| Severity index (S) | Protection measures | Environment |
| 11 | Defective or unknown protection | Submerged |
| 10 | Medium sensitivity device with earthing | Submerged |
| 9 | Defective or unknown protection | Wet |
| 8 | Defective or unknown protection | Dry |
| 7 | Medium sensitivity device with earthing | Wet |
| 6 | High sensitivity device | Submerged |
| 5 | High sensitivity device | Wet |
| 4 | Medium sensitivity device with earthing | Dry |
| 3 | PELV | Submerged |
| 2 | PELV | Wet |
| 1 | High sensitivity device | Dry |