I have read the postings on this topic in this news group and haven't
found one quite like mine so....
Yes, I live in a 1959 house, and the house sockets are only two
Now, when I removed the faceplace and socket, I found wires entering the
metal box from the top and connecting to the socket. And another set
connecting of wires connected to the same poles exiting the bottom of
the box... At both the top and bottom of the box there is a cylindrical
opening which the wires pass though. Coiled around the cylindrical
opening is a bare copper wire. The coils of bare copper wire are on
both the top and box and the trailing end exits the
Here is my situation. I removed the faceplate covering an two pronged
outlet, and then removed the outlet itself ( yes, breaker was opened
prior ). Inside I found wires entering the metal box from both the top
and the bottom. One black, one white from both the top and the bottom.
These were connected to the outlet. In additon, coiled around the
opening at both the top and the bottom of the box is a bare copper
wire. The bare copper wire is crimped to the box, but not continuous.
Two seperate copper wires are visable. Neither wire was connected to
Now, does this possibly mean the socket can be updated to a three
pronged outlet by attaching a grounding wire to the box? Or in other
words, how do I test to see if bare copper wire is actually a grounding
wire and thus will work safely with a three pronged outlet?
I am confused. You mention that a bare copper wire is crimped to the box
(do you mean attached with a clip?) and also that there are bare copper
wires not attached to anything.
So, how many bare wires are there, and are they attached to anything?
Presumably you have no test equipment, and you probably don't want to buy
any, so you can't check continuity or voltage to "ground". You could take
the cover off your panel and see if there are bare copper wires there
attached to a grounding buss. Assuming there are, the wires in your box are
Assuming your box is steel, and that the bare wire is clipped to the box,
then a 3 hole outlet will be automatically grounded through the attachment
strap. However, it is preferable to attach the ground wire to the green
ground terminal n the outlet. It is also a real good idea to buy a $5
circuit tester to confirm you have done it properly.
I was confused when I wrote it.... sorry.
The box is metal - steel I assume. There are knockout holes top and
bottom through which the wires enter the enter and exit the box. The
white and black wires are connected to the outlet. White wires to the
silver colored terminals, the black to the brass colored terminals.
This is currently a two pronged outlet so there is no ground (green)
terminal on the outlet.
Now, at the openings of each knockout, there is a piece of metal which
crips the wires at the opening of the knockout. I guess to hold the
wires in place so they are not pulled out. It is to this piece of
metal to which the bare copper wire is wrapped and crimped.
I do not have any test equipment, but I am not against buying the
required tools/testers. It was suggested by an individual that I could
run a tester from the black (hot) to the bare copper wire while the
power is on. If the bulb in the tester glows, the bare copper wire is
a ground. He also suggested a volt meter which would show a result of
110 volts in the same set up if the bare copper wire was a ground. If
the bare copper wire was not a ground, then neither the bulb would
glow, nor the volt meter register 100 volts. Sound like good advice?
I have yet to remove the panel from circuit breaker box....
I do intend to run a bare copper wire from the green terminal to a
screw attached to the metal box.
Thanks for the help. Any further insight appreciated.
Okay, that is just a cable clamp, and isn't adequate for a ground; at least
not on any I have seen.
Those tests are fine. If you are going to do any future electrical work,
invest $40 in a volt-amp meter. If this is probably about it, then $2 for a
cheap tester (two contacts with a bulb) will be fine; though a $5 circuit
tester (a plug with three lights on it) is always a good investment for
testing the outlet when you are all done.
Even if you can use the ground (and I expect you can) it may not work at
that outlet. It has to be attached at all the preceeding outlets on the
circuit first. I hope the reason for that is clear.
That will only work if the two bare wires are securely attached to the box.
They sell green clips to do that
Properly, you should take the two bare wires and add two pigtails, and
connect all four wires together with a brass crimp; run one pigtail to the
outlet ground terminal, and the other to the box.
If you want a simpler method that is still adequate, they have green
wirenuts that have a green wire coming out of the end. Stick your two
barewires in the wirenut, and the green wire to the grounding terminal on
the outlet. The box is then grounded through the outlet strap.
Actually they aren't. For example, if you have a neon tester, touching
one lead to hot, and the other to your fingers will have the bulb glow,
and you're a lousy ground.
You need to be able to show that (a) the resistance is low and (b) it's
capable of withstanding substantial current. Neither a "bulb tester" nor
voltmeter will show that.
The electrical wiring FAQ suggests wiring a 100W lightbulb from hot
The above is if the ground wires aren't long enough to touch. But, instead
I'd: wirenut a short length between the two wires, with another length going
to the box and then to the outlet screw. Two wirenuts, no crimps, two
extra lengths of wire.
Assuming the cable's ground wires aren't very long, but long enough to
meet, wirenut the two wires plus a long third one. Run the other end
of the third one under a box screw and thence to the outlet screw. Only
one wirenut and one length of wire.
If the bare grounds are quite long, run the "feed side"'s bare ground
to the box screw, thence to the outlet screw, then wirenut the end to
the other cable's ground. Only one wirenut, no short pieces of wire.
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
Just a comment,
The handiest thing in my fathers tool box "and I still have to this day" is
a rubber pig-tale-standard screw shell- light socket with a 220V/60W- rough
Yes if you can afford it buy good test equipment and LEARN the POROPER way
to use, but get it from electric supply house where the profesional
contractor gets his...NO thats not Wal-Mart....LOL.
Oh by the way, yes I am a newbee and I think I see a lot of real good advice
in here .... been lurking for a while off and on.(I'm in the middle of NY
State near Coopoerstown..US.) I'm old and retarded.... ;-)
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