Understanding 120/240V Wiring Color Code | DoItYourself wwwyourself››Home AutomationWiring Types. Depending on where you live, the branch circuit wiring in your home will be made Black and Red Wires. According to NEC, a black or red wire must be used as an ungrounded Blue, Yellow, and Other Colors. In systems where individual conductors, or wires, are run through White Wires. A white wire is typically used as the neutral wire, or grounded conductor. For See all full list on doityourself What color should the wires be in a 120v system - answers wwwers››Modification of Old Electrical WorkIn a commercial building with 3-phase 120/208 power, ground and neutral are the same color, but there are 3 hot colors - black (a-phase) red (b-phase) and blue (c-phase).