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.
firstname.lastname@example.org (Paul Stewart) wrote in
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.
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
I suppose I should get a ground tester.
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_
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.
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).
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
Hope this helps.
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.
In another case, the receptacles were on the 2nd floor. How do I ground
Paul Stewart wrote:
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
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.
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
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
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.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
On 11 Nov 2003 15:35:16 GMT, email@example.com (Chris Lewis)
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
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
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
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? Amazing how an electrician with the right tools can
do it so quickly. It is why you pay him the big bucks. Then
in the meantime, he could upgrade your earthing system - so
essential to transistor safety - so that it meets post 1990
NEC requirements. Often those pre-1960 homes have more
potential transistor problems than missing safety grounded
outlets. And too many older homes no long have any earth
John Smith wrote:
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