This question was posted in another forum by someone that I know and I
thought that I would try posting it here to get some feedback on his behalf:
"In a house that has ungrounded, 2 prong outlets, with wiring in good
condition, is it acceptable (and allowed by current electrical code) to run
a separate ground wire from the outlets back to the ground at the panel, in
order to be able to replace the 2 prong outlets with 3 prong outlets?
Existing wiring is in very good shape."
Thanks John and all for your replies. I passed on the information. I had
also mentioned to him that depending on the location of the outlets, it may
be almost just as easy to run new NM wiring to the outlets as it would to
run separate ground wires to the same outlets. And, I mentioned the option
of replacing 2-prong outlets with 3-prong GFCI outlets, without running any
new ground wires etc., as long as the GFCI had a sticker that said "No
As it turned out, the outlets in question were first floor outlets above an
open ceiling basement. So, he ended up having an electrician just run all
new NM wiring to those outlets on the first floor -- basically because the
electrician said that it would take almost the same amount of effort to do
that as it would to run separate ground wires.
That is pretty much true and even considering the cost of the wire, it
is the labor that will be the expensive part.
As another poster said, you really need to verify that there is not a
ground in the existing cable. There was a period of time in the 60s
when you were required to ground the boxes but you didn't need 3 prong
outlets. The grounded Romex was available in the 50s. The house I grew
up in, built in 53, had 2 prong outlets and 3 wire Romex. We
retrofitted the 3 prong outlets, pigtailing from the box. These days
it is much easier with self grounding receptacle.
Thanks. That's an interesting point, especially since the person who
originally had the question stated that the existing wiring was in good
shape. That does make me think that maybe it was the kind of wiring that
included a ground wire to metal outlet boxes. But, since he said that he
had an electrician rewire the boxes (I think he meant run new wire to the
boxes) instead of just running new ground wires, I am assuming that the
electrician would have noticed if the metal boxes were already grounded. Of
course, I don't know for sure, but that's my guess.
If I saw a separate wire pulled to an outlet box I'd be uneasy about where
it went and whether it really tied into the proper place. (In fact I have
seen that and I was uneasy because some kid did it in my old house and then
put up two different ceilings that made it very hard to trace back. In that
case the ground wire did NOT go back to the panel, but to a clamp on a cold
water pipe. While the outlet appeared koshed with an outlet tested, a
replumbing job with plastic pipe could have ended up with an open ground.)
I'm with Pyped and several other posters who advised that running new NM was
the was to go.
I'd bet a competent home inspector would red flag a ground wire going to
places unknown, especially if it ran under sheetrock or stapled ceiling
tiles or was in some other way untraceable visually.
To be sure it was tied into the panel you'd have to hire an electrican to
trace it with a fox and hound. I am surprised the NEC allows a separate
ground to be run outside the main cable sheath or conduit. If it runs
somewhere other than along the main cable or conduit, the chance of someone
disconnecting it at some future time because it seemed unrelated to the
110VAC wiring is another risk.
GFCIs or new NM would certainly be the preferred way to do things, and I'd
rate those solutions as two or three times as good as a new ground wire,
especially if it didn't at least run along the old wire so that it was
obvious it was related to that old, ungrounded cable.
On a stem wall house...
I have seen this done by running a 4ga "bus" from the (service
entrance/main) panel into the crawl space and pushing 12ga wires up to
each receptacle, bugged to the #4. If you drive a rod at the far end
of this #4 it becomes a grounding electrode conductor and does not
need physical protection. It is also specifically allowed as a point
you can attach a grounding conductor to.
But stupid. And that's why they outlawed the practice. The wire went off
to parts unknown (in my case) and some small amount of current leakage
apparently caused galvanic corrosion to occur where it was clamped to the
waterpipe. It caused a pinhole leaked to develop. All tucked away behind a
stapled ceiling and hard to find without making a hell of a mess. I would
not even had known about it until I took the ceiling down (revealing all
sorts of other nasty surprises). I am sure the previous owner installed
that stapled up ceiling to keep those sorts of issues from the eyes of a
good home inspector.
It was also far enough away from the service entrance that a replacement of
a section of copper with plastic where it entered the house would have
broken the connection to ground.
In my mind, those are two good reasons why they changed the code and why
such connections should be removed and done according to modern rules
whenever they are discovered even if they are still grandfathered.
As for the OP, what was legal in the 70's is moot.
On Saturday, October 11, 2014 10:00:19 AM UTC-4, Robert Green wrote:
*Actually the 2014 code does still permit the connection to the waterpipe.
Article 250.130(C)(1) states that is is permitted "At any accessible point
on the grounding electrode system as described in 250.50". The waterpipe
is part of the grounding electrode system. The water meter and water heate
r bonding jumpers would have to be in place and the clamp would need to be
approved for the type of metal piping.
That is what I think happened in your case. The disimilar metals of the gr
ound clamp (Brass) attached to a steel pipe acted as a battery. Just like
a water heater. The clamp should not have been buried in a finished ceilin
g. The ground wire should have been run over to the water meter location w
here it would have been accessible and could have been clamped to the water
pipe or the grounding electrode conductor.
On Saturday, October 11, 2014 1:42:27 PM UTC-4, John G wrote:
. Article 250.130(C)(1) states that is is permitted "At any accessible poi
nt on the grounding electrode system as described in 250.50". The waterpip
e is part of the grounding electrode system. The water meter and water hea
ter bonding jumpers would have to be in place and the clamp would need to b
e approved for the type of metal piping.
ground clamp (Brass) attached to a steel pipe acted as a battery. Just lik
e a water heater. The clamp should not have been buried in a finished ceil
ing. The ground wire should have been run over to the water meter location
where it would have been accessible and could have been clamped to the wat
er pipe or the grounding electrode conductor.
My understanding is that the water pipe is NOT considered part of the groun
ding electrode system, only something that needs to be bonded *to* the grou
nding electrode system, so relying on a metal pipe for a ground for a previ
ously ungrounded receptacle is no longer allowed, as others have already st
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