Things You'll Need
14-3 NM-B ROMEX® cable
Plastic splice caps
ROMEX® 14-3 cable refers to a type of electrical wiring cable used inside a home in dry areas, such as attics and inside walls. This cable contains four conductors: a black (hot) wire, a red (hot) wire, a white common wire and a ground wire. All four conductors are wrapped in a plastic sheath. ROMEX® 14-3 is designed for use on circuits that require 220 to 240 volts from the power panel. An example is a clothes dryer. ROMEX® 14-3 can also be used to power two different circuits. The trick is that each circuit uses a different hot wire, but they share the common wire and ground wire. This technique is used more for lighting circuits.
Shut off power to the main power panel. Run ROMEX® wire from the main power panel to the first of the two light fixtures that will be on different circuits. At the first light fixture, connect the black wire to the light fixture's black wire and top the splice with a plastic splice cap. Connect the white common wire to the white common wire of the light fixture, but do not place a splice cap yet. Connect the ground wires if the light fixture has one.
Run a second section of ROMEX® 14-3 cable from the first light fixture to the second light fixture. At the first light fixture, connect the common white wire that runs to the second fixture to the splice with all of the other common wires and add a splice cap. Also, connect that ground wire to all the other ground wires and add a splice cap. Place a splice cap on the end of the black wire that runs to the second light fixture. That wire will remain unused. Secure the first light fixture and move to the second light fixture.
Place a splice cap on the black wire that runs back to the first light fixture. That wire will not be used. Connect the red (hot) wire to the black hot wire of the light fixture and add a splice cap. Connect the white common wire of the ROMEX® cable to the white common wire of the light fixture and add a splice cap. Connect the ground wires if applicable and add a splice cap.
Secure the light fixture and move to the main power panel. In the main power panel, choose to use either two separate circuit breakers for the red and black hot wires or a single double breaker that would shut off the red and black hot wires at the same time.
Remove the breaker cover and knock out a single or double slot in the cover. When using two separate breakers, connect the black (hot) wire to one breaker and connect the red (hot) wire to the second breaker. When using a single double breaker, connect the black wire to first terminal on the breaker, and connect the red wire to the second terminal on the breaker. Connect the white common wire and the ground wire to the common bar in the power panel.
Push the breaker into the position corresponding to the slots that were knocked out on the breaker cover.
Replace the breaker cover and turn on the power.
Test all wires for voltage before touching. Working inside a power panel is dangerous. Pay attention and be aware of which parts of the power panel that have active voltage at all times.