambient air temperature of 30°C (86°F) and no more than three current-carrying conductors in a raceway.

Table 1: 4/0 AWG and Adjacent Sizes (Source: NEC Table 310.16)
Size (AWG/kcmil) Material 60°C (140°F) 75°C (167°F) 90°C (194°F) Area (kcmil) Approx. Bare Diameter
2/0 Copper 175A 195A 225A 133.1 0.414"
3/0 Copper 200A 225A 260A 167.8 0.464"
4/0 Copper 195A 230A 260A 211.6 0.519"
4/0 Aluminum 180A 205A 235A 211.6 0.519"
250 kcmil Copper 215A 255A 290A 250.0 0.565"
250 kcmil Aluminum 170A 205A 235A 250.0 0.565"

Bookmark this section: For a standard 200A residential service using copper, you will look at the 4/0 Copper 75°C row (230A). For aluminum service entrance cable (like SER), you will look at the 4/0 Aluminum 75°C row (205A).

Which Column Applies to Your Installation?

The most common mistake DIYers and junior electricians make is looking at the 90°C column because it offers the highest ampacity, and then sizing their breaker based on that number. In almost all residential and commercial scenarios, you must use the 75°C column for your final termination ampacity.

Here is the physical reality: while the THHN insulation on your 4/0 wire might be rated for 90°C, the lugs on your circuit breakers, disconnect switches, and panelboards are typically only tested and rated for 75°C. According to NEC 110.14(C), the ampacity of the conductor cannot exceed the temperature rating of the termination device. If you push 260A (the 90°C rating) through a 75°C rated breaker lug, the lug will overheat, degrade the mechanical spring tension, and eventually cause a thermal failure or fire, even if the wire insulation itself survives.

The 60°C Column Exception: You are only forced down to the 60°C column (195A for Copper) if you are connecting to equipment specifically marked for 60°C, or if you are using older NM-B (Romex) cable for the entire run. However, NM-B is not manufactured in 4/0 AWG; at this size, you are pulling individual THHN/THWN-2 conductors in conduit or using SER/USE-2 cable, which defaults to the 75°C column.

How Derating Modifies the Base 4/0 AWG Value

The base values in the manufacturer ampacity charts and the NEC table assume ideal conditions: an ambient temperature of 30°C (86°F) and no more than three current-carrying conductors bundled together. When reality deviates from this, you must apply derating factors. Crucially, derating calculations always start from the 90°C column, provided your wire insulation is rated for it.

Example 1: Ambient Temperature Derating
Imagine you are running 4/0 AWG THHN copper feeders through an unventilated attic in a southern climate where the ambient temperature reaches 113°F (45°C). According to NEC Table 310.15(B)(1), the correction factor for 90°C insulation at 41-45°C is 0.82.
Calculation: 260A (90°C base) × 0.82 = 213.2A.
Since 213.2A is still greater than your 200A load, the wire is compliant. However, if that attic hits 122°F (50°C), the factor drops to 0.75. 260A × 0.75 = 195A. Your wire is now undersized for a 200A breaker, and you must upsize to 250 kcmil.

Example 2: Conduit Fill (Bundle) Derating
If you pull four current-carrying conductors in a single PVC conduit (e.g., two ungrounded hots, a neutral that carries unbalanced current, and a fourth wire for a secondary circuit), NEC Table 310.15(C)(1) requires an 80% adjustment factor.
Calculation: 260A × 0.80 = 208A. This is sufficient for a 200A service, but leaves very little headroom for continuous loads.

Note: Equipment grounding conductors (bare copper or green) do not count as current-carrying conductors for derating purposes.

What the 4/0 AWG Chart Cannot Tell You

Ampacity charts only tell you if the wire will melt or catch fire under a given load. They do not account for voltage drop or physical installation constraints, both of which frequently force an upsizing of 4/0 feeders.

Voltage Drop Over Distance

The NEC recommends (via Informational Note in 210.19 and 215.2) keeping voltage drop under 3% for branch circuits and feeders to ensure equipment operates efficiently. 4/0 AWG has a cross-sectional area of 211,600 circular mils (kcmil).

  • Copper 4/0 at 200A (240V): You can run approximately 180 feet before hitting a 3% drop (7.2V).
  • Aluminum 4/0 at 200A (240V): Because aluminum has higher resistance, you will hit the 3% drop threshold at roughly 110 feet.

If your subpanel is 250 feet away from the main service, 4/0 Aluminum will result in a ~6.8% voltage drop. Your 240V tools will see only 223V, causing motors to run hot and trip internal thermal overloads. In this scenario, you must ignore the ampacity chart's permission to use 4/0 and upsize to 300 kcmil or 400 kcmil Aluminum purely to mitigate voltage drop.

Physical Handling and Conduit Fill

4/0 AWG wire is exceptionally stiff. A 500-foot spool of 4/0 copper weighs over 300 pounds. When pulling this wire through conduit, you must adhere to strict physical limits:

  • Conduit Sizing: Three 4/0 AWG THHN conductors plus a 4 AWG ground require a minimum of 2-inch Schedule 40 PVC conduit (based on NEC Chapter 9, Table 1 for 40% fill). Do not attempt to cram this into 1.5-inch conduit; the pulling tension will damage the insulation and stretch the copper.
  • Bending Radius: You cannot bend 4/0 wire tightly by hand. Use a heavy-duty ratcheting wire cutter (like the Klein Tools 63050) for clean cuts, and use factory-swept conduit bends or large radius LL/LR conduit bodies. Sharp 90-degree bends pulled on-site will kink the wire and fail inspection.
  • Termination Torque: Lugs accepting 4/0 wire require significant torque to ensure a low-resistance connection. Always use a calibrated torque wrench set to the manufacturer's specified inch-pounds (often found on the breaker or lug label) rather than "tightening until it feels right." Loose 4/0 connections are a primary cause of thermal arcing in 200A panels.