How To: Fix Ungrounded Outlets

By Scott Sidler September 21, 2015

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 it’s 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 protect 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.

 

13 thoughts on “How To: Fix Ungrounded Outlets”

  1. Hi Scott…my son bought a early 1900’s home…it still had an outhouse out back…they upgraded some of the wiring…but not all of the house…there are 2 prong outlets all through the house…I am going to check them out to see what we can do to make them safer…he also is having trouble with outlets in the kitchen…I hope I can add some new outlets and maybe run him a dedicated wire for his fridge…I sure appreciate your article…I am sure to enjoy your blog…Thanks so much…

  2. I’m beyond happy I found your blog! I am buying a 1925 bungalow in North GA and I no longer feel alone, haha! From the lack of insulation, the plaster walls, chipping paint, crawlspace critters, to the ungrounded outlets, it’s all addressed here and I’m comforted to read that everything can be fixed. Thanks!

  3. Great to know, Scott! Thanks for sharing your knowledge. We have a little bungalow in College Park that we adore and may need to call on you in the future.

    Great to meet you @flblogcon today. Let’s stay connected.

  4. I’d say GFCI would be the safer way to go here. Either way it’s necessary to place backup batteries on expensive electronic equipment (i.e. TV’s, audio equipment, computers). For surges, yes, but more so for brownouts. When the power fluctuates negatively it can have ill impact on electronics.

  5. I am a little concerned about the recommendation to use the armored cable as a ground path without the home owner making sure that they know what type of cable that they have. For example, the last two houses that I have owned have had un-bonded BX cable from the 20’s and early 30’s. Bonded BX cable would have a bonding wire running in the cable to make sure to tie the coil of metal in the cable together in a low-resistance manner, and until the 60’s, most BX does not have this bonding strip. So, even if the meter shows 110V from the hot to the metal box, where it is being grounded through the BX metal jacket, that could be a very high resistance path. Once current is actually flowing through the non-bonded cable in a ground fault situation, the high resistance could cause the cable to become a heating element and become a fire hazard. Additionally, the NEC does not list even bonded-BX as a code-compliant grounding method (even though people do use this method whether they should or not). If you do an Internet search you will see many arguments for and against using bonded armored cable as a ground. Even if a homeowner knew 100% that they had bonded cable, and that it was a low resistance ground back to the box, there are enough questions that I would not feel comfortable advocating this method on my website.

    1. Nick, thanks for your comments. I appreciate your insight on this. To be clear I’m not advocating, just trying to educate. There are always different solutions that work best in a particular circumstance. Ultimately, it’s up to the professional electrician to decide, but homeowners should know about their options so they can discuss them with the pros instead of blindly following what us contractors suggest.

  6. Good writeup. One caveat on the GFCI approach: While it protects humans, it doesn’t protect computers and other sensitive electronics as well as a proper grounded outlet would.

    1. Chris, I have heard that argument from a lot of very smart electricians while at the same time heard the opposing view from other electricians just as smart if not smarter. I’m not sure I buy that it won’t protect appliances just as well. From the explanations I’ve heard it make sense that it would protect both equally as well. But then again I’m not a licensed electrician. I’ll have to leave it up to the pros to decide. I think ultimately it depends on one electricians preference over the other.

      1. A typical GFCI outlet is protection for personnel. It is designed to trip at 5ma. It has nothing to do for appliances. If you plug an appliance into a GFCI outlet or a GFCI protected Circuit and it trips, most likely the appliance is faulty and should not be used. Surge protectors help protect your equipment from surges by clamping the voltage to a specific value. Most surges are internally based and not externally based. An example is when the AC starts and your lights dim. The inrush of current causes voltage to drop, then at run, there is a sudden increase in voltage. That is surge. Should this start up last for some long duration such as lock rotor, this condition could cause a brown out or undervoltage condition. If it holds long enough, it will cause other breakers to trip from an over current state mostly on motors. Voltage goes down, current goes up. Anyhow all this being said, If you have an ungrounded system Properly installed, do not add a grounding conductor or connection anywhere in the system unless you are doing all of it from the panel to the last device. That would include ground rod, Neutral Bonding, and water pipe ground. Most shocks in a 2 wire system were between the line and neutral. Not so much line to ground as the ground did not exist. If someone got shocked line to ground, there would be a neutral conductor actually bonding to a grounded surface to create the condition somewhere in the system.

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