barrier colors colours danger electricity sign. electric fence warning wires death fence security sign black chock current dangerous electric electrical high installation net power station sundtech volt voltage yellow cable conductor copper distribution grid insulator pylon railings substation supply transformer transmission wire electrocute electrocution hazard keep out metal warn alert amperage amps area backdrop background bolt brown caution copy discharge energy grunge grungy hazardous icon industry information isolated lightning painted plank planks risk shock space square steel symbol triangle volts wall white wood wooden chocking secure