| Gas | Normal ppm | Abnormal ppm | Interpretation |
| H2 | 150 | 1000 | Arcing corona |
| CH4 | 25 | 80 | Sparking |
| C2H6 | 10 | 35 | Local overheating |
| C2H4 | 20 | 100 | Severe overheating |
| C2H2 | 15 | 70 | Arcing |
| CO | 500 | 1000 | Severe overloading |
| CO2 | 10,000 | 15,000 | Severe overloading |
| TDCG | 720 | 2285 |