2/0 copper wire is a thick AWG “00” gauge conductor rated for high-current service, feeder, and branch-circuit work, with typical ampacity ratings from 145A to 195A.
2/0 copper wire (pronounced “two-aught copper”) has been the workhorse for serious electrical jobs for decades: panels, feeders, service conductors, and high-current circuits where thinner cable would run dangerously hot. The “2/0” is American Wire Gauge notation for “00,” a size with a copper conductor roughly 0.4 inches across. Before buying, know that its actual safe current-carrying capacity depends on the insulation type, installation conditions, and the temperature rating of the terminations you connect it to.
If you’re sizing a run for a subpanel or large circuit, the short version is this: 2/0 copper commonly lands at 175A as a usable circuit rating in most installations, while the conductor itself is officially rated higher (195A) at 90°C. The table below breaks down the rated ampacity by insulation temperature class — the single most important spec to understand.
The Core Specs of 2/0 Copper Building Wire
Published 2/0 copper building wire is manufactured as a 19-stranded, bare copper conductor rated for 600 volts with a maximum conductor temperature of 90°C. When properly installed, it is approved for indoor/outdoor use, wet or dry locations, and conduit or raceway applications depending on the insulation type. Common insulation styles include THHN/THWN-2, XHHW-2, and MTW — each designed to handle the same 90°C heat threshold. Most commercial 2/0 copper building wire products have an overall diameter between 0.518 and 0.540 inches, making them roughly 15-20% thicker than 1/0 copper wire. The heavier 2/0 gauge also weighs significantly more per foot — Southwire lists its 2/0 SIMpull THHN/THWN-2 at around 410.6 pounds per 1,000 feet.
Understanding the numbers in product listings:
- 2/0 AWG (or “00”): The gauge size — the thicker the wire, the more current it carries.
- 19-strand bare copper: The standard stranding construction for flexibility and ease of pulling.
- 600V rating: The maximum system voltage this building wire is designed to handle.
- 90°C insulation: The max temperature the insulation can tolerate continuously; but the termination usually limits the usable rating to 75°C.
So How Many Amps Can 2/0 Copper Wire Safely Carry?
Per published ampacity charts, a 2/0 copper conductor with 90°C insulation has a rating of 195A, but the final usable ampacity for most installations is typically lower because equipment terminations (the lugs, breakers, and bus bars) have their own heat limits — most are rated only 75°C. That means a 2/0 copper run feeding a panel or a large breaker will commonly top out at 175A, not the full 195A the wire itself can handle. Below is a practical breakdown of the rated ampacity at each temperature rating:
2/0 Copper Ampacity Chart (Typical Values)
| Temperature Rating | Ampacity | Best For |
|---|---|---|
| 60°C (140°F) | 145A | Older equipment with low temp ratings |
| 75°C (167°F) | 175A | Most modern panels, breakers, and lugs (the common usable rating) |
| 90°C (194°F) | 195A | Used for derating calculations, but rarely the final circuit rating |
| 90°C THHN/THWN-2 usable value | 195A | Only if terminations are rated for 90°C (rare in standard equipment) |
| Typical 75°C termination limit | 175A | What most installations will actually use |
| XHHW-2 insulation variant | 195A (conductor rating) | Wet/dry locations, high-heat environments |
That 195A figure at 90°C matters for derating calculations when multiple current-carrying conductors are bundled together. The conductor’s true limit allows some headroom before applying those correction factors, but the final answer always lands back at the weakest link — usually the 75°C lugs on a breaker or panel. In short: 2/0 copper is generally treated as a 175A wire for practical purposes, despite being formally rated higher.
What You Should Know Before You Buy
Not all 2/0 copper wire is created equal. Let’s be clear: you cannot assume that this gauge conductor is always rated for direct burial, or that every product has the same overall diameter and weight. The 19-strand conductor in Southwire’s popular SIMpull THHN/THWN-2 product uses a 0.405-inch conductor, and the overall cable measures about 0.524 inches because of the insulation and jacket. Allied Wire & Cable’s XHHW-2 product, by contrast, lists a nominal overall diameter of 0.540 inches and has a weight of 452 pounds per thousand feet. These are two different, perfectly valid products for the same gauge.
Here are the most common mistakes people make when selecting this wire:
- Confusing material: 2/0 copper and 2/0 aluminum have very different ampacity ratings; copper carries more current.
- Using the 90°C number as the final circuit rating: Without checking termination ratings, you can overload a breaker or panel lug.
- Assuming all 2/0 wire is for direct burial: Only specific insulation types and listings allow underground installation without conduit.
- Assuming identical dimensions and weight: Each manufacturer’s insulation system slightly changes the cable’s outer measurements and weight per foot.
Once you know the gauge, insulation type, and actual length of the run you need, you can confidently choose the right product. For a side-by-side breakdown of the most reliable and best-reviewed 2/0 copper wire options on the market, check out our tested roundup of the best 2/0 copper wire — it will help you pick the exact type and brand for your specific job without the guesswork.
FAQs
Is 2/0 copper wire the same as 00 gauge wire?
Yes. “2/0” and “00” are simply two different ways of writing the same American Wire Gauge size. The “0” notation for large wires uses a slash to show the count of zeros; 2/0 (two-aught) is one size larger than 1/0 and one size smaller than 3/0.
Can 2/0 copper wire be buried directly in the ground?
Only if the insulation type is specifically rated for direct burial, like UF-B or certain listed cable styles. Standard THHN/THWN-2 wire is rated for wet locations but generally requires conduit for underground runs. Always check the product labeling and local electrical code before installing any cable underground.
What size breaker is typical for 2/0 copper wire?
Because of the 75°C termination limit on most breakers and panels, the typical maximum breaker size for 2/0 copper is 175A. The conductor itself can handle 195A at 90°C, but that rating is rarely usable unless the equipment lugs are explicitly rated for 90°C.
References & Sources
- Southwire. “SIMpull THHN/THWN-2 Copper Product Page.” Provides spec details for 2/0 copper conductor construction.
- CerroWire. “Ampacity Charts.” Official source for copper ampacity by temperature rating.
- All About Circuits. “Copper Wire Ampacity Table.” Reference for current-carrying capacity of copper conductors.