DIYbanter - View Single Post - Grounding question -- ping gfretwell

Doug Miller[_4_]

wrote in
:

On Mon, 25 Jul 2016 12:11:14 -0000 (UTC), Doug Miller
wrote:

My house, built in 1962, has one grounding electrode: the metal
plumbing system. Doesn't meet Code now, but I'm pretty sure it
did in 1962. The grounding electrode conductor is attached to
the plumbing directly inside the point at which it enters from
the outside -- pretty much completely on the opposite side of
the house from the electrical service entrance.

In conjunction with a renovation project completely unrelated to
the electrical system, I'm going to have to temporarily
disconnect and possibly relocate the grounding electrode
conductor.

I know that current Code:
(a) does not permit the metal water plumbing system to be the
*only* grounding electrode;

True

(b) does not require the metal water plumbing to be a grounding
electrode *at all*;

Not true, water pipe shall be bonded

Bonded to the grounding electrode, right, I know that. Maybe I'm not using the correct
terminology here.

(c) requires that *if* it is used as a grounding electrode, the
conductor must be attached within 5 feet of the point of
entrance to the building; and

Entrance of the water pipe

Right, that's what I meant, sorry for not being specific.

(d) does require it to be bonded to *other* grounding
electrode(s).

All available electrodes shall be used

Yep.

Here's what I propose to do:

(1) Sink a 10-foot grounding rod directly outside the service
entrance, and connect an appropriately-sized grounding conductor
(AWG 4 for 200A service?) to it and the service entrance panel.
That will give me a grounding electrode other than the water
pipes.

OK

(2) Cut the existing grounding electrode conductor short, and
bond it to the water pipes at the most convenient location,
about ten feet from the service entrance -- which is some forty
feet from the point at which the water pipe enters the building.

Just leave it the way it is

I *can't*. I have to disconnect and move it, at least temporarily, for the other project -- it's in
the way. And that's going to be a pain in the neck: it's inside EMT. I was hoping to be able to
avoid reinstalling it in the same manner.

Am I correct in believing that this meets current Code?

Here's my reasoning: The connection to the water pipe is much
more than the five-foot minimum required if the water pipe is
used as a grounding electrode -- but because the system will be
grounded to a grounding rod, *that* is the grounding electrode,
*not* the water pipes, which are merely *bonded* to the
grounding electrode.

The 5' refers to the water pipe, not the distance from the
electrical service entrance. They are just minimizing the chance
that a piece of plastic will end up in that metal pipe.

Understood.

If this
is still the good old copper pipe all the way to the street, it
will still be your best electrode. The GEC to a rod only has to
be 6 gauge, no matter how big the service is, just because that
is about all it will end up grounding anyway. The water pipe,
being the better electrode still needs a full sized 250.66
conductor (#4 for typical 200a)

And that *must* be connected within 5' of where the water pipe enters the building,
regardless of the presence of any other grounding electrodes in the system?