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How To: Fix Ungrounded Outlets

A common problem found in old houses is the presence of ungrounded outlets. Either you’re stuck with old fashioned 2-prong outlets that won’t fit your 3-prong devices, or someone replaced the old outlets with 3-pronged outlets that don’t have a ground wire.

how to fix ungrounded outletsThe 3-pronged outlets are often a sheep in wolf’s clothing since they look like modern outlets, but don’t have any of the protections.

Important Disclaimer: While I am a licensed contractor, I AM NOT a licensed electrician. So, before you put any of this information to use, check with a local electrician first. Electrical work is nothing to take lightly as you can cause fires or electrocution. Don’t do any of this work if you’re not qualified.

Since the early 1960s, most electrical codes have required a ground wire to be run to all outlets and appliances, but prior to that time, most wiring was just 2 wires (hot and neutral).

The ground wire provides an alternate path for electricity that may stray from an appliance or product to make its way safely back to the breaker or fuse box and exit the building into the main ground connection.

Electricity is like water in that it always chooses the path of least resistance. Without a grounded outlet, that path is either through your appliance which will fry your TV, computer, microwave, etc. or in the worst case, through you! You may think that having a surge protector is enough, but surge protectors only work properly when attached to a grounded outlet.

There are two possible ways to fix the issue of ungrounded outlets and I’ll walk you through both of them.

How To Fix an Ungrounded Outlet

The ideal way to repair an ungrounded 3-prong outlet is to establish a continuous electrical path back to the main panel.  If the outlet is installed in a metal box and that metal box has metal conduit wiring (BX cable) all the way back to the panel, then you can ground your outlet with just a little work.

To make sure you have the right setup, you can use an inexpensive pig-tail electrical tester. With the circuit energized, touch one end of the tester to the hot wire (the smaller slot on the outlet) and one end of the tester to the electrical box. If the tester lights up, the box is grounded. If you get no light, then there is no ground and this method won’t work for you. Skip down to Option #2 below.

If the tester lit up, then all you need to do is run a bare copper wire from the ground screw on the outlet and attach it to the metal box. This will provide a ground using the equipment already in your house.

If your outlets are installed in a concrete wall, there is a possibility of getting a false reading, but for wood frame structures, this is a good test. If you are dealing with concrete walls, call an electrician to check things out or try Option #2.

 

Option #2 Install a GFCI

So, your house doesn’t have metal cable and you can’t get a grounded outlet that way. All is not lost. There is another option that is not quite as good as an equipment ground but will keep you safe just the same.

You can swap out your standard outlet for a GFCI outlet on any ungrounded outlets to provide protection from shocks and surges; however, you will need to add a sticker to the GFCI outlet that reads “No Equipment Ground” which comes with every GFCI outlet. This lets other folks understand what is happening behind the walls in the future.

A GFCI will “sense” the difference in the amount of electricity flowing into the circuit to that flowing out, even in amounts of current as small as 4 or 5 milliamps. The GFCI reacts quickly (less than one-tenth of a second) to trip or shut off the circuit.

 

So, there you have it. If you have ungrounded outlets, you’re not stuck having to pay thousands of dollars for a complete rewire of your house. There are options to keep your family and electronics safe.

 

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91 thoughts on “How To: Fix Ungrounded Outlets

  1. I am going to put GFCI Receptacle in my old house , The house is over 30 year’s, they have the metal box’s in the house but they are not grounded. The wires coming to the box’s have only 2 wires, White & Black. I notice that in the Main Breaker Panel. The Black wire is Hot, & the White wire is neutral. In the box they have the White wire is connected to the Ground terminals.
    So if the White wire is Connected to the Ground terminal, On the GFCI can you put a short wire from the White wire to the Ground.

  2. a regular switch only uses the hot wire if you going to install a timer switch just run as pig tail from ground wire or neutral wire
    to the switch.

  3. I have a house built in 1941 that has knob and tube wiring. Anytime I try to plug in an appliance like a crockpot or toaster oven, the garbage disposal gets warm and trips its reset switch shutting off everything nearby those outlets. No fuses are trip, however. When I unplug the toaster and hit the reset switch everything else will work. Is this because of ungrounded outlets?

  4. I have a bathroom 3 gang outlet, with 3 light switches. Ground Wires are present and not used all joined together in back of box. 4 – 3 wire coming into box. One of the hot wires has 3 extensions going to each switch. All the neutrals are connected together, going no where capped off. One black wire from the other three cables coming in is connect to each switch. So, no Neutral wires are connected and no ground wires are connected. But it all works. How, and why no ground? I want to install a timer switch that needs a ground.
    Any ideas how to get a ground. The grounds in the back do not appear to be connected anywhere.

  5. I have a bathroom 3 gang outlet, with 3 light switches. Ground Wires are present and not used all joined together in back of box. 4 – 3 wire coming into box. One of the hot wires has 3 extensions going to each switch. All the neutrals are connected together, going no where capped off. One black wire from the other three cables coming in is connect to each switch. So, no Neutral wires are connected and no ground wires are connected. But it all works. How, and why no ground? I want to install a timer switch that needs a ground.

    1. I am thinking that the wire bringing power comes from a GFCI outlet. Possibly why the ground is not working?? When I connected a power outlet using one of the twisted ground wires and a tester plug for proper wiring, it passed no red light indicator, 2 yellow lights polarity passed. Still puzzled why the Lutron movement switch will not work with the ground from the box connected. Others in the house do. It is a plastic box.
      Any help appreciated.

  6. Just bought an old farm house, almost all outlets have been updated in all but a finished attic, which lets me HOPE the house is grounded.
    In the finished attic there is a series of 4 plugs with the old 2 prong non grounded type faces.
    If I pull them out, the box is some old weird plastic/ceramic material (like old frying pan handles) with no ground visible.
    The wire coming in the back has white/blk/bare wires.
    Can I with any confidence presume/assume the loose bare wire is a valid ground and just connect the green ground screw on the new outlet to that and call it good?
    I did replace the first outlet in the branch with a GFI outlet with no ground and it seems to work but when I put a second GFI outlet next down the series it does not work, nor do any outlets beyond it down the circuit. So I am assuming a 2nd GFI will not work linked behind a first one but if I can just use that bare wire to ground I can can replace all of them with plain non gfi grounded outlets.

    1. I don’t think you can make that assumption. I just bought a house built in ~1905, and many of the outlets are 2-prong outlets with a third, unused bare wire in the box. I assumed these were grounded and installed a couple of 3-prong outlets where I needed them the most using the bare wire as a ground. My outlet tester kindly informed me that these new outlets I installed have an open ground, so the bare wires are in fact not grounded (I suspected this might be the case when I noticed the gauge is smaller than what’s typically run through a house during installation, and smaller than the adjacent hot/neutral lines).

      I’m leaving these as they are for now, which, as outlined in this article, is generally okay but not as safe as having a properly grounded outlet. They’ll have to be fixed a little later when I have more time to get back to them. If you need to have the third prong for anything right away (I needed to run a couple of AC window units), I’d recommend using an adapter as a stopgap rather than replacing the outlets since it’s easier and does the same thing, but make sure to come back to them soon and get them grounded properly. I’d definitely suggest getting an outlet tester to check your work when you do it. They’re cheap and easy to use.

  7. I am one of those annoying do it yourself homeowners. I am rewiring my house. I am trying to replace that old nasty silver 2 wire with 12 gauge. I have been pretty successful up to this point. I am now rewiring the living room. It is a ranch home with a hip roof. I can rewire most of the circuit but I can’t reach the last two receptacles under the eaves at the front of the house. I can’t pull wire to those receptacles because the last part of the leg goes into a 4 gang switch box by the front door which I don’t want to mess with and then from the switch box to those 2 receptacles.
    This is where the stupid annoying do it yourselfer comes in. All of the circuit now has new 12 gauge and is grounded except for those last 2 receptacles. What is the proper procedure for these last 2
    receptacles.

      1. Jovet, you are absolutely right. So I still can’t pull that wire because on top of everything else, it is the only wire in the whole house that they decided to staple. So, after sleeping on it, I’d rather eliminate that receptacle. Thanks, sometimes tough feedback is just what the doctor ordered.

    1. Remove the baseboard along that wall and cut the drywall at the bottom 4-6 inches. Then drill the studs and pull your new wire. Old wire can be cut off at the sheathing and left in place.

  8. I have a question about “grounded” and open ground on a gfci. I took out an ancient GFCI from my bathroom after trying to plug a snajke into it and when the tip of the snake hit the cast iron toilet flange it sparked like a welding rod. Switched to another outlet. Not sure what happened but pulled out the old GFCI and replace it. I didn’t look at the setup on the wires but something I was not used to. Originally there was a metal box in there but I switched that about 5 years ago. Anyway, put in a new GFCI and the wires were weird… or to me weird. There was a hot red, hot black and neutral and ground… so easy uh? there were also one set/ black and white only… heading down the circuit to garage, hallway.. etc. No matter how I hooked it up.. it still showed open ground. I hooked to two hots on the line side, the neutral on the opposite side, and the existing ground to the ground …. then the other two (black and white only) to the load… all was fine EXCEPT the open ground. The only think I can figure out is that the “ground” somehow needed the metal box and since I took it out… I was out of luck? Tried the ground several different times but still showed open ground. ground wire is coming from where the red/black and white came from but I guess it’s simply not grounded? Am I still safe using that outlet in the bathroom? Would appreciate some advise. Still confused about the two hots coming from the line side.. but maybe that’s “normal”?? Thanks, Brad

    1. You would have to check where those cables end up to see if and how the ground wires are hooked up. It’s a bit difficult to guess why there are two hots without seeing it. But, as long as you wired the incoming power to the LINE side of the GFCI, it should be okay.

  9. We bought a house, knowing that the 3-prong outlets were ungrounded; our inspector did a very thorough job and tested every outlet. We should have demanded that the seller rewire the house, but we simply didn’t think it was an issue. Now I have a surge protector that won’t work upstairs because it requires, and can somehow detect, the ground connection. We’ll need to bite the bullet and rewire the house, necessary but expensive.

  10. I hate further complicate this discussion but there are already code requirements in many municipalities that require arc-fault protective outlets or breakers to be installed in all circuits in bedrooms in residences. Some areas require them in other rooms as well. These differ from GFCI’s (ground fault circuit interrupters) in that they are intended to prevent fires caused by electrical arcing, which is a major source of home fires. These are caused when objects like draperies, bedding, toys, etc. that are pushed up against electrical outlets and cause plugs placed in them to become loose or displaced and create arcs (electrical sparks) between the neutral and “hot” lines.

    I highly advise against most homeowners trying to “fix” these situations themselves. You really need a licensed electrician who is aware not only of the codes that affect local installations but who understands what is and is not a safe practice. Unfortunately, due to the inconsistent licensing and inspection practices around the country, especially in small town and rural areas, it may not be easy to get good advice or qualified workmen. Before I was retired I was a licensed electrician and certified electrical inspector — the ignorance even among my peers in the trade was scary.

    One of the prior commenters is correct: BX (metal armored cable) is NOT considered a viable path to ground and should not be used for chassis grounding. Rigid metal conduits, like EMT, used with metal boxes, does meet the qualifications.

    1. BX cable is too generic a term. The armor on type AC armored cable (has a bare aluminum jacket bonding wire) is an acceptable ground path however, the armor on type MC metal clad cable is generally not an acceptable ground path unless listed specifically by UL such as Type MCAP that has an interlocked armor tested to be part of the grounding path along with a bare aluminum conductor which is in contact with armor continuously to form the entire ground path . Usually plain MC cable includes a separate insulated ground conductor which is intended to be the ground path, not the armor jacket.

  11. I live in a city with city water. I have a old house that has two prong outlets. If I put three prong outlets in and run another wire and hook it to the nearest cold water line is this ok and legal. The main box is hooked to a cold water line thank you

    1. In General NO! The electrical and water systems must be bonded but only nearest the contact with the ground outside. Your water mains may be plastic, the plumbing inside may not be continuous copper, there are many reasons why this could be a non viable option outside of what allowed by code. But according to the NEC 2017 (National Electric Code) this is not considered an acceptable ground path.

      1. Also, this may “blow” the pipe. My sister’s house was done this way in her bathroom. We ended up having to replace the pipe for the shower. All i did was flip on the light switch. ALWAYS BEWARE OF PREVIOUS WORK NOT DONE CORRECTLY AND TO CODE.

  12. If I ran a 3 wire to one receptacle on the run and attached it to a gfi would that give me the grounding needed for the other receptacles on that same run?

    1. That would not give you a ‘ground’ on the downline outlets, but it would cut off power to them so long as the downline outlets are connected properly to the GFCI outlet. I’m not aware of any GFCI outlets that don’t protect downstream outlets, but do your due diligence and read the packaging, just in case. In order for any outlet/device to be grounded it has to have a path to the ground. In your situation, as you’ve described it, the ground path ends at the GFCI outlet.

  13. I am a 28 yr real estate broker & 10 years prior to that in building supplies…if you have a 3 prong outlet that isn’t grounded & you can’t easily ground it, replace with a 2 prong outlet. I never commit my clients to grounding outlets. I make sure we put in writing if they can’t ground they go back to 2 prong.

  14. There is another option. If your house has radiant heating, You can run a ground wire to the radiator and use a water pipe ground clamp. This wire can then be grounded to a surface mount outlet box like those found in an office. Then run a metal raceway from the first box to other surface mount plugs around the room. A lot cheaper than rewiring the house and you now have a grounded circuit.

    1. Sorry to jump at this late date. Is the presumption that a house with radiant heat has metal piping to ground through/ I have radiant heating but my system uses PEX tubing which is not metal at all.
      Jim

    2. That sounds good but if the connection on the radiant heat gets loose it could potentially put a small hole in water line and make a horrible mess

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