RESIDENTIAL WIRING COLOR CODING (CABLE WIRING) BASICS AND TUTORIALS

Color Coding (Cable Wiring)
The conductors in nonmetallic-sheathed cable (Romex) are color coded with insulation as follows:

2-wire: one black (“hot” phase conductor)one white (grounded “identified” conductor)one bare, covered, or insulated (equipment grounding conductor)

3-wire: one black (“hot” phase conductor) one white (grounded “identified” conductor) one red (“hot” phase conductor) one bare, covered, or insulated (equipment grounding conductor)

4-wire: one black (“hot” phase conductor) one white (grounded “identified” conductor) one red (“hot” phase conductor) one blue (“hot” phase conductor) one bare, covered, or insulated (equipment grounding conductor)

Four-wire nonmetallic-sheathed cable is also available with two ungrounded (“hot”) and two neutral conductors. This cable is designed for wiring two 120-volt branch circuits without using a common neutral.

This avoids the requirement of installing a tie handle on the circuit breakers or installing a 2-pole circuit breaker. This cable has the following insulated conductors:

• one black (“hot” phase conductor)
• one white with a black stripe (grounded “identified” conductor)
• one red (“hot” phase conductor)
• one white with a red stripe (“hot” phase conductor)
• one bare, covered, or insulated (equipment grounding conductor)

Manufacturers of Type MC cable also make a “home run cable.” This cable is available with 6 or 8 12 AWG conductors and with 6, 8, 12, and 16 10 AWG conductors. The insulation is THHN/THWN, so
derating [required by NEC 310.15(B)(3)] is started in the 90°C column of NEC Table 310.15(B) (16).

Table 5-1 illustrates application of derating for the number of current-carrying conductors in the home run cable. Notice that the number of currentcarrying conductors can change depending on how connections are made.