Southwire 15 ft. 12/3 Black/White/Green Solid CU THHN Tri-Wire

Why I reached for this tri‑wire

I needed a quick, tidy way to run a short 20‑amp branch circuit: one new switch controlling exterior lights and a convenience outlet added to the same box. Rather than buying three separate conductors and hoping the store had the colors I wanted, I tried the Southwire 12/3 THHN tri‑wire. It’s a simple idea—three 12 AWG solid copper conductors, color‑coded black, white, and green, twisted together on a small spool—and for small projects it’s exactly the sort of convenience that saves time.

What you get

• Three 12 AWG solid copper conductors: black (hot), white (neutral), green (equipment ground).
• THHN insulation, rated to 600 volts.
• A compact 15‑foot length on a plastic spool.

This is not a cable assembly; it’s three individual THHN conductors packaged together. That means it’s intended for use in raceways (EMT, PVC, flexible metallic conduit, etc.) and other applications where individual conductors are appropriate. If you’re used to pulling singles, the difference here is simply that the three colors you need for a basic 120‑volt branch circuit are already bundled and ready to go.

Build quality and handling

The copper is bright and consistent, and the insulation print is clear and easy to read. The THHN jacket feels slick, which is exactly what you want when you’re pulling through conduit. On my spool, the twist between the conductors was even, neither too loose nor aggressively tight.

The plastic spool arrived intact but a bit scuffed, and the wind wasn’t perfectly factory‑neat, though it didn’t affect usability. The 15‑foot length was accurate by my tape. For storage, the small spool is tidy on a shelf or in a tote, and it beats wrangling three separate coils for quick jobs.

Because these are solid conductors, they hold shape once bent and they terminate cleanly under device screws. That’s an advantage at receptacles and switches. The trade‑off is flexibility: solid #12 doesn’t love sharp bends or crowded boxes, and it has “memory,” especially when it’s been twisted together.

Installation experience

I ran this through 1/2‑inch EMT with two 90s and a shallow offset. My plan was to pull all three as‑bundled with a single fish tape. It worked, but I’ll share two tips:

• Pre‑tape the lead ends flat. I aligned the black, white, and green side‑by‑side and taped them over several inches to form a smooth head, then tied to the fish tape. This kept the twist from growing into a bulky knot at the front of the pull.
• Use a dab of wire lube. THHN is slick, but lube made the bends painless.

On a second short run with tighter geometry, I separated the three conductors, straightened them by hand, and taped them flat together before pulling. That method reduced the “corkscrew” tendency you get from the factory twist and made the pull feel lighter. The trade‑off is that once you untwist them, the wires never go perfectly straight again—cosmetic only, but noticeable when you’re striving for tidy box work.

At the terminations, solid #12 did what solid #12 does: it lands firmly under side screws and holds shape for neat service loops. Color correctness is baked in, so there’s less chance of grabbing the wrong spool or marking a spare color with tape. For simple two‑wire plus ground circuits, that’s a small but real time saver.

Code and application notes

• Location: These are THHN conductors. Use them in conduit and other approved raceways. If you’re working in a wet location, verify the wet‑location rating printed on the wire or choose a conductor specifically listed for wet locations. Don’t run singles loose in walls or use them as a flexible cord.
• Circuit sizing: 12 AWG copper is typical for 20‑amp branch circuits. Pair it with the appropriate breaker and devices.
• Conduit fill and derating: You’ve got two current‑carrying conductors (black and white) plus a green equipment grounding conductor. Check conduit fill tables for your raceway size and any additional conductors sharing that run.
• Inspector preferences: In many residential settings, inspectors like solid conductors on device terminations. This wire fits that expectation.

None of this is unique to this product, but it’s worth keeping in mind if you’re used to pulling stranded or if you’re new to singles in raceway.

Where it shines

• Short runs and add‑ons. Fifteen feet is a sweet spot for a new device to the nearest junction, a short whip to a ceiling box, or replacing a goofy old timer with a switch/outlet combo without buying bulk lengths.
• Clean color‑coding. Black, white, green is the everyday trio for 120‑volt work, and having them together on one spool reduces prep time.
• Solid terminations. If you prefer landing solid conductors on screw terminals, this is ideal.

Limitations and gotchas

• Twisted memory. The factory twist is convenient until it isn’t. In simple straight runs, it’s fast. In tight 1/2‑inch conduit with multiple bends, that twist adds a bit of friction and tends to spin. If you anticipate a tough pull, separate and tape the conductors flat before pulling.
• Flexibility. Solid #12 is stiffer than stranded. If you’re packing a lot into a small box or making tight offsets, stranded THHN might be the friendlier choice.
• Length. Fifteen feet is perfect for small jobs and pigtails, but you’ll outgrow it fast on longer runs. If you’re doing more than two short pulls, you may be better off with individual conductors in longer lengths.
• Packaging. My spool was serviceable but not pristine. If you’re expecting a showroom‑perfect wind, temper that expectation.

Value

For small projects, the convenience is the value. I didn’t have to stand at a store counter waiting for cuts in three colors, and I didn’t end up with three partly used coils I’d forget to label. As a one‑spool solution for quick 20‑amp runs, it makes sense. If your work routinely exceeds 15 feet or involves complex conduit paths, buying singles in longer lengths (or switching to stranded) becomes more cost‑effective and easier to pull.

Practical tips

• If you keep the trio twisted, keep your pull head compact. Align, tape flat, then tie the fish tape.
• If you untwist, run a hand down each conductor to knock out the worst of the coil, then tape them side‑by‑side in a low‑profile bundle.
• Use wire lube on any pull with more than one 90 or a tight radius.
• Leave generous service loops in the box; solid #12 is less forgiving if you need to re‑land a device later.
• Label the leftover end and tuck the spool back into your electrical bin—you’ll use it again.

Bottom line

The Southwire 12/3 THHN tri‑wire does exactly what it promises: three properly color‑coded, solid 12 AWG copper conductors on a handy 15‑foot spool, ready for branch‑circuit work in raceway up to 600 volts. The quality of the copper and insulation is solid, termination is straightforward, and the convenience factor is real for small jobs. The twist can be a minor nuisance in tight conduit, and solid conductors aren’t everyone’s favorite for pulling, but both are manageable with basic technique.

Recommendation: I recommend this tri‑wire for electricians and DIYers who tackle short, straightforward 20‑amp runs in conduit and want a clean, ready‑to‑pull set of conductors without a trip to the wire rack. It saves a bit of time, keeps color‑coding simple, and lands nicely on device screws. If you’re planning long or bend‑heavy pulls, or you prefer the flexibility of stranded wire, buy individual THHN conductors in longer lengths instead.