alps Bolzano bozen cars high Italy lines power rails railway railways summer tracks transportation voltage cable cables dangerous electric electricity insulator pole poles train wire wires wiring clouds conductor grid metal pylon sky tower transmission burst danger energy explosion high voltage inexpected light lightning lights ray of light sudden volt current distribution electrical facility station sundtech supply AC blue suspended chock chocking fence secure security warning insulators arrow attention beware black directions german germany Greek industrial Multilingual ocher pictogram russian sign signs turkish yellow