There is a room in my house that has outlets that, when I open the box, I see have no ground. I want to use them for electronics and there should be a ground. How do I fix this situation? The outlets are in boxes with the cabled in metal conduit leading to the boxes. Thanks.
paul
snipped-for-privacy@yahoo.com (Paul Stewart) wrote in news: snipped-for-privacy@posting.google.com:
If there is no ground pin you don't need to open anything to see that, so it sounds like when you say "no ground" you mean "there is a ground pin but no ground wire going through the conduit". In fact the metal conduit itself is frequently used to carry current to ground. It is in electrical contact with the box, and the box is in electrical contact with the outlet assembly, and so the third pin is connected to the conduit...
Buy or borrow a ground tester and check.
Get a socket tester, it tells if the socket is wired correctly. If you have a metal box they should already be grounded
Well, looking at the open outlet boxes in this room, I see that there are two and only two wires leading off from the outlet itself up into the conduit (headed back to the fuse box). Black and white - no third ground wire, connected to the conduit itself or no. So it must not be grounded, yes?
I suppose I should get a ground tester.
bp
According to Blake Patterson :
He's trying to tell you that the conduit itself _can_ act as a ground. If the conduit is metal, if the conduit is continuous back to the panel, if the receptacles have three prong outlets, the outlets probably _are_ grounded already.
The trick is, _is_ it metallic, continuous back to the panel, do the receptacles have a third ground pin?
Right. If the receptacles are three prong type, the only way to tell whether the receptacles are truly grounded already is to test them.
You may want to consider perusing the section in the electrical wiring faq (google for it) and checking the section on that specifically. Testing grounds properly isn't as easy as it appears.
It is permissable to use the metal conduit as a grounding conductor, however the outlet should be the self-grounding type or have a green or bare wire connected to the green screw of the outlet and to the metal outlet box.
A self-grounding outlet has a small brass or copper clip on one of the receptacle's mounting screws to ensure good grounding continuity from the box through the screw to the outlet mounting strap. I'm not sure if these are permitted anymore. A green or bare wire is the best way to go and must be connected to a green machine screw (10/32) on the box that has no other purpose.
Hope this helps.
John Grabowski
Blake Patterson wrote in news: snipped-for-privacy@news.verizon.net:
You're obsessing on wires. The outlet assembly may be electrically connected to the box at the points where the screws attach it to the box. The best way to find out is to use a ground tester (about $10).
I see no wire but the two wires coming into the outlet - black and white. A ground tester shows it has a clean ground signal though (just picked one up).
bp
Several people replied to this thread but no one really gave an answer to the original question: how to ground when there is no ground. I think people assume a BX cable when seeing a metal box. But I really need the answer to the original question.
This happened to me several times. The cables all had a plastic sheath with only two wires in it. And when I tested the receptcles with a tester, sure enough, there was no ground. In one case, I drilled a hole from crawl space through the floor and through the box. I then ran a bare copper wire, one end to the green screw (of a new receptacle, the old one having only two holes) and the other to copper pipe. I had heard people saying one should not have two different grounds but I think that would not be worse than having no ground.
Or sometimes they assume pipe or EMT.
A friend who is in the process of gutting his 2nd floor has the same stuff, only there is a ground wire - it's folded back over the sheath before the cable was secured into the box. All the ground wires were "loosley" twisted in the wall cavity. Sometimes, it's secured to the same screw that holds the side of a gangable metal box.
The issue here is, that's not a code compliant method of grounding an ungrounded receptacle.
The correct solution when there is no ground, and no hidden or buried wire, is to simply rewire the individual outlet new back to the panel.
Keep in mind, very few things require grounded outlets these days. Aside from computers and their accessories, you'll typically only find grounds on large metal appliances. Even most power tools and kitchen appliances are double insulated and have no 3rd prong.
According to John Smith :
Do recall that the original poster explicitly said that there _was_ metal conduit. So the original question was answered up to the point of the original poster continuing to be fixated on the fact that there's only two wires. The conduit _itself_ is a grounding conductor (under US code), if it's continuous back to the panel and the outlets have standard internal strapping arrangements (mounting screws interconnected with ground prong). Hence everyone suggesting he test it.
Two wires with plastic sheath is a different question from the original poster's.
The question you have to ask yourself first is, "do I _need_ to ground them?"
If you're concerned about shock and fault hazard, you don't _need_ to ground the outlets. Install GFCI (or AFCI) outlets instead. It's more effective than grounding from a personal safety/fire perspective, easier, and probably cheaper. And perfectly legal.
Grounding is usually only essential for spike and surge suppressors, tho, fluorescent fixtures like seeing "real" grounds.
Grounding to a copper pipe can be worse than useless - it can be very hazardous.
If the copper pipe isn't continuous back to the grounding electrode (eg: there's a bit of plastic pipe), a short inside an appliance can make all of the plumbing and fixtures in your house potentially lethal.
This is why both Canadian and US code now forbid the use of copper pipe for grounding (tho exceptions are sometimes made if you prove full conductivity back to the real grounding system). US code permits metallic cable sheath (BX, conduit etc - original poster's situation). Canadian code does not. Both _prefer_ a real conductor back to the real electrical ground.
Even BX cable came with internal ground wire. Two wire is typically pre-1960 buildings. There is no way around the solution. A third ground wire must make a dedicated connection from breaker box safety ground to receptacle's safety ground pin. GFCI kludge will provide human safety and is permitted by code. But electronics assume that ground wire to breaker box will exist - so that 60+ volt potential differences do not exist between interconnected peripherals.
BTW, that third wire ground does not provide earth ground to make surge protectors effective. That safety ground wire for surge protection is urban myth. Receptacle ground wire is necessary so that common mode I/O ports do not suffer from that 60+ volt leakage - due to no safety ground. Note the adjectives - safety ground and earth ground.
Will that three prong tester report a good safety ground? No. It can report a missing safety ground BUT it cannot report a good safety ground. Furthermore, what those who recommended surge protectors forgot to mention - surge protection is only as effective as that earth ground. No earth ground means no effective surge protection. Since plug-in surge protectors don't even claim protection from typically destructive surges, then they (conveniently) forget to mention the so critical 'less than 10 foot' connection from breaker box safety ground to earth ground.
Can't figure out how to safety ground those 2nd floor outlets? Amaz> Several people replied to this thread but no one really gave an
Yes, I am an electrician, and this is very dangerous. If there is even one piece of plastic pipe, or a dielectric union in the piping, you could end up with a live faucet in your bathtub, or anywhere else. You are better off NOT grounding at all, if this is what you are doing.
WIthout seeing your house, it is hard to say what you got. But here are a few suggestions. That ground wire that you ran, could be taken to the breaker box and grounded there. That would be safe. But if you are going to tear holes in the walls to run one wire, why not just replace the wires with modern, grounded, sheathed cable (romex). Just do a few outlets at a time. The ones on the first floor (assuming there is a basement), should be fairly easy to change. You are only a few feet away from the floor. The outlets that need grounding the most are in the kitchen, where there are appliances. Do those first. If you have a computer (obviously you do), run a new circuit to that location. Most other outlets in the average home do not need grounding. For example, the living room. What do you got plugged in there? Probably a few lamps and a tv set. None of these even have a grounded cord.
If you got a work room with power tools in the basement. You should have grounded outlets there. Also your washer and dryer. If those things are in the basement, and like most homes the breaker box is there too, just run some new wires. That should be easy.
Please remove that wire to the plumbing, and at least ground it to the breaker box.
Good Luck
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