ballast city commute commuter electric gantry glasgow overhead platform power rail railway station steel suburban track train travel work advice advising alert black communicate communication concern danger electric-power electrical electricity electricity-power-lines energy equipment height high high-voltage information informing power-lines power-supply protect protection risk risks risky safety sign strength supply warning wires wiring yellow amp bombillo bulb ceiling illuminate illuminating light light bulb lumen lumens luz radiance radiat shine socket watt AC cable current distribution installation insulation insulator line lines pole post voltage wire conductor copper dangerous grid pylon substation transformer transmission volt chock fence net sundtech