Wire and Magnet Wire for Repairs

Section Overview

The last consumable of this chapter is the humble wire — and in repair, it does a lot: it jumpers two points, bridges a broken trace, carries a modification, and — in its finest form — rebuilds connections too small to see clearly. There are a few families. Hook-up wire is the everyday insulated copper wire — solid or stranded — for general connections and jumpers. Magnet wire (also called enameled wire) is solid copper coated with a thin insulating enamel (a varnish, not a plastic jacket); it's what coils, inductors, transformers, and motors are wound from, and in repair it's prized for very fine jumpers and broken-trace repairs because it's so thin. And there's specialty fine wire — Kynar (wire-wrap) wire — for the most delicate trace work. Choosing wire runs on three properties. Gauge (AWG) is its thickness — with the counter-intuitive rule that a larger AWG number means a thinner wire — chosen for how much current it carries (too thin overheats) and how it fits. Solid versus stranded decides flex: solid holds its shape but breaks if repeatedly bent, while stranded is flexible. And the insulation decides heat tolerance — PVC melts back from the iron, but PTFE (Teflon) resists it, which is why PTFE is the repair favorite. One defining gotcha runs through magnet wire: its enamel is an insulator, so you must scrape or burn it off the end before solder will stick. Master the strip-without-nicking and tin-the-strands habits, and a spool of the right wire lets you stitch almost any repair back together. This section closes Chapter 10 — and Volume 2.

Why This Matters

Wire is where a lot of repairs live or die. A lifted or broken trace — one of the most common board injuries — is fixed with a wire jumper, and choosing and preparing that wire correctly is the whole repair. Get it wrong and the consequences are real. Use a wire too thin (too high an AWG) for a power circuit and it overheats — a genuine fire risk, not just a nuisance. Use solid wire where the repair flexes and it work-hardens and snaps, creating an intermittent fault that's maddening to find. Use cheap PVC-insulated wire right next to your soldering and the iron melts the insulation back, exposing conductor and risking shorts. Reach for magnet wire for a fine-pitch jumper — exactly the right choice — but forget that its enamel must be removed, and you'll chase a "cold joint" that won't take solder for ten frustrating minutes before realizing the solder never touched copper. Nick the conductor while stripping and you've weakened the wire at precisely the point it will later break. Each of these is a specific, avoidable failure that this section's knowledge prevents. And the fine-wire skills here — magnet and Kynar wire for trace repair — are the foundation of board-level repair you'll build on for the rest of the handbook. Choosing the right wire, in the right gauge and insulation, and preparing it correctly, is a core repair craft — the difference between a jumper that lasts and one that overheats, breaks, or never solders at all.

Required Prerequisites

Soldering Iron Selection — Beginner to Professional — repair wire is attached with a soldering iron, and much of choosing wire (especially the insulation's heat resistance and burning magnet-wire enamel off) is about the iron's heat. Know your heat source first.

Recommended Consumables

Hook-up wire in a few gauges — a thinner gauge (around twenty-six to thirty AWG) for signal jumpers and fine work, a heavier gauge for power; both solid and stranded
Magnet wire (enameled, a fine gauge such as thirty AWG or thinner) for fine trace and jumper repairs
Kynar / wire-wrap wire for the most delicate trace repair
PTFE (Teflon)-insulated wire for repairs near soldering (its insulation won't melt back)
Wire strippers sized to the gauges you use, flush cutters, and tweezers
Flux and solder (Sections 10.1, 10.2) — for tinning and for burning magnet-wire enamel off

Recommended Practice Hardware

A scrap board with traces to practice cutting and jumpering a broken trace
Hook-up wire (solid and stranded), magnet wire, strippers, flux, and a soldering iron (Chapter 5)
A magnifier or microscope (Chapter 9) for fine magnet-wire work
Fume extraction or ventilation (Chapter 1) — for the flux and enamel-burning fumes

Real-World Applications

Repair wire shows up the moment a board is injured. A technician who lifts a pad and trace while desoldering bridges the break with a thin jumper wire, scraping to bare copper at each end and soldering across the gap — restoring the broken connection. Someone performing a manufacturer's board modification (a "bodge") runs a fine wire between two points per the service bulletin. A repairer fixing a hair-fine broken trace under a microscope reaches for magnet wire — so thin it follows the original trace — and burns the enamel off the tips with iron and flux so the solder takes. A tech rebuilding a small inductor or motor winding re-winds it with fresh magnet wire of the correct gauge. And throughout, the pros make choices that prevent failures: stranded wire where a repaired cable flexes (so it won't snap); a gauge heavy enough for a power rail (so it won't overheat); PTFE-insulated wire near hot soldering (so the insulation won't melt); and careful stripping that never nicks the conductor (so the wire won't break later). The failures this prevents are the insidious ones: an intermittent fault from a solid wire that cracked at a flex point; an overheating jumper from undersized wire; a short from melted insulation; and the classic beginner time-sink — magnet wire that "won't solder" because the enamel is still on. The right wire, well chosen and well prepared, is what turns a damaged board back into a working one.

Common Challenges

Magnet wire won't take solder. Its enamel is an insulator — you must scrape or burn it off the end (heat and flux) so solder can wet the bare copper. This is the classic magnet-wire surprise.
A solid-wire jumper keeps breaking. Solid wire work-hardens and snaps where it flexes — use stranded wire for anything that moves.
The insulation melted back while soldering. PVC insulation shrinks from the iron's heat — use PTFE (Teflon)-insulated wire for work near soldering.

Safety Notes

Risk Level: Low. Working with wire is low-risk — but an undersized wire is a genuine fire hazard, and stripping and enamel-burning have their own cautions, so the callout is real.

Match the gauge to the current — an undersized wire overheats — and strip without nicking

An undersized wire overheats and is a fire risk. A wire that is too thin (too high an AWG number) for the current it carries has too much resistance for that current and heats up — on a power circuit, a badly undersized jumper can get hot enough to melt insulation or start a fire. Match the gauge to the current, and err heavier on power rails; fine gauges are for low-current signal and trace repair, not for power. Strip insulation without nicking the conductor: a nick removes copper and creates a weak point where the wire will later break — an intermittent fault that's hard to diagnose — so use strippers sized to the gauge and pull straight. Burning magnet-wire enamel off produces fumes (the enamel and flux vaporize), and melting PVC insulation gives off fumes too, so ventilate (the flux-fume rule from Sections 10.2 and 10.3 applies). The iron is hot, as always. And mains-voltage wiring is a different matter — it has its own insulation, rating, and safety requirements, and any powered/mains work is governed by Sections 3.1 and 3.2. None of this makes wire work dangerous — with the right gauge for the current, clean stripping, and ventilation — but the undersized-wire fire risk is the one to respect.

Professional Tips Before Starting

Match the gauge to the current, and keep a few on hand. A larger AWG number is thinner and carries less current — use fine gauges for signal and trace repair, heavier for power. Undersized wire overheats.
Solid for fixed, stranded for flexing. Solid wire holds its shape (great for PCB jumpers) but breaks when repeatedly bent; stranded is flexible for anything that moves — and tin its end to bind the strands before soldering.
Remember the enamel on magnet wire. Magnet wire looks like bare copper but is enamel-coated — it won't solder until you scrape or burn the enamel off. And favor PTFE-insulated wire near the iron so the insulation won't melt back.

Wire for Repair — Types, Gauge, Insulation, and Magnet Wire

The Wire Families

Repair uses a few distinct kinds of wire. Hook-up wire is the general-purpose insulated copper wire you reach for most: a copper conductor (solid or stranded) inside a plastic insulating jacket, used for jumpers, connections, and wiring of all kinds. Magnet wire — also called enameled wire — is different: it's solid copper coated with a very thin layer of insulating enamel (a baked-on varnish) rather than a thick plastic jacket. That thin coating is why it's called "magnet" wire — it lets many turns pack tightly to wind coils, inductors, transformers, and motor windings — and it's why, in repair, it's ideal for the finest jumpers and broken-trace fixes: it's hair-thin and follows tight paths. Finally, specialty fine wires like Kynar (wire-wrap) wire — very thin, with a tough thin insulation — are used for delicate trace repair and bodges. Hook-up wire for general work; magnet wire for fine, coil, and trace work; Kynar for the most delicate repairs.

Gauge (AWG)

A wire's thickness is its gauge, given in AWG (American Wire Gauge). The rule that trips up every beginner: a larger AWG number means a thinner wire — thirty AWG is much thinner than twenty AWG, which is thinner than twelve AWG. (This is covered in the wire-tools section — the number counts how many "draws" through the die, so more draws equals thinner.) Gauge matters for two reasons. First, current capacity: a thicker wire (lower AWG) carries more current; a wire too thin for its current overheats (the Safety Notes' fire risk). So you match gauge to current — fine gauges for low-current signal and trace repair, heavier gauges for power. Second, physical fit: fine-pitch trace repair needs a very thin wire (fine AWG or magnet wire), while a power jumper wants something sturdier. Pick the gauge by the current it must carry and the space it must fit — and remember bigger number, thinner wire.

Solid vs Stranded

Hook-up wire comes as solid or stranded, and the choice is about flexing. Solid wire is a single, solid conductor: it holds its shape (you can route and bend it to stay put), which makes it great for PCB jumpers, breadboarding, and wire-wrap — but it work-hardens when bent repeatedly and eventually snaps, so it's poor for anything that moves. Stranded wire is many fine strands twisted together: it's flexible and survives repeated flexing, which makes it right for anything that moves or vibrates (cables, leads, anything that isn't rigidly fixed). Stranded wire's one handling note: the loose strands should be tinned — twisted and coated with a little solder — to bind them into a solid tip before you insert or solder them, or they fray and splay. Solid for fixed, shape-holding jumpers; stranded for anything that flexes — and tin stranded ends before soldering.

Insulation and Heat Resistance

The insulation over hook-up wire varies, and for repair the key property is heat resistance — because you solder near it. PVC is the common, cheap insulation, but it's heat-sensitive: the soldering iron's heat makes it shrink and melt back, exposing conductor near your joints. PTFE (Teflon) insulation is heat-resistant — it does not melt or shrink from the iron — which is exactly why it's the favorite for repair wiring: you can solder right up to it without it retreating. Silicone insulation is very flexible and handles high temperatures well (good for heat and tight bends). And Kynar is a thin, tough insulation used on fine wire-wrap and trace-repair wire. For repair work near the iron, choose PTFE (Teflon) so the insulation won't melt back; PVC is fine away from heat, silicone for flex-and-heat.

Magnet Wire and Stripping the Enamel

Magnet wire deserves its own attention because of one defining property: its insulation is a thin enamel that looks like nothing — the wire appears to be bare copper — but is a real electrical insulator. The consequence: you cannot solder magnet wire until you remove the enamel from the part you're soldering. If you try to solder the enamel-coated wire directly, the solder simply will not stick — it beads and rolls off, exactly like soldering an oxidized surface with no flux — and beginners waste time thinking they have a "cold joint" when in fact the solder never reached copper. There are two ways to remove it: scrape it off mechanically (a knife, fine sandpaper, or an abrasive) to expose bright copper; or burn it off with the iron — hold the tinned iron and a little flux/solder on the wire end, and the heat and flux decompose and clear the enamel so the solder can wet the copper. (The burn-off method works well on common solderable enamels; some tough high-temperature enamels — polyimide and the like — resist burning and must be scraped instead.) Once the enamel is off and the tip is tinned, magnet wire solders like any copper. The rule that saves the frustration: magnet wire is enamel-coated — scrape or burn the enamel off the end, or it will never solder.

Repair Uses and the Strip/Tin Workflow

Pulling it together, here's how wire serves a repair. The most common use is the jumper wire — a length of wire soldered to bridge two points, especially to repair a broken or lifted trace (you solder the wire across the break, restoring the connection) or to carry a modification (a bodge/mod wire). Fine trace repair uses magnet or Kynar wire for its thinness. Coil and transformer repair uses magnet wire to rewind. The preparation workflow is always the same shape: (1) Choose the wire (gauge to current/fit, solid/stranded to flex, insulation to heat). (2) Strip the insulation without nicking the conductor — a nick weakens the wire and it breaks there later — using strippers sized to the gauge. (3) Prepare the end: tin stranded ends to bind the strands; scrape or burn the enamel off magnet wire. (4) Solder the prepared end to the board (with flux, as always). (5) Secure the wire if needed (a dab of adhesive — Section 10.5 — for strain relief). Choose, strip cleanly, prepare the end, solder, and secure — that workflow wires almost any repair.

Common Mistakes

Trying to solder magnet wire with the enamel on. It won't stick — scrape or burn the enamel off the end first.
Using undersized wire for the current. Too thin (too high AWG) overheats — match gauge to current, heavier for power.
Using solid wire where it flexes. Solid wire snaps at flex points — use stranded for anything that moves.
Nicking the conductor while stripping. A nick weakens the wire and it breaks there later — use gauge-matched strippers and pull straight.
Using PVC-insulated wire right at the iron. PVC melts back — use PTFE (Teflon) for work near soldering.
Not tinning stranded ends. Loose strands fray and splay — tin the end to bind them before soldering.

Troubleshooting Guidance

Most wire problems are the wrong type, bad preparation, or the magnet-wire enamel. If solder won't stick to a "bare copper" wire: it's magnet wire with enamel still on — scrape or burn the enamel off and tin the copper. If a jumper overheats or gets warm in use: the wire is undersized for the current — replace it with a heavier (lower-AWG) gauge. If a repaired connection keeps going intermittent: a solid wire cracked at a flex point, or the conductor was nicked while stripping — use stranded wire for flexing joints and strip without nicking. If the insulation melted back while you soldered: it's PVC — switch to PTFE (Teflon) for work near the iron, and trim back the damaged insulation. If stranded wire frays and won't go into a hole or pad: you didn't tin the end — twist and tin it first. If a fine magnet-wire trace repair keeps lifting or breaking: the wire may be too fine to handle the mechanical stress, or it needs securing — choose an appropriate gauge and secure it with a dab of adhesive (Section 10.5). And if you're unsure of a wire's gauge or current rating for a power circuit: err heavier, and remember mains wiring has its own requirements (Sections 3.1/3.2). The throughline: right type and gauge, clean stripping, tinned or de-enameled ends, and PTFE near the iron.

Verification & Testing Methods

Use this as a wire-selection-and-preparation checklist:

[ ] I've chosen the wire family for the job — hook-up wire for general jumpers, magnet wire or Kynar for fine trace repair.
[ ] The gauge suits the current (heavier for power; a larger AWG number is thinner) and the physical fit.
[ ] I've chosen solid (fixed, shape-holding) or stranded (flexing) correctly, and I tin stranded ends before soldering.
[ ] The insulation suits the heat — PTFE (Teflon) for work near the iron, so it won't melt back.
[ ] For magnet wire, I scrape or burn the enamel off the end before soldering.
[ ] I strip without nicking the conductor, and I've considered strain relief (adhesive, Section 10.5) and the undersized-wire fire risk.

Then try the practice exercises below — wire-selection reasoning; scenarios differ from the quiz.

Practice Exercises

Choose the wire (5 minutes, reasoning). For (a) a power-rail jumper carrying significant current, (b) a repair on a cable that will flex in use, and (c) a hair-fine broken-trace repair under a microscope, name the wire type, gauge sense (heavier or finer), and solid-or-stranded you'd choose, and why.
The magnet-wire gotcha (5 minutes, reasoning). Explain why solder will not stick to magnet wire as-is, and describe the two ways to fix it — relating it to why flux and a clean copper surface matter for wetting.
Diagnose the intermittent jumper (5 minutes, reasoning). A repaired connection keeps going intermittent at a spot that flexes. Give the two most likely wire-related causes and how you'd prevent each.
Gauge and safety (5 minutes, applied). Explain the AWG rule (which way is thinner), why an undersized wire on a power circuit is a fire risk, and how you'd choose a safe gauge.

These core ideas — the wire families, gauge (AWG) and current, solid versus stranded, insulation and heat resistance, and magnet wire's enamel — are tested in the Chapter Quiz at the end of this chapter, where a score of 80% is required to continue.

Key Takeaways

Repair wire comes in families: hook-up wire (insulated, general jumpers and connections), magnet wire (thin enameled copper for coils and fine trace/jumper repair), and specialty Kynar/wire-wrap wire (delicate trace repair).
Gauge is AWG — a larger number is a thinner wire — chosen for current (too thin overheats, a fire risk) and fit: fine gauges for signal/trace, heavier for power.
Wire is solid (holds shape for fixed jumpers but breaks when flexed) or stranded (flexible for anything that moves — and tin the end before soldering).
Insulation sets heat resistance: PVC melts back from the iron, but PTFE (Teflon) resists it — the repair favorite for work near soldering; silicone for flex-and-heat.
Magnet wire's enamel is an insulator — you must scrape or burn it off the end before solder will stick (the classic magnet-wire surprise).
Prepare wire correctly: strip without nicking the conductor (a nick breaks later), tin stranded ends, de-enamel magnet wire, then solder — and a jumper wire bridges a broken/lifted trace or carries a modification.

Skills Learned

You can now identify the wire families and choose the right one for a repair.
You can now choose a gauge for current and fit, knowing a larger AWG number is thinner.
You can now choose solid versus stranded wire by whether it will flex.
You can now choose insulation by heat exposure, favoring PTFE near the iron.
You can now prepare wire — strip without nicking, tin strands, and remove magnet-wire enamel.

Glossary Additions

hook-up wire — general-purpose insulated copper wire (a conductor inside a plastic insulating jacket, available solid or stranded and in a range of gauges) used for the everyday connections, jumpers, and wiring of electronics repair; it is chosen by gauge (for current and fit), by solid-versus-stranded construction (for whether it must flex), and by insulation type (for heat resistance, with PTFE favored for work near soldering).
magnet wire — solid copper wire coated with a thin baked-on layer of insulating enamel (varnish) rather than a thick plastic jacket, used to wind coils, inductors, transformers, and motors, and in repair for the finest jumpers and broken-trace fixes because it is so thin; because the enamel is an electrical insulator, the enamel must be scraped or burned off the end (with heat and flux) before the wire will accept solder. Also called enameled wire.
stranded wire — wire whose conductor is made of many fine strands twisted together rather than a single solid conductor, giving it flexibility that survives repeated bending, which makes it the right choice for connections that move or vibrate; its loose strands should be tinned (twisted and coated with a little solder) to bind them into a solid tip before insertion or soldering, unlike solid wire, which holds its shape but work-hardens and breaks when flexed repeatedly.
jumper wire — a length of wire soldered across two points to make or restore a connection, most often to bridge a broken or lifted printed-circuit trace or to carry a board modification (a bodge or mod wire); fine trace-repair jumpers use very thin hook-up, magnet, or Kynar wire, and the jumper's ends are prepared (stripped without nicking, tinned, or de-enameled) before being soldered in place.

Suggested Next Sections

Must read next:

What Is Soldering? — this section closes Chapter 10 and completes Volume 2, "The Electronics Lab." Volume 3, "Soldering and Rework Fundamentals," opens by turning from the tools and materials to the craft itself: what soldering actually is, at the level of heat, metal, and a sound joint.

Recommended:

Soldering Iron Selection — Beginner to Professional — the iron you attach repair wire with, whose heat drives the insulation choice and burns magnet-wire enamel off.
Solder Selection — Alloys and Form Factors — the solder that joins the wire, and the tinning that binds stranded ends and wets de-enameled magnet wire.