For higher voltage building systems (for example typical 277/480V three-phase wiring), common field practice uses Brown, Orange, and Yellow for the three phases. Ever opened up a light switch or looked inside an outlet box and felt a little overwhelmed? You're met with a tangle of black, white, red, and copper wires, and suddenly, your simple DIY project feels like trying to defuse a bomb in a movie. Which wire goes where? Does it even matter? The answer. Vista Underground Distribution Switchgear features load-interrupter switches for switching 600- or 900-ampere main feeders and microprocessor-controlled arc-spinners or vacuum fault interrupters for switching and protection of 600- or 900-ampere main feeders and 200-, 600-, or 900-ampere taps. A black wire is typically used to carry electrical power to outlets, switches, lights, or equipment. What Does Black Wire Mean? In most cases, a black wire means the wire is intended to deliver electricity from the electrical panel to whatever device is connected to it. These standardized colors. 8 essential formulas with worked examples - Ohm's Law, Watt's Law, voltage drop, transformer ratio. A printable 2-page reference card sent to your inbox.