Suspicious ground wire...

[Equillibrius]

I've noticed that one of the electrical conduits in our
basement has a solid wire (14-gauge, it looks like) wrapped
around it, and the other end is wrapped around the cold
water pipe at the point where it enters the house. A
do-it-yourself grounding technique made by a previous owner,
perhaps? The conduit itself doesn't have a third ground
wire, the ground terminals on the switch and outlets are
just wired to the metal boxes.

With the exception of the wire running between the conduit
and the water pipe, I'm assuming that the conduit isn't
grounded, because much of the wiring in the basement is
still old "knob and tube" wiring. So now I'm looking at
this makeshift ground connection, saying to myself, "This
CANNOT be safe." I'm not sure what the electrical
regulations say about this kind of thing, but does anyone
know if my suspicions are correct?

 

[Kilowatt]

That is a most unusual situation with knob and tube and conduit in the same
house.

You can run romex in a basement. I wonder why the conduit is there in the
first place?

If it turns out to be unsafe you might just consider fixing it with romex.
It is a much cheaper solution than running conduit.

 

[Equillibrius]

net...

That is a most unusual situation with knob and tube
and conduit in the same house.

You can run romex in a basement. I wonder why the
conduit is there in the first place?

If it turns out to be unsafe you might just
consider fixing it with romex. It is a much
cheaper solution than running conduit.

I guess I forgot some details in my first post.

The conduit in question runs along a brick wall and serves
two fluorescent light fixtures and some receptacles for a
utility desk. I think it was added some time after the
house was built (early 40s), and I'm guessing whoever
installed it didn't want to punch holes in the brick.

 

[Kilowatt]

The conduit can serve as the ground itself without having a green ground
wire in the conduit (if the conduit is bonded at the panel or starting point
for the pipe). You can then bond to the box like you described he has done.
I am guessing if he took the time to bond to the box like you say that the
open wire in question might just be used to keep another pipe from vibrating
or just to tie up something.

The only way to know for sure is try to figure out another reason the wire
is there.

I can think of no reason why anyone would want to try to ground a system the
way you describe.

 

[John Ray]

<snip>

As stated before, the conduit (we're assuming EMT or the like) IS a
grounding conductor IF it originates in a grounded box. Its not uncommon
with a house old enough to have knob and tube to have a few 'generations' of
wiring, since electrical requiements were pretty basic back in those days.
Its also not uncommon for weekend warriors to 'fix' a perceived problem that
does not exist. In other words...disconnect the wire in question and check
for continuity between neutral and ground @ one of the recepticals served by
the conduit... if you have continuity, you are reading the neutral bond @
the panel and you are most likely ok.

john