How to ground electric outlets over a slab?

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I used to own a house that was built on a stemwall foundation. I grounded the electric outlets by drilling a hole up through the bottom plate under each outlet box, pushing ground wires up through the hole, and fishing them into the box.
I'm now buying a house that is built on a slab, and many of the outlets are ungrounded. How should I deal with the problem in this case?
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Do it from above.
R
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RicodJour wrote:

later, odds are there will be a ground wire rolled up under the romex clamps. This 1960 house had ground cables in place- I just had to connect them when I switched out the 2-holers for 3-holers. Were the grounded outlets wired at the same time as the ungrounded ones? If so, probably same type of wire. And you did plug one of those quick-testers into the grounded outlets to make sure they really were grounded, right? (well worth the ten bucks to have one of those in the toolbox, IMHO.)
-- aem sends...
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The house was built in 1960. I'm hoping the boxes are grounded, but if they are not, I'd like to have a Plan B.

I haven't done that yet because I don't own the house yet, but the home inspector did it, and he reported that several three-hole outlets in the original living space are _not_ grounded.
A couple of people suggested going down from the attic. I haven't examined the attic yet (see above), but I've done that before, and I can testify that several things can make it impossible, or nearly so: an outside wall under the eaves; any outside wall that has been insulated; any wall with bracing. I'm hoping there's a better way.
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Jonathan Sachs wrote:

on here that some folks said running a ground wire via a different route than the feed wire, was not code-compliant. As to some of your 3-holers showing up as non-grounded- I also had some like that, that were merely wired backward. Swapped the black and white wires, and the tester was happy. If the boxes are not grounded, and there is no painless way to run new wire to the outside walls, you may have to pick and choose which outlets Really Need to be grounded. My other house down in Louisiana is on a slab, and we had to add a couple strings to feed select spots, like for the computers, microwave, and such, on interior walls.
-- aem sends...
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aemeijers wrote:

The common 3 light testers will reliably show there is a problem (but could give the wrong problem). If the tester indicates there is a good ground there probably is, but not necessarily.
If a "grounded" outlet is not grounded it can be replaced by a 2 prong non-grounding outlet. Most equipment these days does not have a ground pin.

At least one other post suggested using a GFCI outlet. It is NEC compliant and gives you a grounded type outlet. But no ground, which may or may not be a problem. The outlet should be labeled with a "No equipment ground" label that comes with the outlet. If the circuit continues past the GFCI outlet, the circuit can be connected to the load terminals of the GFCI, and outlets downstream will be protected. Outlets downstream of GFCI protection can be grounding type but must be labeled "No equipment ground" and "GFCI protected". The ground contacts of these outlets should not be interconnected by ground wires that are not actually grounded.

Generally all wires have to run together but there is an exception for an ungrounded outlet - the ground wire can be run by itself. The added ground wire can go to anywhere on the "grounding electrode system". That includes the source panel ground bar, the heavy wires connecting to the grounding electrodes (often the easiest) or the first 5 feet of water pipe inside the building.
--
bud--

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Jonathan Sachs wrote:

Got an attic? same process, mirror imaged... (and then you'll find all the firestops in the walls...) yes it is somewhat more difficult this way, a right angle drill can help.
nate
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*What year was the house built and what type of wiring is installed?
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On Apr 28, 3:02am, snipped-for-privacy@invalid.com wrote:

For the locations where running a ground wire would be difficult or impossible, put in GFCI outlets and forget about grounding them.
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On Mon, 27 Apr 2009 19:21:30 -0700, Jonathan Sachs

How many appliances require a grounded ( 3 pin ) outlet ? In my house, that woiuld be the washing machine, and the fridge. As far as I know, all other plug-ins use a ( 2-pin ) polarized plug.
So, unless your community requires 3-hole sockets, why bother ? Just be sure that the wide slot is "neutral".
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when you decide to sell lack of grounds can move your home into the fixer upper low price category.............
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<RJ> wrote:

In my case, we have awful power, so I have two UPSes and tons of surge suppressors. If the worst should happen, the "protected equipment warranty" is void unless the UPS or surge suppressor is connected to a grounded outlet.
This may sound like a far-fetched scenario for many people, but a whole mess of people in my neighborhood lost a lot of electronics a year or so ago when there was an "incident." Even with my "massive overkill" approach to surge protection, I lost a circuit board in my air filter (at that time not protected; now it is) a circuit board in my dishwasher (only protected by the main panel surge suppressor because it's hardwired) and a really old surge strip. Dominion Power denied any responsibility; I repaired all the equipment myself so the cash outlay was below what our homeowner's deductable would have been. (lost receipt for the main surge suppressor breaker)
nate
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wrote:

*Nate, make sure that you have a good grounding system for your home. A water pipe ground and ground rods should help with your problem
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It appears to be OK although I have not investigated thoroughly (how would one test something concealed like ground rods anyway?) but everything inside the house looks copacetic. What apparently happened was that a tree fell on a high voltage power line which fell on top of a lower voltage power line thus momentarily producing a voltage 10x or more normal. With what should have been an odd failure, I feel lucky to get away as easy as I did.
But that prompts a question - short of going outside and digging along the ground cable and inspecting the number of buried ground rods, how would one determine if an older house does in fact have proper grounding? (I know, lift the neutral to the pole and see if anything blows up...)
Actually you just reminded me that we just replaced our fridge which WAS an old, purely mechanical device with a fancy new one with an electronic control/display.... probably should slap a point of use surge protector on that as well. nate
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Ground must be installed so that it can be inspected. Visual inspection is the only method to confirm an earth ground exists and is sufficient. Furthermore, every incoming utility must make a short connection to that same earthing electrode. IOW a gray NID telephone box contains a 'whole house' protector that must be earthed. Cable TV is earthed directly - no protector required. These ground wires should be traced to the same ground rod that is also just outside the breaker box.
Grounding serves two functions. First is human safety. Code states what is required. Second function is surge protection. That means grounding must exceed those requirements. Connection from each utility wire (ie breaker box, telephone NID, cable ground block) must be short (ie 'less than ten feet'). Separated from other wires. Only meets all other ground wires at the same earth electrode. No sharp bends. Not inside metallic conduit. Violation of any of these means a ground for surge protection has been compromised.
Remember what a surge proetctor does. Diverts energy to be harmlessly dissipated into earth. If ground via the safety ground wire inside romex, well, that wire also violates most every above requirement which is why 'point of use' protectors have no earthing. Which is why 'point of use' protectors do not even claim to protect from the type of surges that are typically destructive.
Sounds like your best solution is to install new grounds so that all incoming utilities make that short connection to earth. Since a surge protector is defined by quality of its earthing, then additional earthing would make an effective protector even better.
Earthing must meet and exceed post 1990 code requirements to accomplish what you are asking. Type of surge that typically destroys appliances is either earthed (dissipated harmlessly in earth) before entering a building. Or finds destructive paths through household appliances inside the house. A protector connected to earth via household wires (ie romex) is all but no earth ground. It may then earth that surge destructively through an appliance as we have seen so often. A surge diverted into and dissipated in earth need not enter a building - does not overwhelm protection that already exists inside every appliance.
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westom wrote:

<http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf - "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is the major organization of electrical and electronic engineers in the US). And also: <http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf> - "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001
The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses.
MOVs in service panel and plug-in suppressors are very effective at limiting the voltage from a surge, which is very short duration, even if it involves thousands of amps. Crossed power lines are far too long a duration and will rapidly burn out MOVs. The author of the NIST guide has written "in fact, the major cause of [surge suppressor] failures is a temporary overvoltage, rather than an unusually large surge." A few plug-in suppressors will disconnect on overvoltage, or a UPS may go to backup and protect connected equipment.

Ho-hum - the usual drivel back again.
Doesn't need a protector? The IEEE guide says "there is no requirement to limit the voltage developed between the core and the sheath. .... The only voltage limit is the breakdown of the F connectors, typically ~24 kV." And "there is obviously the possibility of damage to TV tuners and cable modems from the very high voltages that can be developed, especially from nearby lightning." (A plug-in suppressor will limit the voltage from core to shield.)

w_ has a religious belief (immune from challenge) that surge protection must directly use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. The IEEE guide explains plug-in suppressors work by CLAMPING (limiting) the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).
Note that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires.
The NIST guide, using US insurance information, suggests that most equipment damage is from high voltage between power and phone/cable wires.

Complete nonsense.
Both the IEEE and NIST guides say plug-in suppressors are effective.

If you have a surge-produced current to earth of 1,000A with a very good resistance to earth of 10 ohms, the potential of the power "ground" at the house will rise 10,000V above "absolute" earth potential. Much of the "protection" is that power and phone and cable wires rise together. That requires a short ground wire from the cable and phone entry protectors to the "ground" at the power service. A ground wire that is too long is illustrated in the IEEE guide starting pdf page 40.
The author of the NIST guide has written "the impedance of the grounding system to 'true earth' is far less important than the integrity of the bonding of the various parts of the grounding system."

Service panel suppressors are a good idea. But from the NIST guide: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."
Service panel suppressors do not prevent high voltages from developing between power and signal wires.
A refrigerator, a "one link appliance", would likely be protected by a service panel suppressor.
For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.
Then read w's sources that say plug-in suppressors do NOT work. There are none.
w can't even answer simple questions: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?
--
bud--

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citation:
bud is paid to promote protectors with the necessary earth ground connection. bud must say anything to promote plug-in protectors even though none will even claim such protection. Not one. In fact, bud's own citation Page 42 Figure 8 shos what happens when a protector is too close to electronics and too far from earth ground. A surge is earthed 8000 volts destrutively through an adjacent TV.
bud will say anything, including the usual insults, to protect massive profit margins. Even post half facts. bud even forgets the damage created by plug-in (point of use) protectors as defined in Martzloff's 1994 IEEE papaer:

Why do telcos not use any product that bud promotes? For 100 years, the effective protectors always required a short conneciton to earth. According to bud, surge energy magically disappears inside a plug-in protector. IEEE papers (including those cited by bud) say otherwise. Either surge energy gets dissipated harmlessly in earth OR it is dissipated destrutively inside appliances. bud's Page 42 Figure 8 shows that. Martzloff says that. Even page 17 of bud's NIST paper says again why plug-in protectors do not protect from surges that are typically destructive:

bud is paid to promote ineffective and obscenely overprices protectors. Even telcos all over the world (that typically suffer 100 surges during every thunderstorm) do not use anything recommended by bud. Telcos use 'whole house' protector and even better earthing. Others have spend massively on plug-in protectors and still suffered damage. We install only one 'whole house' protector so that better earthing means nothing is damaged. When was phone service lost everywhere in your town as they spend four days replacing their surge damaged computer? Never happens because 'whole house' protectors are connected as short as possible to better earthing. A protector is only as effective as its earth ground.
So where is that spec on any bud protector that even claims protection? bud says his plug-in protector are complete protection systems. bud refuses to provide even one protector spec for one simple reason. No plug-in (point of use) protector claims to protect from the typically destuctive surge. Of course not. No earth ground means no effective protection.
Defined is the earthing so essential is that a protection can do what? NIST (and literally every other responsible source) says what is necessary to make a protector effective:

How does bud's plug-in protector divert to ground? It doesn't. It does not even claim to protect from such surges. It will somehow stop and absorb what three miles of sky cannot? bud makes that claim. So bud will post more insults; keep others confused. When selling a $3 power strip with some ten cent parts for $25 or $150, then even I would sell you such devices. Profit margins are just too excessive for anyone to be honest.
But I don't post insults selling a scam. Nobody uses bud's solution where damage is unacceptable. Every where that even direct lightning strikes must never cause damage, better earthing and 'whole house' protectors are used.
What does the US Air Force demand for surge protection? In Training manuals, all protectors must be properly earthed 'whole house' protectors. Plug-in protectors do not provide protection from typically destructive surges due to no earth ground. As the Air Force says:

I need not post insults as bud always does everywhere. I am not selling a scam. Every facility that must never have surge damage significantly upgrades earthing AND installs 'whole house' protectors. Earth is where direct lightning strikes are harmlessly dissipated in earth. No earth ground means what to harmlessly absorb that surge? Even surges created by falling high voltage wires on local distribution seek earth. A protector is only as effective as its earth ground. A device that diverts surge energy harmlessly into earth. A solution so well proven as to always be required in every munitions dump.
One does not even know if his earthing exists. If an earthing wire crosses the building to connect to a water pipe, then earthing all but does not exist. Critical to effective surge protection is a short (ie 'less than 10 foot') connection to an earth ground for every incoming utility. A protector (ie one installed for free on everyone's phone line) is only as effective as its earth ground. Earth is the protection. . No insults are required to define science and expose salesmen myths. Even bud's citations say why plug-in protectors are ineffective. Where is one plug-in protector spec that claims protection? No protection claims exist for an obvious reason - no dedicated earthing connection means no effective protection. bud cannot even provide one spec - and he works for them. Which is why telcos everywhere in the world do not use bud's protectors.
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Is it possible to ask a simple question on AHR about surge protection and/or grounding without...
...never mind. I know the answer to THAT question.
nate
(you'd think I'd learn. But I seriously would like to know if there's any way to "verify" that a building ground is good without digging up the ground rods.)
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N8N posted for all of us...

I believe a megger can be used.
-- Tekkie Don't bother to thank me, I do this as a public service.
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Tekkie wrote:

Such a simple question. You would think there would be a simple answer.
Easiest is probably follow the earthing conductor to find what electrodes are used (as John suggested). A metal water service pipe is an excellent electrode [but can invoke another of w's delusions]. In older buildings the other electrode you may find is one or more ground rods. Rods are not a particularly good electrode. It is probably easier to add a rod than determine if an old rod is still good.
Measuring resistance to earth can be done with a 3 point tester - not easy. There is a simple clamp on tester. Not likely you can borrow one. A contractor may have one.
An old method I have read about is to disconnect the earthing conductor from the service and connect it to the hot through a 6.25A fuse [a standard size]. If the fuse blows fast the resistance is 20 ohms or less. I might try this but I'm not sure I would recommend it - there are a number of hazards including just disconnecting the wire. The earthing wire must not contact *anything* but the electrode. (This also depends on the earthing of the utility transformer and can result in some earthing current through other customer's electrodes.)
Crossed power lines are rare and it is difficult to provide protection.
As I noted elsewhere, much of the protection from surges is actually having the power and phone and cable wires stay at the same potential (although elevated) during a surge event.

A megger is to measure very high resistances (megohms, like insulation).
--
bud--


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