Bootlace Ferrules Explained: When to Use Them—and When Not To

You’ve stripped the flex, offered it up to the terminal and there’s always one strand that won’t play ball. A bootlace ferrule tidies things up—but a neat termination isn’t necessarily a good one.

The ferrule has to suit the conductor, the crimping tool and the terminal it’s going into. Get that combination right and it can make wiring and future maintenance easier. Get it wrong and you may be adding a problem rather than solving one.

So when should you use ferrules, when can you leave them out, and why does a red collar tell you less than you might think? Here’s what matters at the terminal.

By Gordon Routledge
Published: 10 May 2020 · Last updated: 12 September 2026

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Bootlace ferrule french and german colours — A box of colours, and more than one way to read them. Check the size before reaching for the crimping tool.

Why use ferrules?

A bootlace ferrule is a small sleeve fitted over the stripped end of a conductor and compressed with a suitable crimping tool. It keeps the fine strands together so they can enter a terminal as one prepared end. You’ll also see them described as wire-end ferrules, cord-end ferrules or cable end sleeves.

The important word is suitable. The conductor, ferrule, tool and terminal need to work together. A tidy-looking termination is only part of the job.

The Ultimate Guide To Ferrules

Watch on YouTube · Colour codes: 04:10 · Crimping tools: 09:20 · Conductor types: 14:32

Ferrules are particularly useful when preparing fine-stranded flexible conductors. They can help prevent individual strands escaping during insertion and make subsequent reconnection less fiddly.

That does not make them compulsory for every terminal. Some terminals accept fine-stranded conductors directly; others specify particular preparation. Check the equipment instructions for the conductor types, sizes and end treatments accepted.

Our video also examines why a ferrule is not an automatic improvement on a solid or coarsely stranded conductor. Start with the terminal’s requirements, rather than the assumption that every wire needs a sleeve.

ferrules safely capture individual strands of copper wire — Every strand has a job. Keeping them together makes the next connection easier to get right.

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Ferrule colour codes

Ferrule colour codes can be very confusing. There are two manufacturer led systems the French system, initially developed by Telemecanique (T), and the German system by Weidmuller (W). Both of these are in everyday use alongside an official German DIN standard.

VIDEO - Ferrule colour codes

Download a printable ferrule colour code

Ferrule colour-code table: 0.14–150 mm²

This table follows the eFIXX printable chart. Check the size on the packaging and identify its colour system before selecting a ferrule.

eFIXX ferrule colour codes

Size (mm²)	French — Telemecanique (T)	German — Weidmüller (W)	DIN colour column†
0.14	Brown	Grey	Grey*
0.25	Violet	Light blue	Yellow*
0.34	Pink	Turquoise	Turquoise*
0.5	White	Orange	White
0.75	Light blue	White	Grey
1.0	Red	Yellow	Red
1.5	Black	Red	Black
2.5	Grey	Blue	Blue
4.0	Orange	Grey	Grey
6.0	Green	Black	Yellow
10	Brown	Ivory	Red
16	Ivory	Green	Blue
25	Black	Brown	Yellow
35	Red	Beige	Red
50	Blue	Olive	Blue
70	—	—	Yellow*
95	—	—	Red*
120	—	—	Blue*
150	—	—	Yellow*

†This column reproduces the chart’s DIN 46228 column, including its marked exceptions. *The eFIXX chart marks these sizes as not included in the DIN standard. Their colours are reference information, not DIN-standard assignments. A dash means the chart does not specify a colour for that system and size.

Source: eFIXX Ferrule Colour Codes, 2025.

Notice how the colours repeat as sizes increase. A red collar alone cannot tell you which ferrule you have. These are colour-system comparisons, not permission to substitute one product for another.

Ferrule types

VIDEO - Ferrule types,tips and where to use them

Uninsulated ferrules

Without the plastic collar, uninsulated ferrules can suit locations where space is restricted. They still need to match the conductor and terminal; removing the collar does not remove the need to check compatibility.

Insulated ferrules have a plastic collar to help guide fine strands into the barrel, especially with smaller conductors. Choose the sleeve for the conductor and the available terminal space, rather than choosing by colour alone.

Sometimes the collar is the part you haven’t got room for.

Twin wire ferrules

Twin ferrules prepare two conductors together. Check that the terminal permits the intended arrangement and that its capacity covers the finished ferrule. Insulated twin ferrules have a wider collar to accommodate the two wires.

Two wires arriving at one terminal need a planned connection, not a squeeze-and-hope approach.

Match the ferrule’s specified conductor capacity to the wire you are preparing. For twin ferrules, check the stated capacity for each conductor. Do not judge the nominal conductor size solely by its apparent diameter: our newer video explains how conductor construction affects what you see before crimping.

The twin designation matters just as much as the colour.

Choosing the barrel length

Barrel length matters too. The prepared end needs to suit the depth and geometry of the terminal. Follow the specified strip length and preparation instructions; an unnecessarily long sleeve is not a shortcut to a better connection.

Choosing a ferrule crimping tool

A ferrule crimping tool forms the sleeve around the strands. Choose one specified for the ferrule type and size, including twin ferrules where relevant. Check the recommended tool and ferrule combination, particularly where an approved system is required.

Square, hexagonal and other profiles are available. The resulting shape must fit the intended terminal; the largest tool or most impressive-looking crimp is not automatically the best choice.

The newer video compares manual and powered options and explains why a tool that suits your everyday conductor sizes can make repeated work easier. It also looks at ferrule quality: products that look similar on the outside may not be equivalent underneath.

A practical preparation check

Confirm what the terminal accepts: conductor type, size and preparation.
Select the specified ferrule type, capacity and barrel length.
Strip to the required length without damaging or losing strands.
Insert the conductor fully and crimp using the specified tool and setting.
Inspect the prepared end for escaped strands, damaged insulation or an incomplete crimp.
Connect it in accordance with the equipment instructions, including any specified tightening torque.

The detailed dimensions and acceptance checks belong to the product instructions. A neat finish helps you inspect your work, but appearance alone does not prove a sound connection.