How to Make a Split-Wired Receptacle to Double Power
Wiring electrical outlets is a common, straightforward electrical project. With this task, the power from one circuit is delivered to a duplex outlet and is shared between the two sections of the outlet. But when you have a greater need for power at this outlet and want to avoid nuisance breaker trips, you may want to split up this outlet between two circuits.
What Are Split Outlets?
A split outlet is a duplex electrical outlet that is split into two sections so that each section receives power from its own separate hot or powered wire. The outlet body itself is not physically split; it remains intact. However, a small section of the outlet is physically split to separate the functions.
In homes with 120V systems, an outlet wired like this will have 120V in the top section and 120V in the bottom section, for a total of 240V coming into that outlet. This is in contrast to the more commonly found electrical outlet that has 120V shared between the two sections.
Most 15- and 20-amp (A) outlets are called duplex outlets because the top and the bottom sections can operate separately. Upon purchase, duplex outlets are not operating in duplex fashion. A terminal fin—a tiny strip of copper or most likely brass—connects the two sections. When one section receives power, so too does the other section because of that copper or brass strip. Severing the terminal fin allows for separate feed conversion.
Split outlets let you bring twice the amount of power to a single receptacle. This is especially valuable in kitchens, where you often find high-demand appliances. For example, the top section of a split outlet can power a microwave oven, with the bottom section powering a toaster. This reduces the chance of circuit breakers flipping off because of excessive power draws.
Codes and Regulations
Most communities require that you apply for an electrical permit for any type of electrical circuit and service extension or alteration. Wiring a split outlet in most cases will be either new construction work or an alternation, both of which require a permit.
When to Wire a Split Outlet
While wiring the split outlet is fairly easy, running the 12/3 or 14/3 electrical wire to the electrical box will not be easy if the walls are closed. The best time to wire a split outlet is when the walls are open, prior to installing the drywall.
Always be sure to turn off the circuits that you will be working with and double-check with the voltage tester that the wires are not live.
The 12/3 and 14/3 electrical wires are not always interchangeable. If you are working with a 20 A circuit breaker and a 20 A-rated outlet, be sure to use 12 gauge wire. (Note: the National Electric Code allows 15 amp outlets to be used on 20 amp residential circuits.) If you are working with a 15 A circuit breaker and a 15 A-rated outlet, you may use 14 gauge wire, though you can use 12 gauge wire, as well. (Note: You are not allowed to use 20 amp rated outlets on a 15 amp circuit breaker.)
What You'll Need
Equipment / Tools
- Voltage tester
- Electrical wire stripper
- Electrical wire ripper
- Needlenose pliers
- Flathead and Phillips screwdrivers
- 12/3 or 14/3 NM electrical wire
- Electrical box
- Duplex electrical outlet
Turn Off the Circuit Breaker
At the service panel, turn off the circuit breakers controlling the wires that run to the project area. Use the voltage tester to ensure the wires are not live.
Sever the Terminal Fin
With the needlenose pliers, clip the copper terminal fin connecting the two sections. To do this, hold the fin with the nose of the pliers and rock back and forth until the fin breaks free.
Check the Terminal Fin
Make sure that you remove all remnants of the copper terminal fin. Even the thinnest copper remnant may still create a connection between the two sections and result in an electrical short.
Rip the Cable Sheathing
With the cable ripper, rip back the NM electrical cable to expose about 4 or 5 inches of wire.
Strip the Wire Casing
Strip back the casing on each electrical wire about 3/8-inch to expose bare copper wire.
Wire the Ground
Attach the bare copper ground wire to the green ground screw on the outlet.
Wire the Neutral
Wire the white neutral wire to either of the two silver terminals on the outlet and flip over the outlet.
Wire the Black and Red Wires
Wire the black wire to one of the gold colored terminals. Wire the red wire to the other gold terminal screw on the outlet.
Install the Outlet
Screw the outlet into the electrical box. Use a Phillips head screwdriver to turn the two screws clockwise, thus drawing the outlet toward the direction of the electrical box.
Install the Faceplate
With a flathead screwdriver, screw the faceplate into place. Be careful when turning as this is a painted screw and can easily be scratched if you turn with too much force. Also, many outlet covers are made of breakable plastic and too much tightening will break the cover.
What is a split-wired receptacle?
A split-wired receptacle, or split outlet, is a duplex outlet in which each section is powered by its own hot wire. It's a common setup to allow you to control half the outlet by a switch, with the other half having power at all times.
What is the difference between a duplex receptacle and a split duplex receptacle?
A duplex receptacle has spaces to plug in two electronic devices at once. A split duplex receptacle still has room for two plugs, but each plug receives power from a separate wire, which doubles the total power going to the outlet.
How do you know if a receptacle is split?
The easiest way to check is to see whether a switch controls one half of the outlet—a common use for a split outlet. Otherwise, you will have to check the receptacle's wiring to see how many hot wires are powering it.