How to Strip Copper Wire: Knife, Stripper, or Machine (and When Not To)

Every scrapper eventually faces the same bucket of wire and the same question: strip it, or sell it as-is? Stripping multiplies what your copper pays per pound — but only if your method is fast enough that you’re not working for pocket change. Here’s every way to do it, with honest speed numbers, and the decision math that should come first.

Before you strip anything: do the math

Stripping trades your time for the gap between the insulated (as-is) price and the bare copper price. That gap changes with the cable type — thick THHN gives up its copper easily and grades high; Christmas lights are nearly all insulation. Two minutes with the numbers saves an afternoon of regret:

• The Copper Wire Yield Calculator shows what the copper inside is worth versus selling the cable as-is.
• The Strip or Sell calculator adds your time at an hourly rate and gives you a verdict.

As a rule of thumb: cable at 65%+ recovery (romex and up) is usually worth stripping; data cable and cords usually aren’t by hand. Check your exact cable on the copper-by-cable-type pages.

Method 1: Utility knife (free, slow)

The starter method: score the insulation lengthwise and peel the conductor out.

1. Anchor one end — step on it, clamp it, or pin it under a board.
2. Draw the blade along the wire, angled shallow so you ride the copper without nicking it.
3. Open the score with your thumbs and peel the insulation away in one run.

It works on anything, costs nothing, and is miserably slow: realistically 10–20 lb of cable per hour, less on thin or stranded wire. Fine for a one-time bucket of thick romex; a dead end for volume. A box cutter with a fresh blade beats a dull pocket knife by more than you’d think, and solid-core (romex) strips far better by hand than stranded cord — stranded conductors love to slice.

Method 2: Handheld wire stripper (~$20–60, better)

A small hand tool — a slot with an adjustable blade you pull the wire through. Some clamp to a bench; some chuck into a vise. This is the sweet spot for the occasional scrapper: 30–60 lb per hour on consistent, straight, mid-gauge wire, with far less blade risk to your hands. The catch: they hate irregular cable — flat romex jackets, kinked wire, and very thin gauges all fight the slot. If most of your wire is one consistent type, set the blade once and run it all.

Method 3: Drill-powered and benchtop machines (~$60–400, the volume answer)

A stripping machine is a hardened blade and a feed wheel — hand-cranked, drill-driven, or motorized. Feed the wire in; it comes out scored or fully split. Speeds of 100+ lb per hour are realistic once you’ve got a rhythm, and it makes previously “not worth it” cable (extension cords, thinner ICW) worth a second look because your labor per pound collapses.

The decision is pure math: a machine pays for itself when the extra money stripping earns you exceeds the machine’s cost. If stripping nets you an extra $1/lb of cable and the machine costs $200, that’s 200 lb of cable to break even — a weekend for a serious scrapper, a year for a hobbyist. Run your own numbers in the Strip or Sell calculator with machine-speed assumptions before buying.

Never burn wire. Ever.

The old-timer shortcut — burning insulation off in a barrel — is a hard no, for three compounding reasons:

1. It’s illegal almost everywhere: open burning of insulation releases dioxins and heavy-metal smoke, and fines run far past what the copper is worth.
2. Yards refuse or downgrade it. Burnt copper is obvious (blackened, brittle, annealed) and most reputable yards either turn it away or pay a punitive “burnt copper” grade below #2 — you lose money versus stripping.
3. It wrecks the copper. Heat oxidizes the surface, so even where it’s accepted, it never grades #1.

If stripping isn’t worth your time, the answer is to sell the wire as-is at the insulated price — never to burn it.

After stripping: protect your grade

Freshly stripped, shiny copper is bare bright — the top grade — but only if you keep it that way. Don’t nick it up, don’t leave chunks of insulation, keep tinned (silver-coated) strands in a separate pile, and store it dry. The difference between bare bright and #2 is real money on the same metal; see #1 vs #2 Copper for exactly where yards draw the lines.

Keep learning

• Know what’s inside before you start: copper content by cable type and the Master Recovery Table.
• Identify mystery wire first with the Copper Wire Identification Guide.
• Price the finished pile with the Copper Wire Yield Calculator.
• More in the Wire & Cable guides.