Home Wiring Guide - How To Wire A Switched (Half Hot) Outlet

What Is A Half Hot Outlet?

Most of the outlets in your home are of the "duplex" variety. That is, you can plug two devices into them at one time. A half hot, or switched, outlet is a duplex outlet that has one half of it permanently "hot" while the other half is switched via an ordinary wall switch. Learning how to wire a switched outlet is not difficult; it is similar to wiring a regular light fixture.

This method of wiring outlets is quite common in modern construction; a switched outlet is provided to plug a lamp into rather than providing a ceiling light fixture. They are most frequently found in living rooms, but can be put into any location where there is an outlet.

While the entire duplex outlet could be switched, only one of the two places to plug a device into is usually switched; this leaves the other half permanently powered for other uses. If you are installing a new outlet, or pulling additional wire to an existing one, please check this article about adding an outlet; it contains tips and suggestions for pulling wire to both new and existing outlets.

Preparing The Switched Outlet For Wiring

Either the square, "Decora" style or the more common semi-round may be used as a half hot outlet. You may not, however, use a GFI outlet as a half hot, although the entire outlet could be switched. It is not possible to modify the GFI so that only half of it is switched.

On the side of the outlet there is a small plate connecting the two brass screws where the wires go. This plate allows one wire to be used to power up both halves. To modify the outlet for use as a half hot, use a pair of needle nose pliers to twist and break that small plate. Break only the plate on the side with the brass colored screws; the plate connecting the two silver colored screws needs to remain intact. The pictures to the right show the detail for this.

With the plate broken, the outlet is ready for use. If you are modifying an existing installation, it is almost certain that the old outlet will serve, although if it is more than a few years old it should probably be replaced anyway. If you are purchasing a new outlet, make sure that you match the outlet ampacity (amps) to that provided by the circuit breaker for that circuit; a 15 amp breaker requires a 15 amp outlet and a 20 amp breaker should have a 20 amp outlet.

Breaking the Tab for a Half Hot Outlet

The small screwdriver is resting on the tab to be broken.
The small screwdriver is resting on the tab to be broken. | Source
A slightly different arrangement for the tab that needs broken.
A slightly different arrangement for the tab that needs broken. | Source
The tab has been broken out on this old outlet.
The tab has been broken out on this old outlet. | Source

What Kind Of Wire?

The National Electric Code requires that all lighting switch boxes contain a neutral. Whether or not a half hot outlet is for lighting could be up for discussion; it is probably wise to make arrangements to have that neutral in the switch box. A word of caution, however; if you are replacing an existing switched outlet, it most likely has a 2 wire cable between the outlet and the switch. In this case the white wire is being used as either a permanent hot or as the switched power and is not a neutral wire. It should be colored (magic marker, tape, etc) but often is not, and care must be taken to keep it separate from other white wires.

There are two possibilities for the incoming power; either in the outlet box or in the switch box. Either way, you will need a 3 wire cable to connect the two boxes. This cable will have a black, white, red and a bare, ground, wire in it.

Check the breaker that turns the circuit off; if it is a 20 amp breaker or fuse you will need 12-3 wire (12 gauge, 3 wire plus ground). If it is a 15 amp breaker you will need either that same 12-3 or 14-3 wire (14 gauge, 3 wire plus ground). You will find that the 14 gauge wire is cheaper and a little easier to handle.

Make sure you purchase enough wire - it will usually take more than you think. A good measure is to add about 20% to your best estimate. The Romex (NMC) wire you will be using is generally available in 25', 50', 100' and 250' rolls.

Wiring The Half Hot Switched Outlet

Before any work is done TURN OFF THE POWER! A non contact voltage detector can be invaluable here; it can detect power through the insulation of the wire. Make sure that the power is off - a nasty shock is not the most desirable outcome of your project.

As noted above, there are two possibilities for the incoming power; either in the switch box or in the outlet box. These will be treated separately.

Power in The Outlet Box

This is the preferred method of wiring a half hot switched outlet. If power is coming from the switch it is most likely a lighting circuit, intended to operate lights, not outlets. Yes, you will probably have a lamp plugged in, and yes that is a light, but the other half of the outlet could run anything. Best if this outlet is on a circuit intended for outlets, so if there is an option use the power already in the outlet box.

Whether you are installing a completely new outlet or replacing an existing one, the box will contain one or more 2 wire cables with a black, white and ground in addition to the 3 wire cable you have added. Cut a short, 6" piece of additional cable and remove the outer sheath. Splice all of the grounds together, with an additional 6" piece to go to the outlet. Splice all the black wires together with an additional 6" piece of black wire. Splice all the white wires together, again with a 6" additional piece.

Splicing is accomplished by stripping about ½" of insulation from each wire and twisting a wire nut onto the bundle of wires, fastening them all together. Holding the wire nut in one hand, tug firmly on each individual wire to make sure it isn't loose in the wire nut. Pull fairly hard to test the wire nut; better that it come apart now than later.

The ground wire will terminate on the green ground screw of the outlet. The black wire will terminate on one of the brass colored screws, the red wire on the other brass screw and the white wire on the silver colored screw. Most common is to put the red wire on the bottom screw; that will leave the top plug in "hot" at all times and be a little easier to plug things into it. To terminate the wires, strip about ½" of insulation and bend a hook in the wire. Loop it around the screw in a clockwise direction and tighten the screw firmly. If the wire tends to come out from under the screw while tightening, you have looped it the wrong direction. Alternatively, many home grade outlets have small holes in the rear of the outlet where the wires can be simply pushed in instead of wrapping around the screw.

At the switch, put a wire nut on the white wire, capping it off, and tuck it into the back of the box. It will not be used. Splice all ground wires in the box together (if multiple switches or other wires are in the box), again with a "pigtail" to go to the switch. Terminate the ground wire on the green ground screw of the switch.

Terminate the black wire from your new 3 wire cable on one of the screws on the side of the switch, and the red on the other. It doesn't matter which one goes where.

Wiring Diagrams for a Half Hot Switched Outlet

Power is found in the outlet box.  This is the preferred method.
Power is found in the outlet box. This is the preferred method. | Source

Power In The Switch Box

There will again be at least one 2 wire cable plus the new 3 wire cable you have installed. If this is a multiple switch location (more than one switch in one box) there will be other cables, and the cable that is bringing power into the box must be located. This cable will almost certainly have multiple short wires spliced to it, one wire for each switch.

Splice all ground wires together, with a pigtail added. Splice the black power wire and the black wire from the new 3 wire cable together, with a black pigtail added. Splice all neutral wires together, but without a pigtail. The black pigtail will terminate on one of the switch screws and the red wire on the other. The ground pigtail goes to the green ground screw on the switch.

At the outlet box, if there are cables other than the new 3 wire you have added, splice them together by color. Black wires together, white wires together and all ground wires (including the one in the 3 wire cable) together with a pigtail. Neither the existing black or white wires will be used for the outlet, but may be powering other outlets on the circuit if this is not a new outlet.

The ground wire goes to the green ground screw on the outlet, the white wire goes to a silver screw, the black wire to one of the brass screws and the red wire to the other brass screw. All of these wires (except for the ground wire if there are other cables in the box) come only from the new 3 wire cable.

Wiring Diagram For Power In The Switch Box

Power is found in the switch box.  Not the preferred method, but quite acceptable.
Power is found in the switch box. Not the preferred method, but quite acceptable. | Source

Finishing The Job

With the outlet and switch wired, fold the wires back into the boxes as neatly as possible and mount the outlet and switch into the box. Attach the cover plate. If you have any trouble here, additional instructions on changing light switches or installing electrical outlets in general can be found in these links. Tips on removing existing outlets and switches are also in those articles.

Turn the breaker back on and check operation. One half of the outlet should be on at all times, with the wall switch controlling the other half.

© 2012 Dan Harmon

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Comments 25 comments

Sumona Ireen profile image

Sumona Ireen 2 years ago from New York, US

good hub ..............................i like it.

Ed Newbold 14 months ago

Thanks for a clear tutorial. Appreciate it. Also, I've been tracking each of my outlets down to the circuit breaker box very successfully (using a Sperry tool), but one of the circuits (to a basement bathroom that was added years later) does not trace back to the breaker box. That worries me. Do you have any suggestions/comments about this situation?


Ed in Columbus, OH

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

I'm sorry, but not really. However: is there a sub panel anywhere? Does your tool trace a GFI (a bathroom should be on a GFI). Is the receptacle wired reverse polarity? Is it hot?

Failing all else, I would definitely flip breakers until I found that circuit: it is just possible that someone wired it without being on a breaker (removing the panel front, you can check the main breaker for the Sperry signal).

Timc2 14 months ago

Great explanation, thank you. Question, I am wiring a half hot under a sink so I can run a dishwasher and garbage disposal but there's only 3 wires, black, red, and ground in the box. They had a GFI outlet underneath which I am replacing per your comments above. What is the easiest way to get the additional hot line there?

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

If it is a Romex cable it has a white as well. Probably buried back in the box. If it is a conduit, you can pull an additional wire through the conduit. If I'm misunderstanding, let me know.

Timc2 14 months ago

Thank you for the quick response. I mispoke it is black, white and green in the outlet box. No conduit was used near as I can tell. At the switch there is a black wire connected to the top brass screw and a red wire pig tie to the bottom brass screw. They took the ground wire and connected it to a GFI plug which is next to the switch, but there is no ground wire on the switch.

Timc2 14 months ago

In your diagram above it is definitely set up where the power is in the switch box.

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

Let me try again. The outlet has a black, white and green. You want to make it a half will need two colors wires plus a green between the two, but the white in a romex can be colored black or red.

Timc2 14 months ago

Yes, the outlet I want to make half hot has black, white and green. The black is connected on the brass terminal, the white on the silver terminal, and ground to green screw.

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

Then you need 3 wires to the switch, including the green. Are you installing a new switch box and switch?

Timc2 14 months ago

I had not planned on installing a new switch.

The switch box which is located above the counter contains a switch and a GFI outlet. The switch has a black wire on the top screw, and then a red wire on the bottom screw which is pigtailed to the power. There is no ground wire on the switch.

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

But what is that switch doing? What does it operate? Is it running the outlet you want to be a half hot? That will require getting another wire to the outlet box for a hour that is not switched.

Timc2 14 months ago

The switch runs the outlet underneath the sink that I want to make half hot.

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

Finally got it. Yes, you will have to hat another wire to than outlet from the switch. All you have now is a switched wrote and you need a permanent hot.

Timc2 14 months ago

Thank you very much this was very helpful.

wilderness profile image

wilderness 14 months ago from Boise, Idaho Author

Hope it helps you out. Good luck with your project!

Linda Robinson60 profile image

Linda Robinson60 11 months ago from Cicero, New York

Hello Dan what a tremendous hub, so much essential information that is so perfectly worded making it very understandable, detailed and interesting. So nice meeting you.

Jennifer 7 months ago

I'm trying to make an existing outlet half hot. I noticed the current outlet only has one red and one white wire. How can I make this outlet half hot with only two wires?

wilderness profile image

wilderness 7 months ago from Boise, Idaho Author

It will require a new wire to be installed. It sounds like the outlet is already switched: if so you will need a new wire from the switch to the plug. Or, possibly, from another outlet on the same circuit, but care must be taken to assure it IS the same circuit.

If it is not switched already, then a wire from the outlet to a switch is required.

But are you positive there isn't a black wire already in the box, perhaps tucked back where it can't be seen without removing the outlet from the box? While it is possible, it would be unusual to find a red wire in a residential outlet box without a black wire also being there, and it is typically that black wire that is hot all the time.

BarbaraGeraghty 5 months ago

Hi Dan,

Can you provide an estimate for the following. I think my plumber is taking advantage of me.

three wire romex needs to be run between the switch box and under sink receptacle box.

wilderness profile image

wilderness 5 months ago from Boise, Idaho Author

I'm sorry, but no. There are far too many variables to try and give an estimate of costs. From labor costs in your area to distance from the switch box (panel box?) to ampacity of the circuit and others as well.

Brad 4 months ago

How would you control an entire GFCI receptacle with a switch? My understanding is that a neutral is required in newly installed switch boxes so I cannot do a switch loop. Thank you.

wilderness profile image

wilderness 4 months ago from Boise, Idaho Author

If the power is in the switch box, use a 2 wire cable. The power black to the switch, and black on the two wire cable to the GFI where the black would normally go. Neutral splices in the switch box without terminating on the switch at all.

If the power is in the receptacle box, use a 3 wire cable between receptacle box and switch box. Black splices without terminating on the GFI, and goes to the switch. Red goes on the GFI where the black would normally go and the other end to the switch. Neutral splices in the receptacle box, plus terminating on the GFI, and the other end simply ends in the switch box. In this manner, the power must go from the receptacle box to the switch, through the switch and return to the receptacle box and GFI.

Nicholas Hodge 11 days ago

Similar as you've answered before, but maybe a little different. I've just installed 20A outdoor gfci plug (switched from above counter) and want to plug dishwasher and disposal to it. Can I remove wall switch and attach corresponding wired with wirenuts and a half solid wallplate, or leave switch as is in on position and install sink mounted push button for disposal? This would be very helpful. Thank you in advance!

wilderness profile image

wilderness 11 days ago from Boise, Idaho Author

Hi Nicholas. What you describe, a GFI to operate both a dishwasher and a disposal, will not work as there is no way to switch only half of the GFI. The switch would have to be on any time the dishwasher is running.

To make this work you will have to install a second outlet next to the GFI, using the "load" contacts on the GFI to power it, for the disposal. That way the second outlet can be switched while leaving the GFI on at all times.

I might also be possible to install a single duplex outlet, powering it from the "load" side of a GFI elsewhere in the room. You could then switch just half the outlet while retaining the protection of a GFI.

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