arrow attention beware black danger directions electricity energy high high voltage industrial lightning pictogram power sign signs voltage warning yellow aged bolt decal electric grunge surface texture volt weathered barbed wire fence secure security warn wire electric-power electricity-poles electricity-power-lines equipment height high-voltage high-voltage-equipment insulators light power-poles power-supply strength sub-station supply transformers wires wiring electric power electricity poles electricity power lines high voltage equipment house wiring power pole street light