Ferrule, Spade or Lug: Choosing a Crimp Terminal for Stranded Wire
Three kinds of crimp terminal cover almost every stranded wire in a panel, a car or a battery box. The wire gauge picks the size. The thing it connects to picks the kind.
Why stranded wire needs an end at all
Solid wire goes into a screw terminal as it is. Stranded wire is different. It is dozens of thin copper threads twisted together, and when a screw clamps down on them, some spread sideways, some fold back and a few end up outside the clamp.
The joint may work on the day you make it. The trouble comes later, when the panel vibrates, the wire warms and cools a few hundred times, or someone retightens the screw. Loose strands mean a smaller contact area, and a smaller contact area runs hot.
A crimp terminal turns the loose end into one solid piece of metal. What kind of piece depends on where the wire is going.
- Ferrules
Non-Insulated Wire Ferrules
Bare tin-plated copper ferrules, no collar, from 24 AWG to 6 AWG.$7.99 to $9.99per pack, by sizefrom $0.008 per piece
What the workplace rule asks of a terminal
OSHA's electrical rules for workplaces put the goal in one sentence. It is worth reading slowly, because every crimp terminal we sell is one of the devices it names.
Connection of conductors to terminal parts shall ensure a good connection without damaging the conductors and shall be made by means of pressure connectors (including set-screw type), solder lugs, or splices to flexible leads.
U.S. Occupational Safety and Health Administration, 29 CFR 1910.303, General requirements (electrical, workplaces). Read 28 September 2026.
A crimped ferrule, spade or lug is a pressure connector. It makes the connection by squeezing metal around the wire. The same sentence also sets the bar: a good connection, made without damaging the conductor. A crimp made with the wrong tool, or on the wrong size of wire, fails both halves.
That rule covers workplaces. At home nobody inspects your terminal block, but the physics is the same.
- Ferrules
18 AWG Insulated Wire Ferrules
Tin-plated copper sleeve with a nylon collar for 18 AWG stranded wire.$7.99per pack, by sizefrom $0.008 per piece
Ferrules: stranded wire into a terminal block
A ferrule is a short tube of tin-plated copper, often with a plastic collar. You slide it over the stripped wire and crimp it. The terminal then clamps one round pin instead of loose strands.
Ferrules are the right answer wherever stranded wire goes into a screw clamp or a push-in spring clamp: DIN-rail terminal blocks, relays, power supplies, motor drives, 3D printer boards.
Size them by the wire, never by the terminal. An 18 AWG wire takes an 18 AWG ferrule. The table below covers every gauge in our range, worked out from the current packs.
| Wire | Metric size | Collar colors | Pack sizes | Insulated, per piece | Bare, per piece |
|---|---|---|---|---|---|
| 24 AWG | 0.34 mm² | Black, Blue, Red, White | 1000 pcs | $0.010 | $0.010 |
| 22 AWG | 0.5 mm² | Black, Blue, Green, Red, White, Yellow | 1000 pcs | $0.009 | $0.009 |
| 20 AWG | 0.75 mm² | Black, Blue, Green, Grey, Red, White, Yellow | 1000 pcs | $0.008 | $0.008 |
| 18 AWG | 1.0 mm² | Black, Blue, Green, Red, White, Yellow | 1000 pcs | $0.008 | $0.008 |
| 16 AWG | 1.5 mm² | Black, Blue, Green, Red, White, Yellow | 1000 pcs | $0.010 | $0.010 |
| 14 AWG | 2.5 mm² | Black, Blue, Green, Red, White, Yellow | 1000 pcs | $0.010 | $0.010 |
| 12 AWG | 4.0 mm² | Black, Blue, Grey, Red, White | 500 pcs | $0.020 | $0.020 |
| 10 AWG | 6.0 mm² | Black, Blue, Red, White | 200 pcs | $0.050 | $0.049 |
| 8 AWG | 10 mm² | Black, Blue, Red, White | 200 pcs | $0.040 | $0.040 |
| 6 AWG | 16 mm² | Black, Blue, Red, White | 200 pcs | $0.040 | $0.040 |
Spade terminals: a joint you will open again
A spade terminal, or quick disconnect, ends the wire in a flat tab or a socket for one. It is for connections that come apart: a switch on a lamp, the leads of a trailer light, a fan you will replace.
The insulation color tells the wire range. Red takes 22 to 16 AWG, blue 16 to 14, yellow 12 to 10. A fully insulated female spade covers the whole socket, so a loose one cannot touch the terminal next to it.
Spades are not sealed. Under a hood or outdoors, finish the joint with glue-lined heat shrink.
- Ferrules
16 AWG Insulated Wire Ferrules
Tin-plated copper sleeve with a nylon collar for 16 AWG stranded wire.$9.99per pack, by sizefrom $0.010 per piece
Ring lugs: bolting a heavy cable down
A ring lug ends a cable in a flat ring that goes over a stud and under a nut. Battery posts, bus bars, starter motors and inverters all take ring lugs. A spade would work loose there and a ferrule is far too small.
Two numbers choose the lug: the cable gauge and the stud diameter. A 4 AWG cable on a 3/8 in battery stud needs a 4 AWG lug with a 3/8 in ring. Measure the stud before you buy. The ring cannot be drilled out safely.
On boats, the federal rule starts even earlier, with the wire itself.
Each conductor must be insulated, stranded copper.
U.S. Coast Guard, Code of Federal Regulations, 33 CFR 183.425, Conductors: General (boat electrical systems). Read 28 September 2026.
Solid wire cracks when it vibrates, and a boat vibrates all the time. Stranded wire, crimped into a lug, is the combination the rule has in mind.
- Ferrules
22 AWG Insulated Wire Ferrules
Tin-plated copper sleeve with a nylon collar for 22 AWG stranded wire.$8.99per pack, by sizefrom $0.009 per piece
The tool matters as much as the terminal
Each terminal has its own crimper. A ferrule crimper squeezes the tube into a square or a hexagon. A spade crimper has shaped jaws that roll the barrel without cutting the nylon. A lug crimper is a heavy tool, often a hammer or a hydraulic press, sized to the cable.
Pliers flatten a barrel into an oval that looks closed and pulls off. If you do not have the tool, buy it before the terminals. Our ferrule kit comes with one.
- Strip to the length of the metal barrel, no longer.
- Push the wire in until the copper shows at the far end of a ferrule.
- Crimp once, in the middle of the barrel.
- Pull the wire firmly. If it moves, cut it off and start again.
What we cannot tell you
We do not know your terminal block or your cable's current. Ampacity, fuse size and wire gauge for a circuit are for the equipment maker's manual or an electrician, and our range is only the end of the wire.
