I want to replace a standard 120v outlet. It has a copper ground, and on the left side a white wire to the top silver screw, and on the right side 2 black wires (one to each brass screw). My new outlet (duplex receptacle and 2 USB charging points) only has a ground screw, a silver terminal screw, and a brass terminal screw. Where do I attach the extra black wire?

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  • 2
    Please Edit your question and add a pic or 2 of your existing wiring.
    – brhans
    Sep 29, 2022 at 1:06
  • 1
    One problem is that most circuits have one black with/paired with one white. On the side with the blacks, is the tab connecting the two screws there or broken off? Two blacks and one white is usually not good.
    – crip659
    Sep 29, 2022 at 1:06
  • 4
    I just want to confirm what you're saying because it's a bit unusual. You have a single outlet split in two, which we can see because the little tab is removed on the hot (black) side, and there are two hot wires connected. Both parts can be turned off by a single breaker with a single handle, and neither part is controlled by a switch. What you have is normal for a switched receptacle but not for an unswitched one. Are there any switches in the same room that don't seem to control anything? While we're at it, which room of the house is this receptacle in?
    – trawson
    Sep 29, 2022 at 2:42
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    I would suggest that you NOT replace this with a USB charging outlet. Power demands for devices has been rapidly increasing, and this outlet may power the devices you have now, but not the ones you have next year. The wall wart that comes with next year's device will plug into any standard 120v outlet for decades to come and will provide the necessary power. You'll be "upgrading" your USB receptacles every year or two trying to keep up...
    – FreeMan
    Sep 29, 2022 at 12:37
  • 3
    @user253751 the wall wart will come with the device and provide whatever power the device needs. A USB outlet from 3-5 years ago would only provide 500-1000mA which wouldn't even come close to charging many new devices today. Also, form factor changes. A USB-C cable won't fit into a USB 1/2/3 port, but it'll fit into the port on the wart included with the device.
    – FreeMan
    Sep 29, 2022 at 17:35

2 Answers 2


If you look at the silver screw side of the receptacle you'll see a small metal tab in the notch near the face of the receptacle that joins the two screw baseplates. That tab has been broken off on the brass screw side shown in you picture in order to separate the two halves of the receptacle into separate circuits. The typical application is to control one half of the outlet with a switch while the other half is always live. (Both halves might be switched independently.)

You have a choice of making the new outlet always on or switched, simply pick the appropriate black wire to supply power and insulate the remaining black wire with a suitable wire nut.

  • 2
    The catch is that if the switch controlling the half-receptacle does not control anything else then you have removed the required switched light capability. So that needs to be figured out first. Sep 29, 2022 at 1:54
  • I would like to make my new outlet "always on" (no other option with only a silver and a brass screw). I can find no switch that controls either half of the existing outlet, both have power to them. What is the best way to determine which black wire to use?
    – Lenae
    Sep 29, 2022 at 2:01
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    @manassehkatz-Moving2Codidact true if there are no permanent lighting fixtures installed. But if there are switched ceiling lights or similar then you don't have to have a switched receptacle.
    – trawson
    Sep 29, 2022 at 2:44

It is probably switched outlet.

A switch will control one of the plugs.

You have the option of leaving it as is (switchable outlet) by breaking up the small connector on the side of the plugs and connect the two blacks to each of the screws, while keeping the white on the other side.

You can also connect one white and one black and cap off the other black or connect the 2 blacks under one screw.

  • 3
    I don't need a switched outlet there (I have no extra switches, so not sure where it would be controlled). Also, with my new outlet I can't keep it wired the same - I only have one silver screw and one brass screw (and the ground screw of course).
    – Lenae
    Sep 29, 2022 at 1:40

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