10/3 UF wire is a copper underground feeder cable with three 10 AWG conductors plus a ground, built for direct burial to outdoor lamps, pumps, and outbuildings.
A buried run to a shed, lamp, or well pump needs cable that can sit in wet soil for decades. Southwire’s UF-B copper cable is made for that, and 10/3 carries the extra conductor 240-volt loads and multi-switch setups need. Here’s what the cable is, what the numbers mean, where it can legally go, and the mistakes that trip up first-time installers.
What Do The Numbers 10/3 Mean?
The “10” is the conductor gauge; the “3” is the count of current-carrying wires — three 10 AWG conductors plus a bare ground. Gauge runs backward from intuition: 10 AWG is thicker than 12 AWG, so it carries more current with less voltage drop over distance.
The three conductors determine what you can power. A 10/2 cable gives one hot, one neutral, and a ground — enough for a 120-volt circuit. The third conductor in 10/3 adds a second hot leg or a traveler wire, enabling 240-volt equipment and three-way switching on a single run.
- Conductor size: 10 AWG, solid copper
- Conductor count: three, plus a 1×10 ground
- Voltage rating: 600 volts
- Jacket: 30 mils, with 25 mils of insulation on each conductor
- Overall dimensions: roughly 0.215 x 0.727 inches
Southwire lists 90°C conductor temperature use, but ampacity for interior branch circuits is limited to 60°C conductors. Don’t size a breaker off the 90°C column when the cable runs inside a building.
What Is 10/3 UF Wire Used For?
Southwire documents UF-B as a feeder to outside post lamps, pumps, and similar loads supplied from an existing building distribution point — covering many residential and agricultural jobs.
Typical installations include a detached garage or workshop subpanel, a well or sump pump, landscape and post lighting, and outdoor receptacle circuits. UF-B is also permitted for interior branch-circuit wiring in residential and agricultural buildings where the National Electrical Code allows nonmetallic cable under NEC 334.10(B). The jacket resists moisture and light, separating it from standard NM-B indoor cable.
The practical advantage is direct burial — no conduit requirement for the buried span in most residential applications saves material cost and trench labor. Before cutting into a spool, match load to cable: amps, run length, and voltage drop decide whether 10 AWG is right or the job needs 8 AWG.
10/3 UF Wire Specs And Retail Packages
Southwire publishes the specs and package listings below. Prices shift with copper markets, so confirm at purchase.
| Package Or Spec | Detail | Listed Price |
|---|---|---|
| 50 ft. spool | 10/3 gray solid copper UF-B with ground | $246 |
| 100 ft. spool | Product number 13059122 | $357 ($3.57/ft.) |
| 250 ft. spool | Product number 13059104 | $434 |
| By-the-foot cut | Product number 13059101 | Sold per foot |
| Voltage rating | 600 volts | — |
| Jacket thickness | 30 mils jacket, 25 mils insulation | — |
| Ground conductor | 1×10 | — |
If you’re comparing spool lengths or weighing 10/3 against another gauge, a tested 10/3 UF wire roundup lays the options side by side.
Note the gap between 100 and 250 feet: at $434 for 250 feet versus $357 for 100 feet, the longer spool costs far less per foot. Buying cut lengths rarely beats a spool past about 150 feet. Southwire’s UF-B copper cable product page carries the full spec sheet.
What Mistakes Sink A UF-B Install?
Most failures trace to treating UF-B as universal outdoor wire rather than a code-scoped product. Southwire ties its use to NEC-permitted applications and specific feeder and branch-circuit contexts, so it’s not a blanket substitute for every buried or wet-location job.
- Wrong material assumed: this is solid copper at 10 AWG. Aluminum cable and other gauges such as 12/2 or 8/3 are different products with different ampacity.
- Ampacity read from the wrong column: interior branch circuits are limited to 60°C conductors even though the cable can operate at 90°C.
- Burial depth guessed: verify depth, protection, and load before trenching. Moisture and light resistance doesn’t replace code-compliant burial practice.
- Breaker sized before the load: confirm circuit amps, run length, and voltage drop first, then size breaker and cable together.
Local code compliance decides the final answer on all these points. Check with the authority having jurisdiction before the trench goes in.
FAQs
Can UF-B cable be buried without conduit?
Yes, in most residential direct-burial applications. UF-B is rated for underground use, which is the main reason it exists. Depth requirements and protection rules still apply and vary by location, so confirm the required burial depth before backfilling.
Is 10/3 the same as 10/2?
No. Both use 10 AWG conductors, but 10/2 has two current-carrying wires and 10/3 has three. The extra conductor allows 240-volt circuits or three-way switching on a single run. Choose based on load, not habit.
How many amps can 10 AWG copper carry?
Ampacity depends on the temperature column and application. For interior branch circuits, Southwire limits ampacity to the 60°C conductor rating rather than the cable’s 90°C rating. Size the breaker from the correct column for your installation type and confirm against local code.
References & Sources
- Southwire. “UF-B Copper Cable — 10/3 Gray Solid CU UF-B W/G Wire.” Source for product specs, listed prices, feeder applications, and interior branch-circuit ampacity limits.
- Southwire. “UF-B Copper Cable — 250 ft. 10/3 Gray Solid CU UF-B W/G Wire.” Confirms direct-burial use and residential and agricultural building applications.
- Southwire. “UF-B Copper Cable — By-The-Foot 10/3 Gray Solid CU UF-B W/G Wire.” Source for the by-the-foot product listing and product number.
