The dynamic behaviour of a double transferred are is experimentally analysed. The are chamber is equipped with four optical fibers aimed at the observation of are space-time fluctuations. Terminal voltages and currents are also recorded. A particular low frequency behaviour of the are is pointed out. It is characterized by erratic skips from rotating to quasi stable fastening on the primary nozzle-shaped anode. In either case the are root looks rather evenly distributed than located in a definite position. The disappearing of the HF fluctuations when replacing the anode material by a better heat conductor material confirms the important stabilizating role played by the electrode cooling.