Stranded wire is an electrical conductor made of multiple thin metal strands bundled together, rather than a single solid piece of metal. Where solid wire is one continuous rod of copper or aluminum, stranded wire achieves the same total gauge by twisting together anywhere from 7 to over 100 individual strands. This construction makes the wire dramatically more flexible, which is why it shows up in everything from power cords to robotics.
How Stranded Wire Is Built
The basic idea is simple: instead of one thick copper rod, you bundle many thinner ones. A 22 AWG stranded wire, for example, might consist of 7 individual strands of 30 AWG wire twisted together. The combined cross-sectional area of all seven strands equals roughly the same conducting area as a single solid 22 AWG conductor.
Strand counts follow a pattern. The most common configurations use 7, 19, or 37 strands arranged concentrically, meaning each layer wraps around a central core strand. A 7-strand wire has one center strand surrounded by six. A 19-strand wire adds another ring of 12 around that. Higher strand counts like 49 or 65 use a “rope lay” construction, where small bundles are twisted together like a miniature cable.
There are eight official stranding classifications, labeled B through M. Class B is the most common and is the standard stranding for building wire. Classes C and D are considered “fine stranded” and often called welding cable because of their excellent flexibility. Classes G through M are the most finely stranded, using dozens or hundreds of hair-thin conductors, and are typical in robotics, drag chains, and other equipment that moves constantly.
Reading Stranded Wire Notation
Stranded wire specs are written as two numbers separated by a slash. The first number is the strand count, and the second is the gauge of each individual strand. So “7/30” means 7 strands of 30 AWG wire. That combination gives you an overall size equivalent to 22 AWG. The math follows a predictable shortcut: bundling 7 strands reduces the AWG number by 8 (so 7 strands of 38 AWG equals 30 AWG overall), 19 strands reduces it by 12, and 37 strands reduces it by 16.
Metric systems work similarly but reference cross-sectional area. A 1 mm² stranded conductor might be listed as “19/0.25 mm,” meaning 19 strands each 0.25 mm in diameter.
Why Stranded Wire Exists
Flexibility is the primary reason. A solid copper wire at larger gauges becomes stiff and difficult to route, and it will crack and break if bent back and forth repeatedly. Stranded wire handles three types of real-world stress that solid wire cannot: vibration over time, sharp bends during installation, and intentional flexing during use. Research into fatigue life has found a clear advantage with more, finer strands, though the improvement levels off at a certain point.
This makes stranded wire the standard choice for any application involving movement. Power cords, headphone cables, speaker wire, appliance wiring, automotive connections, computer peripheral cables, and musical instrument cables all use stranded conductors. In robotics and automated machinery, fine-stranded flex cable (Class 5 or 6) runs through drag chains that bend thousands of times without failure. Circuit board connections in tight spaces also favor stranded wire because it can twist and route around components.
How It Compares to Solid Wire
Solid wire wins on raw electrical performance. Because stranded wire has tiny air gaps between the strands, it carries slightly higher DC resistance than a solid conductor of the same gauge. Signal attenuation is 20 to 50 percent higher in stranded cables compared to solid copper, with the gap widening at smaller gauges (20 percent more attenuation at 24 AWG, 50 percent at 26 AWG). Solid wire also handles higher temperatures better, since the increased resistance in stranded conductors degrades performance more as things heat up.
Solid wire holds its shape, which is an advantage for permanent installations. It seats properly in push-in connectors on outlets, switches, and patch panels, and it stays put once terminated. It also resists corrosion better because there’s less exposed surface area. Cost is another factor: more strands mean more manufacturing steps, so stranded wire carries a price premium over solid at the same gauge.
Despite the electrical differences, both types carry the same official ampacity ratings. A 12 AWG stranded wire is rated for the same current as a 12 AWG solid wire, as long as the terminations are appropriate for the stranding class.
Where Each Type Gets Used
The split is straightforward. Solid wire goes inside walls, in structured cabling runs, and anywhere the wire gets installed once and never moves again. Residential wiring (Romex), Ethernet runs through ceilings, and thermostat wiring are all solid conductor territory.
Stranded wire goes everywhere else. Extension cords, appliance power cables, car wiring harnesses, patch cables between equipment, and any connection to something that moves or vibrates. AC power cords are stranded because they get coiled, bent, and dragged across floors. Automotive and aerospace wiring is stranded because engines and structures vibrate constantly. If the wire will ever flex during its lifetime, stranded is the right choice.
Terminating Stranded Wire
The one real downside of stranded wire is that it’s harder to connect reliably. Individual strands can splay apart when you strip the insulation, and shoving loose strands under a screw terminal creates uneven pressure, reduced contact area, and connections that loosen over time. This is the main failure mode for stranded wire installations.
Ferrules solve this problem cleanly. A ferrule is a small metal sleeve, usually tinned copper, that slides over the stripped end of a stranded wire. When crimped with a proper tool, it compresses the strands into a solid, compact tip that behaves like solid wire in a terminal. The crimp creates a gas-tight connection that resists vibration, thermal cycling, and strand splay. Modern spring-clamp and push-in terminals are often designed specifically for ferrule-tipped conductors.
Crimping is the preferred termination method overall. For larger connections, crimp lugs and ring terminals serve the same purpose as ferrules, containing the strands mechanically. One important rule: do not tin stranded wire with solder before inserting it into a screw terminal. Solder creeps under pressure over time, which loosens the connection and creates a potential hot spot. If you’re soldering stranded wire directly to a joint (like on a circuit board or splice), that’s fine, but solder is not a substitute for a proper crimp at a terminal.
A good ferrule crimp looks symmetrical with crisp, flat sides and no strands poking out. If you tug firmly on the wire, it should hold fast. Ratcheting ferrule crimpers that self-adjust across a range of sizes (typically 0.25 to 10 mm², or about 23 to 7 AWG) are the most practical tool for anyone doing regular panel or electrical work.