Comparative Tracking Index (CTI) - UL 746
The voltage which causes tracking after 50 drops of 0.1% ammonium chloride solution have fallen on the material. The results of testing at 3 mm thickness are considered representative of the material's performance in any thickness.
Tracking is an electrical breakdown on the surface of an insulating material. A large voltage difference gradually creates a conductive leakage path across the surface of the material by forming a carbonized track.
Performance Level Categories (PLC) were introduced to avoid excessive implied precision and bias.
| Tracking Index (V) |
PLC |
| 600 and Greater |
0 |
| 400 through 599 |
1 |
| 250 through 399 |
2 |
| 175 through 249 |
3 |
| 100 through 174 |
4 |
| <100 |
5 |
Similar Standards
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