What Is the Red Wire for in an Electrical Outlet? | Hunker In standard 120-volt wiring, the hot wire is black, but it can also be red. In most cases, you see a red wire in an outlet box only in special circumstances. One is that the outlet is a 240-volt one, which requires an extra hot wire. Another is that the box is on a circuit three-way switch loop. What Is the Red Wire for When Installing a Light Fixture The exact purpose of a red wire for a light fixture can vary. Except in rare cases, it is a hot wire or a switched hot wire. Check the wire with a non-contact voltage tester with the power and How To Wire a 3 Way Light Switch | Family Handyman Red and blue wires link traveler terminals of both switches. The red wire, which is connected to the first switch’s common terminal, leads back to the fixture. Figure B: Three Way Switch Wire Diagram—Power to Light Switch. This three way switch wiring diagram shows how to wire the switches and the light when the power is coming to the lightAuthor: The Family Handyman 4 Ways to Wire a Breaker Circuit - wikiHow Run wire conduit from the receptacle to the circuit box. The type of wire conduit depends on the receptacle you’re installing. If you’re using a single-pole circuit breaker, then you can use a 14/2 conduit, which has 3 wires that are a 14-gauge diameter.