The TESLA 4FP 153 47 / 4FP 153 48 telephones are designed for telephone communication in underground workings (mines, coal pits) where mine gas (methane) and coal dust are present or may occur.
Their intrinsically safe "ia" explosion protection type, high IP66 dust and water resistance rating, and bright, highly visible color enable reliable operation even in the most demanding working conditions.
| Supply voltage, V | up to 90 |
| Max. ringing sound level, dB/0.5 m | >98 |
| Temperature range, °C | -30 to +60 |
| Ingress protection | IP66 |
| Explosion protection | PO Exia |
| Relative air humidity, % | up to 100 |