Wiring Color Codes for McLean County 4-H Projects Common colors for DC wire Black White Red DC Battery Connections Black wire always to negative terminal White wire always to positive terminal DC Connections Black wires identify negative or hot wires. Switches connect on negative side of battery to the load (light). White wire is used to identify the positive polarity. Switch White Black Black Black This Knife switch shows black wire in and black wire out. This type of miniature lamp socket has a brass colored screw and a silver screw. Black wires will connect to brass and white wires connect to silver. Red wire is also like black and can be used to identify the negative side or switch side of a circuit. This is a 3-way circuit. Red and black wires are used to identify the path of current and are on the negative side. White Black Black 3-way switch Black Red This is a 3-way/4-way circuit. Red and black wires are used to identify the path of current and are on the negative side. The lights are in series. The black wire in between the lights could also be red. Black 4-way switch Common Wire for AC Type 1 Ground Romex Cable 2 conductor with a ground Black White Common Wire for AC Type 2 Black Ground Romex Cable 3 conductor with a ground White Red AC Connections Wiring an Outlet Ground green terminal White silver terminal (neutral) Black (hot) Outlet other side: Black wire on brass terminal (hot) AC Connections Wiring a Switch Neutrals tied together Black (hot) Black (hot) Ground green terminal AC Connections Wiring a 3-way switch Wiring of a 3-way switch using 3 conductor Romex cable. This is an exception where white can is terminated on the switch and is a HOT (live) wire! A closer look a the 3way switch. Notice the dark screw, that is the common position. The other side of the 3-way switch.