Compression Lug Die Chart: Die Index Numbers and Color Codes by Conductor Size for 12-Ton Crimpers (Burndy, T&B, Greenlee, Conversions Tech)
Sep 10, 2026
Summary: Compression lugs are crimped with a numbered die that matches the conductor size. The die index number is stamped on the lug barrel and on the die; the color band on the lug matches the color on the die. For 12-ton U-die crimpers the copper index runs from 5 (8 AWG) to 125 (1000 kcmil). Short-barrel lugs take one crimp; long-barrel lugs take two. Using the wrong die is the most common cause of a failed pull test or a hot termination.
How to read a compression lug
A UL 486A/B listed compression lug is marked with: the conductor size it fits (for example 4/0 AWG), the die index number to crimp it with (for example 87), a color band matching that die, the number of crimps, and the conductor class it is listed for (Class B, or B through M for flex-rated long barrels). The die index is a standard shared by Burndy, Thomas and Betts, Panduit, Ilsco, Greenlee and Conversions Tech, so a die from any of them with the same index makes a listed crimp on a lug carrying that index.
Copper compression lug die chart, 12-ton U-die
| Conductor | Die index | Color | Crimps, short barrel | Crimps, long barrel |
|---|---|---|---|---|
| 8 AWG | 5 | Red | 1 | 2 |
| 6 AWG | 7 | Blue | 1 | 2 |
| 4 AWG | 8 | Gray | 1 | 2 |
| 3 AWG | 10 | Brown | 1 | 2 |
| 2 AWG | 11 | Green | 1 | 2 |
| 1 AWG | 13 | Pink | 1 | 2 |
| 1/0 AWG | 15 | Tan | 1 | 2 |
| 2/0 AWG | 16 | Olive | 1 | 2 |
| 3/0 AWG | 18 | Ruby | 1 | 2 |
| 4/0 AWG | 21 | White | 1 | 2 |
| 250 kcmil | 24 | Red | 1 | 2 |
| 300 kcmil | 26 | Blue | 1 | 2 |
| 350 kcmil | 29 | Brown | 1 | 2 |
| 400 kcmil | 31 | Green | 1 | 2 |
| 500 kcmil | 33 | Pink | 1 | 2 |
| 600 kcmil | 37 | Black | 2 | 3 |
| 750 kcmil | 42 | Orange | 2 | 3 |
| 1000 kcmil | 45 | Purple | 2 | 3 |
Index numbers above follow the Burndy Hyground and Thomas and Betts Color-Keyed system used by 12-ton dieless-compatible U-die tools. Some manufacturers also print the P-number or the Greenlee equivalent on the lug; the color band is the cross-check that works across all of them. Always crimp to the index and color stamped on the lug you are holding; the marking on the lug governs.
Aluminum and dual-rated compression lug dies
Aluminum conductors use a larger barrel for the same AWG, so a dual-rated AL9CU compression lug carries a different index than a copper lug of the same conductor size, typically the copper index for one to two sizes larger. A 4/0 AWG aluminum lug is crimped with the die for 250 or 300 kcmil copper; the lug marking states which. Aluminum barrels are factory-filled with oxide inhibitor and should be crimped without wiping it out.
Crimp sequence
- Strip to the barrel depth marked on the lug plus 1/16 in; do not nick strands.
- Insert the conductor to the inspection hole or the barrel bottom; strands must be visible in the hole.
- Short barrel: one crimp centered on the barrel. Long barrel: first crimp nearest the tongue, second toward the cable end, dies fully closed each time. Rotate 90 degrees between crimps on hex dies.
- Check the die index stamped by the crimp against the lug marking, and confirm there is no flash more than 1/32 in.
- On aluminum, brush the strands and apply inhibitor before insertion; wipe excess after crimping.
What happens with the wrong die
A die one size too large under-compresses the barrel: the strands are not cold-welded, resistance rises, and the termination heats under load; it also fails the UL 486A pull test. A die one size too small over-compresses: the barrel cracks or the strands are cut at the crimp edge, which shows as a broken conductor a few months later. Both are invisible from outside once heat shrink goes on, which is why the die index is stamped into the barrel by the crimp.
Quick answers
Can I use a Burndy die on a Conversions Tech lug? Yes, when the index number and color on the die match the marking on the lug. The index is a shared standard.
What die is 4/0 copper? Index 21, white, one crimp on a short barrel and two on a long barrel, for 12-ton U-die tools.
Do battery cable lugs use the same dies? Yes for tinned copper battery lugs; crimp to the index stamped on the lug, which is usually one size larger than the AWG because fine-strand cable has a larger diameter.
Is a dieless crimper acceptable? Only if the lug is listed for dieless crimping; most are listed for a specific die. Check the lug marking and the crimper's listing.
Compression lugs and matching 12-ton die sets are stocked by Conversions Tech, 8 AWG to 1000 kcmil, short and long barrel, one-hole, two-hole and flag, all UL 486A/B listed and marked with die index and color. Selection help: compression vs mechanical lugs; cross-reference by Burndy, T&B or Panduit number at the cross-reference tool.
