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I'm looking at a home for my family and trying to assess the amount of work needed (no home-inspection is present). I saw that most of the electrical ports have 2 prong outlets and am worried that I might have to add grounding to the entire home which can cost 10k+.

I noticed though that the Bathroom outlets have 3 prong sockets though. Does this mean I might not have to re-do the entire house and just change the electrical sockets? Any help is super appreciated.

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    Can you get us photos of the insides of some exemplar electrical boxes? (preferably at least one of the bathroom boxes with the 3 prong receptacles in it) – ThreePhaseEel Jan 12 at 1:22
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    While not ideal, you can replace every outlet with a GFCI outlet, which is completely legal, and safer than than 2 prong outlets. They cost more than your traditional outlet, but a heck of a lot cheaper than $10k – dberm22 Jan 12 at 13:26
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    @dberm22 No, mercy! No! You are suggesting an utter clusterf*ck of a headache. They sell GFCI breakers for this purpose. If you go the GFCI outlet route then make sure to only install it as the first one in the series of outlets (line); the rest on the load side can be regular 3-prongers. – MonkeyZeus Jan 12 at 15:25
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    @SteveSether I did this with my 1940 house and it's existing (albeit updated) panel. My comment was more against daisy-chained GFCI than it is pro-GFCI breaker. – MonkeyZeus Jan 12 at 17:21
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    @SteveSether, I'd say it's better than 50/50 -- a lot of the panels from back then (GE, Bryant, Gould, ITE, Challenger, etc.) are fully supported by modern breaker lines. And most of the ones that aren't supported dropped that support for good reason: they tend to cause fires (FPE, Zinsco). The only panel line I can think of that is perfectly functional but doesn't have modern breakers available is Pushmatic. – Nate S. Jan 12 at 17:31
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Grounding is no longer red-alert essential

Since there are other ways now to provide better protection. Particularly, GFCI protection is so good that you're allowed to fit 3-prong outlets as long as they are protected by a GFCI device (somewhere in the circuit).

So all these are acceptable:

  • A socket that's obviously a GFCI, with "Test" and "Reset" buttons.
  • A socket that has a "GFCI Protected" sticker that is protected by a GFCI device somewhere else (e.g. GFCI breaker or GFCI socket upstream).
  • A 3-prong socket stickered with "GFCI Protected" and "No Equipment Ground".

Note that GFCI does not provide "Equipment Ground", or the ability of equipments to dump lightning, ESD and surges to the earth ground (which doesn't exist).

Retrofitting ground isn't as hard as it used to be

NEC 2014 broadened the rules for "retrofitting ground" to outlets not currently grounded. Today, you are allowed to simply run a proper-sized ground wire, via any route, to any of the following:

  • The panel (obviously)
  • Any junction box that has a big enough ground going back to the panel
  • Any junction box with hard metal conduit going back to the panel
  • The Grounding Electrode System (bare wires from panel to water pipe/ground rods)

And circuits can share grounds -- you can't share neutral because that is normal service current and it can overload, but ground faults are rare events, and you're allowed to presume that you won't have 2 of them on 2 different circuits at the same instant.

Also, grounding may be there anyway. Some old houses were wired with metal conduit or metal-jacketed cable. This, combined with broad use of metal boxes, sometimes means grounding actually is present after all. You can't tell this except by opening up junction boxes, but it's a pleasant surprise. The houses done in conduit can even have the wires replaced with little pain - the conduit lasts forever.

So you can often use a "combo tactic" of GFCI protection + actual grounding for the receptacles in the computer room.

Worry more about the panel

Certain types of panel are toxic -- Federal Pacific and Zinsco. Those panels must go entirely. Swapping panels is a big job, pencil in $2000.

One panel line, Challenger, has dangerous breakers trivially replaced with modern breakers.

Other panels such as Pushmatic or old GE, are perfectly safe (Pushmatic is "the finest consumer panel ever made" say some), but are obsolete meaning modern safety-enhanced circuit breakers can't be obtained. (at least not from reliable US vendors; the Chinese will supply dangerous junk of course.)

Still others (ITE, Crouse Hinds, Westinghouse, Challenger etc.) are obsolete in name, but fully supported by modern breaker lines.

The reason this matters is that AFCI and GFCI breaker types enhance safety considerably in old wiring. AFCI attacks the problem of arc faults, or faulty old wiring that arcs, overheats and starts fires. GFCI provides shock protection for humans which is significantly better than the protection provided by grounding.

As such, it's possible to secure old wiring and even "dangerous" aluminum wiring well enough to continue it in service.

Although to tell you a secret, the problem with aluminum was never the metal. It was bad choices about attaching it to terminals not actually made for aluminum wire, and using improper screw torques. In 2017 they require a torque screwdriver for all connections; that and CO-ALR rated receps and switches, you barely even need the AFCI breaker at that point!

  • Never heard of Crouse Hinds; is that what CH usually stands for? I have been assuming Cutler Hammer when I see CH. – TylerH Jan 12 at 14:40
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    @TylerH, no, generally CH refers to Cutler Hammer as you assumed. Crouse Hinds breakers are part of the Siemens/Murray/ITE/Gould breaker lineage (source: forums.mikeholt.com/threads/…). – Nate S. Jan 12 at 17:11
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    What Nate says, but Don't use CH as shorthand for Cutler Hammer. That's because Cutler Hammer makes 2 residential panel lines: BR and CH. So if you send someone to the store to get CH breakers, they will come back with literally CH breakers. 3/4" wide with a tan handle, and they will not fit in your BR panel. – Harper - Reinstate Monica Jan 12 at 17:53
  • Its funny that houses in your country are so nw that you don’t meet Bad cables, in Germany and putted wiring or distribution panel means it’s high time to rip out the old cables, Changes.are high they have porous isolation, inadequate gage, knoted junctions, mixed phases and other problems. When investing in buying a home really check for that (not to mention poor locations for sockets and switches). Having no ground would be just mean the wires are post-war time here ... – eckes 2 days ago
  • Why are Federal Pacific and Zinsco considered toxic panels? Also, are these panels US-only? – Nzall 2 days ago
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There are a few possibilities:

  • The bathroom outlets were changed to three-prong and the ground screws are unattached. This means they're not grounded and are potentially unsafe.
  • New wiring (or retrofit grounds) were run to the bathroom. This means they're grounded and relatively safe (they should still be GFCI protected).
  • The outlets in the bathroom have "bootlegged" grounds--they're connected to the neutral wire. This is illegal and unsafe and should be remedied immediately.

None of this tells you much about the house in general. You'll have to pull outlet covers and look. You could also pull the panel cover and check for a ground bus bar and any connections.

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    Or these are outlets with integrated GFCI. Comparing the currents on hot and neutral, and switching off on discrepancy works even if there is no "real" ground connection. Not optimal, but it will trigger for a class 1 device with the hot wire connected to the case. – Simon Richter Jan 12 at 13:34
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    Using a GFCI without connecting a ground is legitimate if the outlet is a GFCI marked "No equipment ground", or if it is GFCI protected and is marked "GFCI protected; no equipment down". – supercat Jan 12 at 20:22
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TL;DR Unless there is a major panel replacement needed, you're looking at hundreds to replace every receptacle and/or add GFCI protection, not thousands.

The electrical code (NEC) and actual practice have evolved over many years. Ungrounded receptacles are not ideal, but are not inherently unsafe. If they were, then there would be no such thing as devices that use two-prong plugs instead of three-prong plugs, but plenty such devices are still manufactured - including cell phone chargers, lamps and many small appliances.

In a perfect world, every advance in safety would be retrofitted everywhere. We don't live in a perfect world and we need to balance the cost vs. benefit of such changes. My personal opinion is that the most beneficial change is GFCI - it provides critical life-safety protection at a relative low cost, and despite "ground" in the name, it can be done without a ground wire!

Your specific situation sounds like many houses from the early-to-mid 20th century. There are actually a few possible situations, and you may even have a mixture throughout your house:

Types of Receptacles

  • 2-prong receptacles with no ground available

These are quite common, and in areas that don't have a major water concern (living room, bedrooms, etc.) it is OK to leave them as is. But if you want to add some real protection, you could upgrade to GFCI-without-ground (more below).

  • 2-prong receptacles with ground available

If you have metal conduit and metal junction boxes, then you may be able to use that as a ground connection and install grounded receptacles easily.

If you have non-metal conduit, you can add a ground wire relatively easily. Just add a bare or green wire of the appropriate size (12 AWG for 20A, 14 AWG for 15A) into the conduit.

You may also have cables that include a ground wire and find that it is available to connect to the receptacles.

In these three cases, you can install grounded receptacles at minimal cost.

  • 3-prong properly grounded receptacle, without GFCI

This is likely what you have in the bathroom. If so, upgrading to GFCI protection (more below) is a really good idea.

  • 3-prong receptacle without a ground connection.

There is a small possibility you have these receptacles. If so, that is a real hazard as it provides the appearance of protection without actually protecting you. These should be upgraded to GFCI protection.

  • 3-prong receptacle with a bootleg ground

This is where ground is connected to neutral. Not so likely here, I hope! But possible if the owner before the last one had a situation of: Home inspector says "you should have grounded receptacles in the bathrooms", owner "fixes" by replacing 2-prong receptacles with 3-prong receptacles but wires neutral to ground instead of running a new cable with a ground wire, buyer tests (but doesn't open receptacles) and verifies that all lights on the tester are "good". The only way to tell if you have a problem of this type, which would be a big red flag about workmanship throughout the house, is to open up a receptacle and see how it is connected. But even if you find such a mess, it can be resolved by putting in a GFCI and leaving ground disconnected.

Add a Ground

It is now legal under the NEC to add a ground wire without actually replacing existing wiring. You can:

  • Run a ground wire (bare or green) to an already protected circuit
  • Run a ground wire next to your cable, all the way back to the panel
  • Run a ground wire through any convenient path, all the way back to the panel.

Any ground wire must be the correct size (12 AWG for 20A, 14 AWG for 15A) but can always be larger. The full path must be the correct size - e.g., you can add a 14 AWG ground for a 15A circuit into an existing 12 AWG ground for a 20A circuit, but not the other way around.

Fuses and Breakers

You may fuses, circuit breakers or a combination. If you have circuit breakers then you may be able to retrofit GFCI protection by replacing breakers. However, many older panels do not have GFCI breakers available.

Some breaker panels are BIG problems. I would be much more concerned about the status of the panel than grounding of receptacles. Federal Pacific is one that comes to mind, and I think there are others. Plus even a good panel can have improper wiring, wrong breaker types or other problems. Upload a picture of your panel and the experts can give some advice.

GFCI

GFCI, Ground Fault Circuit Interrupters, watch for any imbalance in the current going in/out of the circuit, either between two hots (240V) or between hot & neutral (120V). Any "lost" current is considered a ground fault, but that doesn't mean it went through the "ground wire", it could be going through a person to the physical ground, which can be deadly. A GFCI acts fast enough to save lives. Areas with water are the most vulnerable, since wet skin conducts much better than dry skin. As a result, GFCI protection is, generally speaking, require in new circuits in kitchens, bathrooms, laundry rooms, garages and outdoor receptacles.

The good news is that GFCI protection (a) does not actually need a ground wire to do its job and (b) can be installed wherever it is easiest - in the breaker panel, between the panel and the first receptacle to be protected, or in combination with the first receptacle to be protected. If there are multiple receptacles on one circuit to be protected, they can all be protected with one GFCI unit, provided it is properly installed.

The end result is: If you are concerned about lack of grounds, and there are no ground wires available, you can protect the circuits using GFCI at a reasonable cost.

However, while GFCI-without-ground-wire does provide life-safety protection and also effectively takes care of certain other faults that would not in the general sense, in the absence of wet skin, be considered immediate life-safety threats, that would otherwise get handled by the traditional ground wire, it does not take provide a route for the energy that surge protectors would normally dump on the ground wire. If you have sensitive electronics designed for a 3-prong connection, they (and any surge protectors they are plugged into if they are not plugged into a receptacle directly) ideally should be connected to actual grounded receptacles and not receptacles that have GFCI-without-ground-wire.

You can get a simple tester like this one: Klein RT210

to test receptacles to see if they are properly grounded (and check for certain other problems as well) and also to see if they are GFCI protected. Note that, ironically, the GFCI testers often do not work if there is no ground wire, because they work by taking some of the current that should be going from hot to neutral and sending it to ground. If there is no ground, then the current doesn't flow - and the GFCI doesn't trip!

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    Also, if there is no ground wire, your surge suppressors protecting computers and other expensive electronics will not work, since they use the ground wire to dump the voltage spike to, well, ground. – Jon Custer Jan 11 at 23:50
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    Actually, if the previous owner bootlegged the grounds on the outlets, the 3-light testers will give you a false sense of security. – DoxyLover Jan 12 at 1:36
  • @DoxyLover True. But if (as indicated in the question) the 3-plug receptacles are in the bathrooms, those need to be on GFCI, which will require either verifying existing GFCI functionality or adding GFCI. So end result is that they will get checked anyway. But I'll add another possibility. – manassehkatz-Moving 2 Codidact Jan 12 at 1:42
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    Your "Add a Ground" section looks incomplete. "...replacing existing wiring. If y". If I what?? – dberm22 Jan 12 at 13:15
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    Does that mean I can use steel conduit as the ground wire? – Joshua 2 days ago
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I want to start by saying that I'm not an electrician. There is a lot of training and certification/insurance that goes into that. I just want to share my experience with my first house I purchased almost a year ago and what I learned along the way.

There isn't a yes or no answer to your question. You have to figure out what is going on and determine what you will need (speaking about the two prongs, not the bathroom GFCI).

Mine is a pretty small house, 100 Amp panel, the whole place was two prong as you described, with three prong GFCI in the kitchen and bathrooms. They had the protected sticker on them also.

I wanted three prong throughout the house for convenience, so I was going to be doing some work anyway, although I was told by a few people in the business that wasn't as necessary in a grounded panel because the neutral gets connected to the ground in the panel. Plenty of electronics only had two prong anyway. I mentioned its up to you to decide what you want because in theory you could get a ground running to the bathroom, kitchen, laundry room where its needed the most and save by leaving the rest of the house as is.

Electrician told me that I had GFCI, so if it was legally installed (its own third wire for ground) my panel ought to be grounded, saving me at least some money. A grounded panel has a third wire going out to a pair of stakes buried around 6 feet deep in your yard. Our panel didn't have that so we decided to test with the GFCI tester and they failed. My panel was ungrounded and illegally installed. It also had spliced wires in the panel that were rubbed against by the panel cover. My electrician didn't even want to close the panel after that until the utility company cut power to my house.

In the end I wound up getting a new 200 Amp panel (installed in the basement instead of outside), two stakes in the yard, a second panel in the stand-alone garage, the whole house got three prong grounded, and the GFCIs were fixed. This all cost me around $8,000 - $10,000. I got away a lot cheaper because I have an unfinished basement and crawl spaces in parts of the finished attic that gave access to all of my outlets.

I wanted to share that story amongst other great answers because they didn't really hit on the fact that it's up to you to figure out what is really going on. The sticker or the illegality of the install isn't going to protect you from harm. If you find problems in the most overt places, imagine what could be hidden inside your walls.

Edited: Fixed the line line about the spliced line in my electrical panel to clarify why it was not good.

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  • Everything I've read & been told is that splices, when done properly, are perfectly legal inside the panel - after all, the panel is just a big junction box. Ask your electrician to quote you NEC saying they're not legal. – FreeMan 2 days ago
  • @FreeMan I don't know either way. We've also got state codes. Maybe it was his rule of thumb. In my scenario it was bad because it was the live wire going to the street that was spliced and taped up with a bit of electrical tape. That live wire sat right up against the part of the panel where the cover had to be slid into place before screwing it down. Exposing the insides basically rubbed the sharp edge against the splice. – SomeGuy 2 days ago
  • That is different. Thanks for clarifying. – FreeMan yesterday

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