Compression Lug Die Index and Color Code Guide: Matching the Die to the Lug
Sep 29, 2026
A compression lug is only listed when it is crimped with the tool and die it was tested with. The die index and color code are how crews get that right at speed. This is the working reference for the 12 ton U-die system used by Burndy, Greenlee, Thomas & Betts and the Conversions Tech CTTY series.
How the system works
- Every compression lug and splice carries a die index number (for example 42) and a color (pink). It is printed or stamped on the barrel.
- The matching die has the same index and color. Crimp with that die and the lug is within its UL 486A/B listing.
- After crimping, the die leaves the index number embossed on the barrel. That is the inspection mark. No number, no proof.
- Long barrel lugs take two crimps with the same die, starting at the tongue end and working toward the conductor end.
Index and color by conductor (copper, Class B)
| Conductor | Index | Color | CT die |
|---|---|---|---|
| 8 AWG | 21 | Red | CTTY-8AWG |
| 6 AWG | 24 | Blue | CTTY-6AWG |
| 4 AWG | 29 | Gray | CTTY-4AWG |
| 3 AWG | 33 | Brown | CTTY-3AWG |
| 2 AWG | 33 | Brown | CTTY-2AWG |
| 1 AWG | 37 | Green | CTTY-1AWG |
| 1/0 AWG | 42 | Pink | CTTY-10AWG |
| 2/0 AWG | 45 | Black | CTTY-20AWG |
| 3/0 AWG | 50 | Orange | CTTY-30AWG |
| 4/0 AWG | 54 | Purple | CTTY-40AWG |
| 250 kcmil | 62 | Yellow | CTTY-250 |
| 300 kcmil | 66 | White | CTTY-300 |
| 350 kcmil | 71 | Red | CTTY-350 |
| 400 kcmil | 76 | Blue | CTTY-400 |
| 500 kcmil | 87 | Brown | CTTY-500 |
| 600 kcmil | 94 | Green | CTTY-600 |
| 750 kcmil | 99 | Black | CTTY-750 |
| 1000 kcmil | 115 | Orange | CTTY-1000 |
Colors repeat as the index climbs, so the number is the authority. Always match the index printed on the lug. Flex lugs for DLO and fine strand conductor use their own index; read the barrel.
Tools
- 12 ton hydraulic or battery crimper with U-dies for 8 AWG through 1000 kcmil. This is the standard on commercial, industrial and utility work.
- Dieless crimpers exist but the lug must be listed for dieless crimping; most compression lugs are not.
- Hand tools for 8 and 6 AWG only, and only where the lug is listed for that tool.
Inspection checklist
- Index number embossed on the barrel and matching the lug marking.
- Correct number of crimps: one on standard barrel, two on long barrel.
- No strands cut or folded back at the barrel mouth.
- Crimp centered on the barrel, not on the inspection window or the tongue.
- Bolt torqued to the equipment manufacturer's value, NEC 110.14(D), with a calibrated wrench.
Buying dies
Buy the die with the first box of a new lug size. The Conversions Tech 19-piece die kit (CTCDIEKIT) covers index 21 through 115 in a steel case; single dies are stocked by index. All fit Burndy, Greenlee, T&B and CT 12 ton crimpers. Same-day shipping on in-stock items.
Related: Which lug for which gauge · DLO lugs vs standard lugs · Lug applications guide
