Southwire 25 ft. 12/3 Black/White/Green Solid CU THHN Tri-Wire

I’m a fan of anything that trims time from a conduit pull without compromising code compliance. Southwire’s 12/3 THHN tri-wire did exactly that for me on a couple of short branch-circuit runs where I needed a hot, neutral, and equipment ground in a clean, manageable bundle.

What it is

This is a 25-foot coil of three individual 12 AWG solid copper THHN conductors—black, white, and green—twisted together at the factory. Each conductor is individually insulated and nylon-jacketed as you’d expect from THHN, and the assembly is simply a convenience bundle, not a multi-conductor cable with an overall sheath. It’s rated to 600 volts and intended for use in conduit or other raceways feeding outlets, switches, or similar loads.

If you’ve ever bought three separate spools or tried to pull loose singles from a cart, you’ll immediately understand the appeal: the color set you need, pre-bundled for one pull, in a length that makes sense for small projects.

Build and materials

The conductors are true 12 AWG solid copper with standard THHN insulation and nylon jacket. The nylon provides a slick surface that resists abrasion on bends and fittings, and it strips cleanly with a sharp pair of strippers without tearing or “hairing” the jacket. The twist pitch is tight enough to keep the conductors together without creating a rope that fights you in the raceway. There’s no outer sheath—just three singles twisted together—so you maintain normal conduit fill and heat dissipation assumptions.

Solid THHN has pros and cons. For short, fixed runs and device terminations, I prefer solid: it pushes better, holds shape in boxes, and lands securely under clamp-style receptacle and switch terminals. If you’re doing long pulls with multiple bends or working in tight, flexible conduit with lots of motion, stranded would be more forgiving. For a 25-foot kit, solid is the right call.

Installation experience

I used the tri-wire for two tasks: a short EMT run across a garage wall feeding a 20A GFCI circuit, and a simple stub-up in rigid to a weatherproof box. In both cases, the bundle pulled smoothly. Because the conductors are pre-twisted, I could tape on a pulling head once and go, rather than staging three separate leaders and hoping they don’t braid themselves. The twist also helps reduce snagging on couplings because the bundle tends to track as one body instead of letting a single conductor nose into a thread crest.

A few notes from the pull:
- I deburred every cut and reamed the conduit. The nylon jacket is tough, but sharp edges win that battle.
- I used a dab of wire lube at the first coupling. Not strictly necessary on short, straight runs, but it keeps things civilized around the second 90.
- The coil has a bit of memory. I hung the bundle from a rafter for a minute and reverse-twisted by hand to relax it before the pull. That knocked down the springiness and made pay-out predictable.
- I left 16–18 inches of extra slack in each box. Solid wire doesn’t like being reworked repeatedly; give yourself enough to land once and leave a service loop.

Terminations were straightforward. The solid conductors lay flat under clamp plates and hold shape as I dress the box. Strip length was consistent, and the copper was clean and untinned—ideal for standard terminations.

Performance and code considerations

As a 12 AWG copper THHN, the expected use is a 20A branch circuit at 600V or less in a raceway. Color coding is what you want: black for hot, white for neutral, green for equipment ground. This is not a “12/3 with red” set—there’s no second hot. If you’re running a multi-wire branch circuit or feeding a 240V load with a neutral, you’ll need an additional red conductor pulled alongside or a different bundle entirely.

One important note about locations: THHN as labeled is a dry-location insulation. Many modern THHN conductors are dual-rated THHN/THWN or THHN/THWN-2 and can be used in wet locations (including most outdoor conduit). Before you assume outdoor suitability, check the conductor printing on the jacket you’re using; don’t rely solely on a product description. If yours is THHN-only, keep it to dry spaces or choose dual-rated conductors for any raceway that qualifies as wet.

Conduit fill and bend count are unchanged versus pulling loose singles, since you are still dealing with three individual conductors. The twist adds a touch of friction, but on a 25-foot run with a couple of 90s, that’s marginal. If you’re approaching the limits of a long pull, you’re outside this product’s intended sweet spot anyway.

Where it fits

• Short branch-circuit runs in garages, basements, and utility spaces.
• Stubbing up to weatherproof boxes (with dual-rated conductors, as applicable).
• Quick additions where you need one hot, one neutral, and a ground in a tidy bundle.
• Upgrades where buying three 100-foot spools would be overkill.

For service work and small projects, the 25-foot length is practical. I didn’t end up with a mountain of leftover color I’ll never use, and the kit is easy to store in a bin.

Limitations and wish list

• No red conductor. If your workflow often includes multi-wire branch circuits, you’ll want a set that substitutes red for green plus a separate ground, or a four-conductor bundle.
• Solid only. Perfect for short, fixed runs; less ideal for long pulls with tight radii or frequent motion. A stranded version would be nice for flexible conduit-heavy jobs.
• Labeling and guidance. The coil I used came with minimal documentation. Markings on the conductors are the definitive source; still, a small card clarifying ratings, typical applications, and wet/dry guidance would help DIYers avoid mistakes.

Tips for best results

• Deburr and ream every conduit end. The nylon jacket will thank you.
• Pre-straighten the first few feet and relax the coil memory before pulling.
• Use a proper pull head or staggered tape wrap—don’t just glob tape around the bundle.
• A tiny amount of wire lubricant reduces friction on bends, especially in longer or older conduit.
• Leave a generous service loop in each box; solid conductors are less forgiving of repeated re-terminations.
• Verify insulation markings for wet/dry rating before using outdoors or underground-in-conduit.

Value

For small jobs, the value proposition is strong. The price of three short, color-correct conductors bundled for one pull compares favorably with piecemeal purchases, and it saves time. The real savings is in setup and pull efficiency: fewer leaders to fuss with, less chance of color mismatches, and a cleaner result in the box.

Verdict

Southwire’s 12/3 THHN tri-wire is a smart, time-saving solution for short conduit runs where you need a hot, neutral, and equipment ground. The solid copper conductors strip cleanly, land securely, and the factory twist makes pulling simple and organized. It hits the sweet spot for service calls and small projects where buying three large spools doesn’t make sense.

I recommend it for electricians and capable DIYers who do occasional branch-circuit work in raceways. It’s fast, tidy, and appropriately spec’d for 20A circuits in dry locations (or wet, if your specific conductors are dual-rated—verify the printing). If you often need a second hot or prefer stranded for long, complex pulls, this isn’t your one-size-fits-all solution. But for the majority of short, straightforward runs, it’s exactly the right tool for the job.