HYDROPIC : in order to be able to act safely on an underground cable after having taken all safety precautions, it is absolutely necessary to make sure that same cable is de-energized since there is always a risk to act erroneously on a neighbouring cable which is energized. This safety precaution is carried out with a cable pricker, it is a destructive (should the cable be actually energized) CAT operation as recommended by the C.C.P.-UTE C18-150 specification together with the operation documents applicable to the transmission networks.