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An Electrician Explains How to Wire a Switched (Half-Hot) Outlet

Dan has been a licensed journey-level electrician for 17 years. He has extensive experience in most areas of the electrical trade.

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 permanently "on," or ready to provide electricity, while the other half can be turned off and on via an ordinary wall switch.

While the entire duplex outlet could be turned on via a wall switch, only one of the two plug-ins is usually switched; this leaves the other half permanently powered for other uses.

This kind of outlet is quite common in modern construction. If you plug a lamp into the switched side, you can turn the light off and on via the wall switch. Half-hot outlets are most frequently found in living rooms, but they can be put into any location.

Learning how to wire a switched outlet is not difficult. It is similar to wiring a regular light fixture. Find out how below.

Note: 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.

A half-hot (or switched) outlet is a double outlet that has one half permanently on (ready to provide electricity) while the other half can be turned on and off via an ordinary wall switch.

Preparing the Switched Outlet for Wiring

  1. If you are modifying an existing outlet, it is almost certain that the old outlet won't need to be replaced, although if it is more than a few years old, it should probably be replaced anyway.
  2. Either the square, Decora-style switch, or the more common semi-round type may be used as a half-hot outlet. You may not, however, use a GFI outlet (it is not possible to modify one so that only half of it is switched), but the entire outlet could be switched.
  3. If you are purchasing a new outlet, make sure that you match the outlet's 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.
  4. After you've taken off the faceplate, on the side of the outlet there is a small tab connecting the two brass screw-plates together. This tab allows one wire to be used to power both halves. This tab has a slot in it so a small screwdriver can be inserted to break it off. To modify the outlet for use as half-hot, use a screwdriver or a pair of needle-nose pliers to twist and break that small connecting tab. Break only the tab on the side with the brass-colored screws; the one connecting the two silver screws needs to remain intact. See photos for details.
  5. With the tab broken, the outlet is ready for use.

What Kind of Wiring Do You Need for a Switched Outlet?

  • The National Electric Code requires that all lighting switch boxes contain a "neutral," which is an electrical term for a grounded conductor (not to be confused with a ground wire). In your outlet, it is the white wire that terminates on the outlet. Whether or not a half-hot outlet is for lighting is debatable, but you must still have a neutral in the switch box.
  • There are two possibilities for the location of the incoming power: either in the outlet box or in the switch box. Either way, you will need what is called a "3-wire cable" (black, red, white, and green OR metal all sheathed together—yes, I know that makes 4 wires, but that's what it's called!) to connect the two boxes.
  • 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.
  • The Romex (NMC) wire you will be using is generally available in 25', 50', 100', and 250' rolls.
  • Make sure you purchase enough wire, as the job will usually require more than you think. To be safe, add about 20% to your best estimate.
home-wiring-guide-how-to-wire-a-switched-half-hot-outlet

There Are 4 Wires in a Romex 3-Wire Cable! What Do the Colors of the Wires Indicate?

  • White: the neutral. See warning below!
  • Green or bare copper without insulation: the ground wire.
  • Red: hot.
  • Black: hot.

These will all be cabled together in a sheath. Romex wire is usually used in houses.

The White Wire: A Word of Caution

Switch boxes in older homes usually used the white wire as a power wire, not a neutral. So when the white wires in a switch box are spliced together, any that go to a switch should be ignored and left right where they are.

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Do not splice those white wires already on a switch to any other white wires, and especially not to the new white wire that is a part of your new 3-wire cable.

It wasn't until 2011 that the National Electric Code ruled that a white wire being used as a neutral was required in the switch box. Prior to that, it was acceptable to use the white as the switched "hot" wire, although a conscientious electrician would color it to something else (using magic marker, black tape, etc.).

So if you are replacing an older, existing switched outlet, and if it has 2-wire cable between the outlet and the switch, then the white wire is being used as either a permanent hot or as the switched power and IS NOT neutral. Care must be taken to keep it separate from other white wires.

How to Wire a Half-Hot Switched Outlet

Before you do anything, TURN OFF THE POWER! A non-contact voltage detector can be invaluable here for detecting power through the insulation of the wire. Make sure that the power is off. A nasty shock is the least 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 below.

How to Wire a Switched Half-Hot Outlet That Gets Its Power From the Outlet Box

This is the preferred method of wiring a half-hot switched outlet because if the power is coming from the switch, it is most likely a lighting circuit that is intended to operate lights, not outlets. Yes, you will probably have a lamp plugged in, but the other half of the outlet could run anything. It is 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.

  1. In order for the outlet box to work, it must already contain one or more cables made up of black, white, and green/bare ground wires all cabled together. In order to add the switch, you will be adding a Romex 3-wire cable to the box.
  2. Cut a short 6" piece of cable and remove the outer sheath. This gives you four different colored wires to splice in with the matching wires in the box. These 6" pieces (or "pigtails") will attach to the outlet. Strip off the last 1/2 inch of colored plastic coating on each end of each wire.
  3. Next, you will splice all of the grounds (green or bare wires) together with that additional green/bare 6" piece. Splicing is when you twist all the bare metal wires together so that they're in contact. You should pull them into a neat bundle with the stripped ends all together, twist them into one, put a plastic twist-on wire nut over them, and screw it down tightly as if it were a bolt head. Hold the wire nut in one hand and tug firmly on each individual wire to make sure it doesn't come loose. Pull fairly hard to test the connection; better that it comes apart now than later.
  4. Do the same with all the black wires (and the additional 6" piece of black wire you cut in step 2).
  5. Splice all the white wires together, again with the 6" additional white piece.
  6. The loose end of the 6" ground wire will terminate on the green ground screw of the outlet. The black 6" wire will terminate on one of the brass-colored screws, the red one on the other brass screw, and the white one on the silver-colored screw. It is most common to put the red wire on the bottom screw, since that will make the top plug-in "hot" at all times and will be a little easier to plug things into it.
  7. To terminate (affix or connect) the wires, 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.
  8. 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 an additional 6" green/bare piece to go to the switch. Terminate the ground wire on the green ground screw of the switch.
  9. 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.
Diagram for a half-hot switched outlet that gets power in the outlet box (the preferred method).

Diagram for a half-hot switched outlet that gets power in the outlet box (the preferred method).

How to Splice Electrical Wire (the Electrical Tape Is Optional):

How to Wire a Switched Outlet That Gets Its Power From the Switch Box

  1. First, locate the cable that is bringing power into the box. You will see at least one 2-wire cable and the added Romex 3-wire cable that you're connecting to the outlet. If this is a multiple switch location (with more than one switch in the box), there will be other cables, too. The power cable will almost certainly have multiple short wires spliced to it, one wire for each switch.
  2. Cut a short 6" piece of cable and remove the outer sheath. This gives you four different colored wires to splice in with the matching wires in the box. Strip off the last 1/2 inch of colored plastic coating on each end of each of these 6" pieces (or "pigtails").
  3. Splice all the ground wires together, with an extra 6" pigtail piece of ground wire added.
  4. Splice the black power wire and the new black wire from the new 3-wire cable together, with a black pigtail added.
  5. 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.
  6. The ground pigtail goes to the green ground screw on the switch.
  7. At the outlet box, if there are cables other than the new 3-wire you are using to connect the outlet to the switch, splice them together by color: Black wires together, white wires together, and all ground wires (including the one in the 3-wire cable) together, all with like-colored pigtails.
  8. At the outlet box, 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.
  9. 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 (not the preferred method, but acceptable).

Wiring diagram for power in the switch box (not the preferred method, but acceptable).

Finishing the Job

  1. After wiring the outlet and switch, fold the wires back into the boxes as neatly as possible and mount the outlet and switch into the box.
  2. Attach the cover plates.
  3. If you have any trouble here, additional instructions on changing light switches or installing electrical outlets can be found in these links. You'll also find tips on removing existing outlets and switches in these articles.
  4. 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.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: I have a garbage disposal that is plugged into an outlet under my sink. That outlet is connected to a GFCI outlet. The disposal is turned on by hitting the button on the GFCI. I want to change that so a separate switch will power the disposal. Any suggestions?

Answer: First, remove the GFCI and the box that it is in. Open the hole, and install a 2-gang box in the place of the one removed. Re-install the GFCI, but do not connect the wiring to the outlet under the sink. Instead, splice the neutrals from the feed to the GFCI and the under-sink outlet together, splice a short jumper to the black feed to the GFCI, and connect that jumper to a new switch. Add the black wire to the under-sink outlet to the switch, install it in the new two gang box, alongside the GFCI, and put a new cover plate on.

This will remove the GFCI protection from the disposal outlet, which is acceptable in most parts of the country. If you would rather keep that protection, install the neutrals just as they were, put a jumper between the GFCI (where the undersink black wire used to be) and the new switch, then put the undersink black to the switch.

As it is, the undersink is powered all the time; as long as the GFCI is not tripped. You are using the test button on the GFCI to turn it (and the under-sink outlet) on and off; adding a switch will eliminate that.

The article at https://dengarden.com/home-improvement/adding-elec... will give some hints on how to remove and replace the existing box - you won't need to run new wire but do need a different box than what is there.

Question: Can you put a USB outlet with the top always on and the bottom on a switch?

Answer: Assuming you mean outlets that include a USB port or two along with the normal two outlets, it would depend on the manufacturer. If there are two brass screws for the black wire, and a breakable tab between them, it might be possible. You would have to break that tab and wire first the top, then the bottom, checking each time to see if the USB ports are hot. If they are hot with the top wired, but not the bottom, then you can probably wire the outlet as a half hot. If they are hot both ways, it is likely that the screws are connected internally, and you cannot switch just half of the outlet.

Question: I have power coming to a receptacle. It's a half and half with the top half controlled by a switch. At the switch, the neutral is capped off. I want to put a switch next to it to run to my porch light. Do I have to run a separate feed line, or can I go off get power off of the existing switch that's there?

Answer: If there is a capped off neutral in the switch box, you can put in a second switch for another light, just as you want to do. You will have to figure out which of the existing switch wires is permanent, and hot and splice into that wire to supply the new switch.

Question: I have a plug in the outlet on one side of the room that if you turn on the microwave on the other side, that is plugged into the other outlet it all goes off but if you hold the one plug in a certain way, it will all work. So I need to know why and how to fix the electric to all plug in. Do you have any idea how or why it's operating that way?

Answer: It sounds like a bad outlet, from the information here. I'd replace one or both of the outlets and see if that helps. Outlets are cheap and easy to replace.

Question: I installed a ceiling light and have it powered from the switch that powers an outlet in same room. Is it possible to isolate the outlet from the switch so only the light is controlled by the switch without running new power from/to the panel?

Answer: Maybe. If the outlet is a half-hot (only half the outlet is switched) the fix is easy. Just install a new outlet, using only the permanent hot in the box and cap off the switched wire with a wire nut.

If it is not a half hot, you may still be able to do it, depending on how the wiring is run. Remove the outlet and look in the box - is there an extra (probably black) wire or wires that is not connected to the outlet? If so, these are almost certainly the hot wires for that circuit: remove the wires from the brass terminal, cap them off, and put the other wires (that were not connected) in its place.

If there are no other wires, check the switch box. If the switch has a wire going only to the outlet (and a separate one to the light fixture) it can be connected to the permanent hot in the switch box rather than the switch. In most cases, the permanent hot can be located and used to power the outlet rather than the switched wire.

Question: My ceiling light is not working. I tested the wiring at the switch. I used the tester on black and white, and shows no power. When putting the tester on black and ground, it shows power. What could be wrong?

Answer: If at the switch, you have power between black and ground but none between black and neutral the most probable answer is a disconnected white neutral somewhere.

This assumes that the white is actually a neutral, not a switched power - if the white is hooked to the switch then it is not neutral. If the white is on the switch, try between the white and ground, flipping the switch both ways to check.

Question: I replaced my old half hot switch with a new one. I snipped the tab between the brass screws. Both outlets are still hot, and the switch doesn't control either of the two outlets. Two white wires on silver side and on brass side red top and black on the bottom. I also replaced the switch and wired same as an old switch. What could be wrong? One more thing is the switch controlled two outlets but I only snipped one outlet so must I also snip the other outlet?

Answer: Yes, you must also snip the tab on the second outlet. Leaving it in place means that the hot wire and the switched wire are connected; the switched wire will gather power from the hot wire and both will then become hot whether on that outlet or on a different one.

Question: I just bought a house where in all of the bedrooms all the outlets are half-hot to the wall switch. This seems overkill, and I would prefer only one in each room be half-hot. How can this be done?

Answer: Not too difficult, but it will take a little time. First, figure out which half is permanently hot - I'll assume for discussion sake it is the top half.

With the breaker off, remove the outlet from the box. Remove the switched wire and cap it with a wire nut, folding it neatly back into the box. Remove the top black wire and splice it to two 6" jumper wires. Put one jumper on each of the brass screws, where the hot and switched wires used to be.

Alternatively, all the outlets could be replaced with new ones, wiring each one with only the hot wire - the switched hot is capped off as before with a wire nut and folded back into the box.

Question: I have room switches that seem to go "nowhere." How do I detect where they go to or turn on?

Answer: Trial and error is about all you can do. Keep flipping them until you can find something happening. One possibility is that it is going outside, and maybe to something that isn't there. I had a house once that had switches intended for future yard lights and simply ended up in the crawl space under the house.

Question: I have a receptacle in which the top plug is controlled by a light switch. I am installing a ceiling fan in the room and want the top plug to be hot at all times and use the switch only for the ceiling fan. Can I do so by simply buying a new receptacle, and not breaking the brass tab?

Answer: Yes you can. When you wire the new outlet only hook up the "hot" wire to the outlet, not the switched wire. Just put a wire nut on the switched wire to cap it off and tuck it back into the box.

Alternatively, you can splice two pigtails to the "hot wire" at the outlet and terminate one on each of the brass terminals so that each half of the outlet is using the same source of power.

Question: I have a half hot receptacle with the bottom switched and the top always hot. I want to change which one is switched. Is switching the hot wire in a half-hot outlet as simple as swapping the black wires on the brass screws?

Answer: Yes. Just switch out the two wires on the brass screws.

Question: I have a dual outlet box that is switched (both outlets are hot when switched on). I would like to double the box to a four outlet box, two switched and two hot all the time. How do I wire that?

Answer: Assuming that you mean both halves of a single, duplex, outlet are switched the first step is going to be to get a source of permanent hot to the box. You are basically going to install a new, larger, box and add an outlet to it, and that means you will need a source of power for the new outlet.

Question: I have a switch that is controlled by an outlet. I replaced the outlet with a different color. Now when I use the switch the outlet stays powered. I have snipped the connectors between the 2 brass screws. I have 2 red wires in the top and 2 black wires in the bottom. One of the screw and one in the hole on the back. What did I do wrong?

Answer: Somewhere you have connected a switched wire with an unswitched wire. I suggest you check each wire for power with the switch on and then off. If necessary, remove all the wires but one, check the outlet for power, and then use a different wire. Any and all wires that are unswitched must be together, and any wires that are switched must be together.

Question: I have 4 outlets in our bedroom running off a switch. Reading back, I see your advice is to run pigtails off the reds, blacks and white wires with the tab on the brass side broke off and the red wires attached at bottom brass screw? I know you answered this on the single outlet, I'm making sure this how it's done on multiple outlets running off of one switch.

Answer: Assuming that the outlets are daisy chained - that is one outlet to another to another, etc. - you would need two whites, two blacks and two reds on each outlet but the last one. There isn't room for that, so pigtails are necessary. And yes, each outlet you wish to be switched will need the tab broken off. If you do NOT wish an outlet to be switched, simply leave the switched wire (probably red) off and do not break the tab.