What Type of Copper Wire Do You Have?

Nearly every manufactured wire carries its identity in ink: type letters like THHN, NM-B, CAT5E, or RG-6, a gauge like 12 AWG, and a voltage rating. Even a partial print narrows the field enormously — “12 AWG” plus a flat sheath means you are almost certainly holding Romex-style building cable. Wipe off dust, look along the first few feet, and photograph the clearest section. Our wire-marking decoder walks through every part of the print string.

One — solid or stranded? Look at a cut end. One solid rod of copper is typical of building wire; many fine strands mean flexible cable or cord. Two — the magnet test. If a magnet grabs the conductor, there is steel in it — common in coax center conductors (copper-clad steel) and armored cable. Three — cut and scrape. A fresh cut shows the truth: solid copper all the way through, a silver-white core (copper-clad aluminum), or a silver surface over copper (tinned). These three tests identify nine wires out of ten.

Once you know the construction, the family is usually obvious:

• Single insulated conductors, often in conduit — building wire like THHN. Building wire guide →
• Flat or round sheathed cable with 2–3 conductors — Romex-style residential cable. Building wire guide →
• Thin multi-pair cable, often blue or gray — telephone or network wire. Communications wire guide →
• Round cable with layered construction — coaxial cable. Coax guide →
• Very flexible, thick rubber jacket — welding, battery, or DLO cable. Heavy flexible cable guide →
• Metal spiral armor around the conductors — MC/BX armored cable. Armored cable guide →

Copper-colored is not always solid copper. Copper-clad aluminum (CCA), copper-clad steel, tinned copper, and plain aluminum all fool sellers — and each grades differently. Run the cut, scrape, and magnet tests before you assume. Our look-alike guide covers all four with photos of what each cut end looks like. Honest identification is what protects your price: the right grade from the start means the right offer.

Photograph what you have — the wire, any jacket markings, and the overall quantity — and send it to Ironcrest for today’s offer. We buy nationally and coordinate pickup from your site.

Sell your copper to Ironcrest →  |  Call or text 312-880-8174  |  Send photos →

See also: How to read wire markings & AWG sizes  |  Solid copper vs. look-alikes  |  Copper wire grades guide (canonical)

How can I tell what kind of wire I have if the jacket has no markings?

Work the three tests: solid vs. stranded at a cut end, a magnet for steel content, and a fresh cut or scrape to see whether the metal is copper all the way through. Then match the construction to a wire family using the guide above — or photograph the cut end and the coil and send it to a buyer. A buyer identifies mystery wire as a matter of course.

Is all copper-colored wire actually copper?

No. Copper-clad aluminum has a copper-colored skin over a silver aluminum core; copper-clad steel hides steel under copper; tinned copper is silver on the surface with copper underneath; and plain aluminum wire is simply silver. A fresh cut end tells the truth every time.

Does the wire gauge tell me the type?

Partly. Gauge plus construction narrows it fast — 24 AWG twisted pairs are network or phone wire, 12 AWG singles are building wire, 4/0 fine-stranded is heavy flexible cable. But gauge alone never settles it; read the jacket print too.

What is the difference between solid and stranded copper wire?

Solid wire is one rod of copper — typical of building wire in walls and conduit. Stranded wire is many smaller strands twisted together — typical of flexible cable, cords, and large feeders. Both are valuable copper; the construction tells you the wire family, not the worth.

I found an unlabeled coil at a cleanout — what should I do?

Don’t strip it blindly and don’t guess. Photograph any markings (even partial), a fresh cut end, and the overall quantity, and send the photos to a buyer. Mystery coils from cleanouts, demolitions, and plant closures are a normal part of our business.