How to ground an old style electrical outlet box...Part 1

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How to Ground an Outlet

Three Parts:

Older homes often have two-pronged receptacles (sometimes referred to as outlets) that should be replaced with a Ground Fault Circuit Interrupter (GFI or GFCI) receptacle. Some newer houses may likewise have a receptacle that was not grounded properly or the ground wire may have become loose or disconnected. Doing this yourself can help save you from hiring an expensive electrician, and it's a relatively simple procedure with the right preparation and know-how.


Getting Started

  1. Check your local electrical codes and schedule inspections.Several inspections and permits are required for most residential construction projects, especially when it involves electrical work.To make sure you're up to code, you may need to schedule temporary service inspection, a rough-in inspection, and a final inspection. This needs to be done whether you're doing it yourself or hiring an electrician.
    • Depending on where you live, you may be able to do the inspection yourself if you live in a single-family home.
    • The National Electrical Code requires all GFCIs within 5 feet of the floor to be tamper resistant and clearly marked. Outdoor GFCIs must also be weather resistant and clearly marked with the letters "WR," even if it has a weather cover. In some areas, you may need a GFCI due to nearby water fixtures.
    • Check your local wiring codes to see if a three-prong GFCI is an acceptable replacement for a non-grounded two-prong receptacle. There are acceptable installation procedures for a non-grounded GFCI, usually involving putting a sticker on the receptacle cover stating "No Equipment Ground." The GFCI does not, itself, require any ground connection for proper operation.
    • If your home was wired "to code" initially, there is generally no legal requirement to upgrade to grounded outlets or GFCI (or even AFCI) outlets unless other work is being done that exposes the wiring. Insurance or other safety concerns may, however, outweigh meeting only the minimum code requirements.
  2. Purchase a circuit tester at a local home repair store.A circuit tester plugs into the receptacle and has several light combinations to indicate the different problems a receptacle may have. If you're going to ground a receptacle, it's an important tool to have. You can purchase these at any home repair store. One model has a button to test GFCI receptacles. It's a little more money but a better buy to verify the GFCI is also grounded.
  3. Test the receptacles in your home.Plug the circuit tester into each receptacle and look at the indicator lights. If the lights indicate the receptacle is not grounded properly, mark the cover with a piece of masking tape. Move on to the next receptacle.
    • Most such testers are designed with three prongs: hot, neutral and ground. If your receptacle has only two prongs, you would need a different type of tester or attachment to determine whether a ground reference is present, i.e., a voltage indicated between hot and a grounded box or metallic conduit or cable sheath.
    • Make sure your circuit tester is working before you start by plugging it into a receptacle that you know works.
    • Do not try to fix more than one receptacle at a time. Unless you are sure of your work, it's better to check them one at a time. This may involve turning the electrical circuit breaker on and off many times while you work.
  4. Turn off the power at the main electrical box.Either turn off the circuit breaker that controls the receptacles to the specific room or turn off the main switch for the whole house. If you only turn off the breaker, retest the receptacle with the circuit tester to ensure it's the correct one.
    • Some "circuit identifier" devices automatically confirm you have switched off the proper circuit because the "tone" unit plugged into the receptacle stops signaling when its circuit is off.
    • Be aware that some duplex (double) receptacles may be internally "split" so that one part is switched separately from the other, such as for floor lamps. You may find a receptacle is still "hot" in one and not in the other, if the switch is off but the breaker is still on. You should test BOTH outlets of a duplex receptacle unless you already know how it's wired, i.e., after you open the box and pull it out.
  5. Remove the cover plate of the receptacle.For the most part, cover plates will be attached with flathead screws, which means you should be able to easily remove them with a small, flathead screwdriver. If paint or wallpaper is in the way slightly, you might need to carefully cut around the receptacle with a utility knife to keep the wallpaper from tearing and making the wall look raggedy.

Examining the Receptacle

  1. Remove the receptacle.Unscrew the mounting screws located at the top and bottom of the receptacle. You may need to cut the painted edge or plaster and pry it loose. Carefully ull out the receptacle from the box as far as the wires allow and locate the green grounding screw near the bottom of the receptacle.
    • Locate the grounding wire, if applicable. Oftentimes, the grounding wire is bare copper. The grounding wire may also be green if it comes from a factory-assembled device. A metal box might also be grounded via conduit or metal-sheathed cable.
  2. Examine the receptacle and the wiring.If you have three wires in the box (black, white, and copper), you will need to attach or tighten the grounding wire. If you have only two wires and a 2-prong receptacle, you can attach a GFI or GFCI receptacle.
    • This provides ground fault circuit interruption to the branch circuit and must be identified as "no equipment ground." If your older wiring only has two wires (black and white, with no grounding wire), the box is not grounded and you will have to replace the cable with the right number of conductors, including a black, white, and grounding wire, if you desire grounding (e.g., for reducing radio-frequency noise).
    • In the United States, no separate ground wire may be run to an existing receptacle to provide a Ground for a GFCI receptacle, because it's a violation of the electrical code.
    • If you have a ground wire, usually a bare copper or green wire, in a cable or conduit arriving in the box, it may or may not be grounded, which means you should test that for ground. If you have one of those, you can hook it up to a grounded receptacle and use an ohms meter to see if it’s properly bonded to ground.
    • Metal conduit and many types of metal-sheathed cables also serve as proper grounding means, provided they have an unbroken "path" bonded to a proper grounding point.
    • If you find very old wiring (black cloth around rubber-coated wiring), you may have to leave it alone and call an electrician to replace it properly. Simply moving it may have permanently damaged the insulation, making it unsafe to energize.
  3. Secure the ground wire.Often the grounding wire is wrapped around the cable as it enters the box. In this case you should pigtail all of the device grounds together and have one lead from the pigtail ground to the metal device fixture box.
  4. Install a new receptacle if necessary.If you don’t have a grounding conductor in the box, and you need an actual ground reference there, grounding that receptacle would require installing new wiring to code. Grounding a three-prong GFCI replacement for a two-prong receptacle is not always necessary.
    • If you are going to use a GFCI to protect and control additional receptacles, with or without ground, you can use the cable and conductors that runs to other receptacles that are in line (down the chain) from that GFCI. One GFCI will protect all of them, if properly connected as "load" on the first GFCI.
    • The load terminals on the GFCI are only used if you’re trying to protect other receptacles with that GFCI. There are two terminals on the receptacle that are normally used: hot and neutral. The ground terminal is not actually used by the GFCI but must be marked "No equipment ground" on each protected receptacle if it is not connected to a grounding conductor.

Grounding the Receptacle

  1. Attach the grounding wire to the grounding terminal.If the grounding wire has become loose or disconnected, loop the grounding wire over the green terminal screw and tighten with a Philips or flathead screwdriver. Make a loop at the end of the copper wire with a pair of needle-nose pliers. This secures the wire onto the screw. Be sure to place the loop of the wire on the terminal screw so that when you tighten the screw, the loop is tightened and not pushed off the terminal.
    • On a GFCI receptacle you would connect to the two "Line" terminals. Only the downstream receptacles would be connected to the "load" terminals of a GFCI.
    • Check the connection of the other wires as well. The black wire should be securely fastened to the brass terminal, which is marked "Hot," and the white wire to the silver terminal, which is labeled "Neutral." On a polarized receptacle, or a grounded receptacle, the larger slot is neutral (white wire) and the smaller slot is hot (black wire).

#*While you're there, make sure any other connections in the box are tight, including wire nuts holding all wires securely, tucked out of the way, and any clips or screws are tight.

  1. Secure the receptacle.Wrap the receptacle with electrical tape, covering the terminals, and push the receptacle back into the box, folding the wires carefully and making sure the bare copper wire is not near the "hot" terminals. Tighten with the mounting screws. Replace the cover plate and tighten securely, but not hard enough to crack the plastic.
  2. Turn the power back on.Retest with the circuit tester to be sure you now have a correctly grounded receptacle. If it is a GFCI receptacle, press the reset button. Plug in a device, switch it on, press the test button on the receptacle (shutting off the device) and then the reset button (turning it back on), to confirm its correct operation.
    • If you have provided a ground to the receptacle, you may also use your external tester with a GFCI test button to test the GFCI function.
    • Note that most external GFCI testers (i.e., 3-prong plug-in with its own GFCI "test" button) will NOT trip an ungrounded GFCI, but the internal GFCI test circuit in a receptacle will verify that the basic function works, even with no ground connected to it. A more sophisticated tester with an additional grounding wire of its own would make a better test in such circumstances.

Community Q&A

  • Question
    How do I ground a wire for a ceiling fan?

    Licensed Electrician
    Ronny Husser is a Licensed Electrician in Maine. He is a certified member of the National Association of Home Inspectors who has been doing Residential Home Electrical Services since 1984.
    Licensed Electrician
    Expert Answer
    You would use the ground wire from the feeder cable. If no ground wire is available in the feeder cable, it will have to be replaced with one that does.
  • Question
    How do I ground a new GFI plug if there is no ground wire?

    Licensed Electrician
    Ronny Husser is a Licensed Electrician in Maine. He is a certified member of the National Association of Home Inspectors who has been doing Residential Home Electrical Services since 1984.
    Licensed Electrician
    Expert Answer
    In order to ground a new GFI plug, the feeder cable must supply a grounding conductor.
  • Question
    If I have a standard 3-wire and metal outlet box, should I attach the ground from the line to the box with a screw before attaching it to the outlet? If so, why?

    Licensed Electrician
    Ronny Husser is a Licensed Electrician in Maine. He is a certified member of the National Association of Home Inspectors who has been doing Residential Home Electrical Services since 1984.
    Licensed Electrician
    Expert Answer
    Yes, if the device box is metal it must be grounded by code. This is done for safety reasons to ensure a proper path for a ground fault to follow.
  • Question
    I am interested in replacing an old two prong outlet with a three prong. In an older outlet with no ground wire evident inside the box, is there a way to check whether the grounding wire is attached to the cable outside the box without cutting a hole in the wall?
    wikiHow Contributor
    Community Answer
    If the Box is metal, yes there is. If you have the outlet pulled out of the junction box, you can take a electrical tester and touch one prob on the black (hot) wire and use the other prob of the tester and touch the inside of the metal box. If the tester lights up or if using a meter it reports back Voltage, then it is more than likely grounded. When you wire up the new outlet, make sure to wire up the ground wire to the metal Junction box.
  • Question
    Can a grounded wire consume more power?
    wikiHow Contributor
    Community Answer
    Not unless there is an electrical problem. If this is the case, the grounded wire is doing exactly what it should do--directing current away from the device.
  • Question
    I ran a ground wire for an outlet but when I test it no ground is indicated. What does this mean?
    wikiHow Contributor
    Community Answer
    It means it isn't grounded. Make sure that your grounding wire (and whatever the other end of it is connected to) has a complete uninterrupted path into the Earth.
  • Question
    Is it all right to ground the outlet to the metal box for an older outlet box that doesn't have a ground wire in the box?
    wikiHow Contributor
    Community Answer
    Generally, NO. Without a ground wire attached to the box, attaching a ground wire from the outlet to the box is useless. It would only be acceptable if the box were connected to the building ground through metal conduit. To ensure that the conduit is properly connected, a ground bond test should be performed. This test applies a large amount of current (more than 20 A) to the ground path to ensure that it will not cause any fires and will trip any safety devices.
  • Question
    Why does power go on or off in the outlets, but doesn't blow the circuit breaker?
    wikiHow Contributor
    Community Answer
    This may be caused by a loose neutral wire. This is extremely dangerous, and should be corrected by an electrician immediately.
  • Question
    How do I ground a plastic electrical box?
    wikiHow Contributor
    Community Answer
    You don't. The outlet or switch inside should have a ground wire that connects to the building ground.
  • Question
    Can the added ground wire be attached to a copper pipe under the sink?
    wikiHow Contributor
    Community Answer
    No. Run the ground wire to a ground rod that is buried 8 feet deep. Clamp the ground wire with a quality clamp.
Unanswered Questions
  • Is it required by electric code in Canada (or other Canadian regulations) to have electric outlets grounded in homes?
  • How do I ground a wire with power at a plug?
  • What could be the possible cause when an electric fan stops? The electric fan is slow turning, branch circuit breakers always trip, motor is very noisy and hums, AC motor on voltage even CB ON, AC plug sparking.
  • How do I ground an outlet?
  • I'm building a campervan. Is it OK to use metal boxes with GFI outlets that are attached to the van metal ribbing? Any safety concerns?
Ask a Question
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Quick Summary

Before you attempt to ground an outlet yourself, check your local electrical codes and schedule any required inspections. Turn off the breakers to those outlets and remove the screws attaching the cover plate over the outlet. Next, unscrew the mounting screws located at the top and bottom of the receptacle and pull it out. If you have 3 wires in the box, you will need to attach or tighten the copper or green grounding wire to the green grounding screw. If you have only 2 wires and a 2-prong receptacle, you can attach a GFI or GFCI receptacle.

Did this summary help you?


  • Over tightening the screw in the cover plate can cause the cover plate to crack.
  • When tightening the mounting screws, be sure the receptacle is straight.
  • Do not over tighten the terminals when connecting the wires. If you do, and you hear something snap in the receptacle, remove and discard the receptacle.

Things You'll Need

  • Circuit tester
  • Flat head screwdriver
    1. 2 Philips screwdriver
  • Electrical tape
  • Needle-nose pliers
  • GFCI receptacle (as needed). If the new GFCI didn't come with a new cover plate you may need one.

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Date: 02.12.2018, 01:16 / Views: 42261