Wire ferrule sizes run from 0.14 mm² to 150 mm², covering signal wiring up to heavy power terminations. Match the ferrule to your conductor’s cross-section first. Color is a confirmation, not a starting point. Within the standardized range, the same gray collar appears on 0.75 mm² and 4.00 mm² ferrules under DIN 46228-4.
The same part is sold under four names. Wire ferrule is standard North American usage, bootlace ferrule is the common UK term, cable ferrule appears in both markets, and cord end terminal is how most manufacturers label them in their own catalogues. All four describe the same component: a metal sleeve crimped onto a stranded conductor. For consistency, wire ferrule is the term used throughout.
Wire Ferrule Sizes at a Glance
Wire ferrules are sized by conductor cross-section: mm² in metric systems, AWG in North American practice. For control panel work, the practical range is 0.5 mm² (20 AWG) to 6 mm² (10 AWG). Select by cross-section first, then confirm barrel length against your terminal’s strip length spec. Color coding under DIN 46228-4 is a visual aid only. Gray alone covers three different sizes.
Which unit you start from depends on where you work. North American panel shops look up ferrules by AWG; UK and European shops look up bootlace ferrule sizes by mm². Both routes land on the same part, so this guide gives you a table for each:
- Wire Ferrule Sizes by AWG: start from American wire gauge
- Complete Wire Ferrule Size Chart in mm²: start from metric cross-section, with the full DIN 46228-4 colour table
For a quick one-size lookup without scanning the full tables, use the AWG to mm² converter. It keeps calculated conductor area, common metric references and Termnex catalogue labels separate.
If your conductor is already marked in mm² and you just need the verified colour and dimensions, use the Wire Ferrule Size & Colour Code Chart.
If you’re new to wire ferrules and want a grounding in how they work and where they’re used, start with What Are Wire Ferrules? A Panel Builder’s Guide to Types, Sizes and Selection.
Wire Ferrule Sizes by AWG
If you specify wire in AWG, work from this table. One thing to know before you order: the ferrule itself is normally marked in mm², not AWG, because the part is manufactured to a metric standard. A bin labelled 2.5 is the ferrule you want for 14 AWG wire. There is no separate “14 AWG ferrule” part number in most catalogues.
The table separates mathematical conductor area from nominal ferrule catalogue references. Those values are not interchangeable. A catalogue may group the same AWG under more than one metric ferrule size, and a supplier’s packaging may use a different AWG label again. Select by the conductor’s marked cross-section whenever it is available.
| AWG | Calculated Area | Common Metric Ferrule Reference | Catalogue Note |
|---|---|---|---|
| 26 AWG | 0.129 mm² | 0.14 mm² | Nominal catalogue reference; confirm the conductor and ferrule documentation. |
| 24 AWG | 0.205 mm² | 0.25 mm² | Termnex product catalogue and packaging use AWG 24 for 0.30 mm². |
| 22 AWG | 0.326 mm² | 0.34 mm² | Termnex product catalogue and packaging use AWG 22 for 0.50 mm². |
| 20 AWG | 0.518 mm² | 0.50 mm² | Termnex product catalogue and packaging use AWG 20 for 0.75 mm². |
| 18 AWG | 0.823 mm² | 0.75 mm²; 1.00 mm² | 0.75 and 1.00 mm² both appear under AWG 18 in major ferrule catalogues; the Termnex product catalogue labels 1.00 mm² as AWG 18. |
| 16 AWG | 1.309 mm² | 1.50 mm² | The Termnex product catalogue uses the same label. |
| 14 AWG | 2.081 mm² | 2.50 mm² | The Termnex product catalogue uses the same label. |
| 12 AWG | 3.309 mm² | 4.00 mm² | The Termnex product catalogue uses the same label. |
| 10 AWG | 5.261 mm² | 6.00 mm² | The Termnex product catalogue uses the same label. |
| 8 AWG | 8.366 mm² | 10 mm² | The Termnex product catalogue uses the same label. |
| 6 AWG | 13.302 mm² | 16 mm² | The Termnex product catalogue uses the same label. |
| 4 AWG | 21.151 mm² | 25 mm² | The Termnex product catalogue uses the same label. |
| 2 AWG | 33.631 mm² | 35 mm² | The Termnex product catalogue uses the same label. |
| 1/0 AWG | 53.475 mm² | 50 mm² | The Termnex product catalogue uses the same label. |
Bold rows are the 20 AWG to 10 AWG band that covers most control panel wiring. Above 1/0 AWG there is no standardized collar colour at all. See Sizes Above 50 mm².
For UL 508A panel shops, note that this table tells you which ferrule fits the conductor. It does not tell you whether that ferrule is compliant in your panel. That depends on the ferrule-and-tool pairing, covered in DIN 46228 vs UL 486F.
Complete Wire Ferrule Size Chart in mm²
Use this table if you specify conductors in mm², standard practice in the UK and Europe, where the part is usually called a bootlace ferrule. It is the master reference and covers the full DIN 46228-4 range. The calculated AWG column is geometric; the catalogue column shows how named ferrule ranges label the same metric size. For quick reference during panel assembly, the common control-panel sizes are 0.5 mm² to 6 mm², highlighted in the table. Larger sizes from 10 mm² upward are used in power distribution and heavy industrial panels.
The colors below are taken directly from the DIN colour table (Kennfarbe der Kunststoffhülse nach DIN 47002), cross-checked against a manufacturer catalogue. The standardized colour range runs 0.5 mm² to 50 mm² and stops there. See Sizes Above 50 mm² below.
| Cross-Section | Calculated AWG | Catalogue Reference | Collar Colour (DIN 47002) | Typical Application |
|---|---|---|---|---|
| 0.14 mm² | 25.64 AWG | Common: AWG 26 | Not standardised | Low-current signal wiring |
| 0.25 mm² | 23.14 AWG | Common: AWG 24 | Not standardised | Sensor and instrumentation circuits |
| 0.34 mm² | 21.81 AWG | Common: AWG 22 | Not standardised | Low-current control circuits |
| 0.50 mm² | 20.15 AWG | Common: AWG 20; Termnex product label: AWG 22 | White | Sensors and PLC I/O wiring |
| 0.75 mm² | 18.40 AWG | Common: AWG 18; Termnex product label: AWG 20 | Grey | Control and auxiliary circuits |
| 1.00 mm² | 17.16 AWG | AWG 18 | Red | Control panels and general wiring |
| 1.50 mm² | 15.41 AWG | AWG 16 | Black | Internal panel power wiring |
| 2.50 mm² | 13.21 AWG | AWG 14 | Blue | Power circuits and feeders |
| 4.00 mm² | 11.18 AWG | AWG 12 | Grey | Larger power conductors |
| 6.00 mm² | 9.43 AWG | AWG 10 | Yellow | Higher-load panel wiring |
| 10 mm² | 7.23 AWG | AWG 8 | Red | Heavy-duty terminations |
| 16 mm² | 5.20 AWG | AWG 6 | Blue | High-current distribution |
| 25 mm² | 3.28 AWG | AWG 4 | Yellow | Power distribution panels |
| 35 mm² | 1.83 AWG | AWG 2 | Red | Heavy industrial terminations |
| 50 mm² | 0.29 AWG | AWG 1/0 | Blue | Main feeders and switchgear terminations |
| 70 mm² | ≈ 2/0 AWG | AWG 2/0 | No standard colour | Heavy power distribution |
| 95 mm² | ≈ 3/0 AWG | AWG 3/0 | No standard colour | Heavy power distribution |
| 120 mm² | ≈ 4/0 AWG | AWG 4/0 | No standard colour | Heavy power distribution |
| 150 mm² | Beyond 4/0 AWG | 250/300 MCM | No standard colour | Heavy power distribution |
A note on repeating colors: Within the standardized 0.5–50 mm² range, gray appears at 0.75 mm² and 4.00 mm². Red appears at 1.00 mm², 10.00 mm², and 35.00 mm². Blue covers 2.50 mm², 16.00 mm², and 50.00 mm². DIN 46228-4 assigns each size a collar colour identified per DIN 47002; colour remains a visual aid, not a unique identifier across the full range. Colours below 0.5 mm² are manufacturer-specific. In a panel shop handling multiple wire gauges, color alone will mislead you. Read the size marking on the collar.
Sizing Differences: Insulated, Uninsulated, and Twin
The three ferrule types share the same metal barrel dimensions for a given cross-section. What changes is the collar and entry geometry. If that choice has not been made yet, start with the side-by-side product comparison. Every dimension referred to below (pin length, overall length, collar width and height, barrel bore) is then tabulated size by size on the insulated, twin, and non-insulated product pages.
Insulated ferrules (DIN 46228-4) have a plastic collar extending beyond the barrel. The collar adds 2–4 mm to overall length and widens the entry point. The actual entry diameter you need to clear at the terminal face is the collar OD, not the barrel OD. Check terminal entry specs before assuming an insulated ferrule fits where an uninsulated one did.
Uninsulated ferrules (DIN 46228-1) are bare copper sleeves with no collar. Overall length is shorter by the collar dimension. Where terminal entry is tight or the design standard calls for bare sleeves, uninsulated ferrules are the default. Visually they carry no color identification, so bin discipline matters more.
Twin ferrules take two conductors of the same cross-section into a single barrel — one connection point, two wires. The barrel width is roughly double a single ferrule at the same gauge, and not every terminal accepts them. Spring-cage terminals generally accept twins well; screw terminals need to be verified against the manufacturer’s datasheet. Never mix conductor sizes in a twin ferrule: the smaller wire will sit loose in the barrel and crimp poorly.
| Type | Standard | Collar | Entry Width | Color ID |
|---|---|---|---|---|
| Insulated | DIN 46228-4 | Yes | Collar OD | Yes |
| Uninsulated | DIN 46228-1 | No | Barrel OD | No |
| Twin | DIN 46228-4 | Yes | Wider barrel | Yes |
Figure 2 illustrates the dimensional differences between insulated, uninsulated, and twin ferrules at the same conductor cross-section.
Barrel Length and Why It Matters
Cross-section gets most of the attention during ferrule selection. Barrel length gets ignored until something goes wrong.
The barrel must seat fully inside the terminal’s wire entry shaft. Too short and the crimp sits partially outside the clamping zone — contact area drops and resistance climbs. Too long and the barrel bottoms out before the terminal clamps down, leaving the connection loose.
How to match barrel length to your terminal:
Check the terminal manufacturer’s recommended strip length. Strip length and barrel length are paired: strip too short and bare copper won’t fill the barrel; strip too long and exposed conductor extends past the ferrule end. Most terminal datasheets list an accepted wire strip length, and that number tells you the barrel length you need.
Common bootlace ferrule barrel lengths in control panel work:
| Barrel Length | Typical Terminal Match |
|---|---|
| 8 mm | Compact screw terminals, PLC I/O blocks |
| 10 mm | Standard UK-series screw terminals |
| 12 mm | Larger screw terminals, spring-cage blocks |
| 14–18 mm | Power terminals, 10 mm² and above |
A common mistake in busy panel shops: a technician grabs 10 mm ferrules for a terminal that specifies 8 mm strip length. The barrel bottoms out inside the terminal shaft before the clamping screw reaches torque. The connection feels tight but the ferrule isn’t fully clamped. Six months later the terminal runs hot.
Spring-cage terminals like WAGO 221 or Phoenix Contact PT series publish accepted ferrule dimensions in their datasheets. Screw terminals are less sensitive to barrel length variation but still have a minimum insertion depth. When in doubt, pull the terminal datasheet and match to the strip length specification. As shown in Figure 3, strip length must equal barrel length for the conductor to fill the sleeve completely.
Sizes Above 50 mm²
The DIN colour table ends at 50 mm². That is not an omission in most datasheets. There is no standardized collar colour above 50 mm², so any colour you see on a 70 mm², 95 mm², 120 mm² or 150 mm² ferrule is that manufacturer’s own choice.
Two practical consequences:
Never specify a large ferrule by colour. Below 50 mm² a blue collar reliably means 2.5 mm² or 16 mm² or 50 mm² within DIN. Above it, a yellow collar on one brand’s 70 mm² may be another brand’s 150 mm². Order by cross-section and barrel length, and confirm against the part number.
Mixed-brand panels get worse, not better, at large sizes. If a panel is re-terminated years later with a different supplier’s ferrules, the large-conductor colours will not match the originals. Document the cross-sections on the wiring schedule rather than relying on what the installer can see.
Insulated ferrules are commonly manufactured up to 150 mm², and uninsulated (bare) sleeves up to 185 mm². Above 50 mm² the crimp also moves to hex or deep-indent profiles and needs a hydraulic or long-arm tool. A standard control-panel crimper will not close these sleeves.
The Three Colour Standards: DIN, French NF, and UL
Here is the single most common source of confusion in ferrule procurement: the same cross-section has different collar colours in different markets, and all of them are correct.
Major manufacturers publish two or three parallel colour series side by side:
- DIN 46228-4 (German, colour table per DIN 47002), the dominant European and global reference
- NF C 63-023 (French), used in France and parts of French-influenced markets
- UL 486F (North American), a listing standard that does not define a colour system at all
Two parallel standards are why a 1.5 mm² ferrule arrives black from one supplier and red from another. Neither is wrong. Black is DIN; red is a common French-market colour at that size.
| Cross-Section | DIN 46228-4 | Common French (NF) colour |
|---|---|---|
| 0.50 mm² | White | Orange |
| 1.50 mm² | Black | Red |
| 6.00 mm² | Yellow | Black |
On the French series: unlike DIN, the NF colour set is not consistently published as a complete cross-section table, and manufacturers stock only the sizes their customers actually order. The three above are the ones you will most often meet in practice. If a project specifies French colours, confirm the full list with your supplier against part numbers rather than assuming a published chart applies.
What this means when you order. Specify the standard, not the colour: “2.5 mm², 10 mm barrel, DIN 46228-4 colour” is unambiguous. “Blue 2.5 mm² ferrules” is not. It happens to be right under DIN and wrong under NF. On a drawing or a bill of materials, always cite the cross-section and the standard together.
Figure 4 shows how the same three cross-sections carry different collar colours under the DIN and French series, and why UL sits outside the comparison entirely.
DIN 46228 vs UL 486F: Which Standard Applies to You
Most ferrule datasheets cite DIN 46228. North American panel shops working under UL 508A certification will also encounter UL 486F. The two standards are not interchangeable, and they don’t use the same color system.
DIN 46228 is a product conformance standard. It defines ferrule dimensions, material requirements, and test methods. Part 1 covers uninsulated ferrules; Part 4 covers insulated ferrules with plastic collars. The 2020 revision (DIN 46228-4:2020-03{target=”_blank” rel=”noopener noreferrer”}, with a 2023 corrigendum) added a maximum sleeve hardness requirement of 105 HV, a manufacturing quality control measure that prevents overly hard copper sleeves from crimping inconsistently. Compliance is declared by the manufacturer against the standard.
UL 486F works differently. It’s a listed-system standard: the ferrule and crimping tool are tested and certified together as a matched pair. A ferrule that passes UL 486F testing with Tool A is not automatically certified with Tool B. For UL 508A panel shops, this matters — an inspector can reject a panel if the ferrule-tool combination isn’t from a UL 486F listed pairing{target=”_blank” rel=”noopener noreferrer”}, regardless of how the crimp looks.
Color coding: DIN 46228-4 defines a specific cross-section-to-color table, from 0.5 mm² to 50 mm². UL 486F does not specify a colour system at all. It is a listing standard for the ferrule-and-tool pair, not a marking standard. Products built for the North American market may therefore follow DIN colours, French NF colours, AWG-based schemes, or manufacturer-specific coding. Never assume colour means the same thing across both systems.
| DIN 46228-4 | UL 486F | |
|---|---|---|
| Scope | Product conformance | System listing |
| Certification unit | Ferrule alone | Ferrule + crimping tool |
| Color coding | Defined, 0.5–50 mm² | Not defined at all |
| Primary market | Europe, global | North America |
| Current edition | 2020-03 + 2023 corrigendum | 2024 third edition |
If your project requires both European sizing consistency and North American compliance, specify both standards explicitly in procurement, and confirm the crimping tool is part of a UL-listed pairing for the ferrule you’re buying.
How to Select the Right Wire Ferrule in 5 Steps
Ferrule selection takes two minutes when you work through it in order. Most errors come from skipping steps: grabbing by color, guessing on barrel length, or ignoring the terminal datasheet.
Step 1: Confirm your conductor cross-section Measure in mm² or AWG. Don’t estimate. A 1.5 mm² conductor crimped into a 2.5 mm² ferrule will sit loose in the barrel regardless of how the crimp looks from outside.
Step 2: Check your terminal’s accepted conductor type Some terminals accept fine-stranded conductors directly. Others require ferrules. Spring-cage terminals in particular often specify whether ferrules are permitted, preferred, or mandatory. Find this in the terminal datasheet, not the product photo.
Step 3: Read the strip length specification The terminal datasheet lists an accepted strip length. That number determines your barrel length. Match them.
Step 4: Choose insulated, uninsulated, or twin Insulated for most control panel work. Uninsulated where entry geometry is tight or the design standard specifies bare sleeves. Twin only when two same-gauge conductors share one connection point. Confirm the terminal accepts twin ferrules before crimping.
Step 5: Verify compliance requirements CE-marked installation or European export: reference DIN 46228-4:2020-03. UL 508A certified panel shop: confirm the ferrule and your crimping tool form a UL 486F listed pairing. Both markets: specify both standards in procurement.
FAQ
What wire ferrule size do I need for 14 AWG wire?
14 AWG corresponds to 2.5 mm². Under DIN 46228-4, the correct ferrule is 2.5 mm² with a blue insulation collar. Confirm the barrel length against your terminal’s strip length specification. Standard options are 10 mm or 12 mm for most screw and spring-cage terminals at this gauge.
What size bootlace ferrule do I need for 2.5 mm² cable?
A 2.5 mm² bootlace ferrule, blue collar under DIN 46228-4. In North American catalogues the same part is listed as a wire ferrule for 14 AWG. Pick the barrel length from your terminal’s strip length spec. 10 mm and 12 mm are the usual options at this cross-section. The names differ by market, but bootlace ferrule, wire ferrule, cable ferrule and cord end terminal are the same component, and there is no separate part to order.
Why does the same color appear on different wire ferrule sizes?
DIN 46228-4 reuses colors across its standardized 0.5–50 mm² range. Gray covers 0.75 mm² and 4.00 mm². Red appears at 1.00 mm², 10.00 mm², and 35.00 mm². Blue appears at 2.50 mm², 16.00 mm², and 50.00 mm². The color is a visual aid within a working size range, not a unique identifier across all sizes. Always read the size marking printed on the ferrule collar. Color alone is not reliable when your panel uses multiple wire gauges.
Why did my 1.5 mm² ferrules arrive red instead of black?
Because they follow the French colour series rather than DIN. Under DIN 46228-4 a 1.5 mm² collar is black; the common French-market colour at that size is red. Neither supplier is wrong; two colour standards coexist. The same happens at 0.5 mm² (white under DIN, orange under the French series) and 6 mm² (yellow under DIN, black under the French series). Check the cross-section marking on the collar, and specify the standard by name on your next order.
What colour is a 70 mm² wire ferrule?
There is no standard answer. The DIN colour table ends at 50 mm², so collar colours on 70 mm² and larger ferrules are chosen by each manufacturer independently. Order large ferrules by cross-section and barrel length against a part number, never by colour, and expect colours to differ if you re-terminate a panel with a different brand later.
Can I use a DIN 46228-4 ferrule in a UL 508A certified panel?
Possibly, but not automatically. UL 508A panels require ferrules from a UL 486F listed ferrule-and-tool pairing. A ferrule marked DIN 46228-4 compliant may or may not appear in the UL Product iQ database. Check the UL listing before using it in a certified panel shop. An inspector can reject the panel if the pairing isn’t listed, regardless of crimp quality.
What is the difference between barrel length and strip length?
Barrel length is the metal sleeve length of the ferrule. Strip length is how much insulation you remove from the wire before inserting it. The two must match: strip length equal to barrel length fills the barrel completely with conductor. Strip too short leaves an air gap inside the barrel; strip too long leaves bare copper exposed beyond the ferrule end.
When should I use a twin wire ferrule?
Use a twin ferrule when two conductors of the same cross-section need to share a single terminal connection point. Twin ferrules are common in PLC wiring where a control signal feeds two devices from one terminal. Confirm the terminal accepts twin ferrules before crimping: spring-cage terminals generally do, screw terminals need datasheet verification. Never use a twin ferrule with two different conductor sizes.
Do wire ferrules work with all terminal block types?
Not universally. Screw terminals accept ferrules across most sizes. Spring-cage terminals specify accepted ferrule dimensions in their datasheets and may restrict collar OD or barrel length. Push-in terminals designed for solid conductors often don’t accept ferrules at all. Always check the terminal manufacturer’s datasheet for accepted conductor termination methods before selecting a ferrule type.
Termnex Wire Ferrules
Termnex supplies DIN 46228-4 compliant wire ferrules (bootlace ferrules, if that is the term on your drawing) across the full size range, not only the common control panel sizes:
- Insulated wire ferrules: 0.3 to 150 mm² (AWG 24 – 300 MCM), 56 listed sizes with the complete dimension table
- Twin wire ferrules: 2×0.5 to 2×16 mm²
- Non-insulated wire ferrules: 0.3 to 185 mm², beyond where the insulated range stops
Collars are nylon PA66 rather than polypropylene, and both DIN and French colour options are available. Tell us which standard your drawing cites and we will match it. Ferrules are RoHS compliant and supplied with a CE Declaration of Conformity. Samples are available on request. Contact us at termnex.com/contact-us to discuss your project requirements or request a quote.
