Bud-- wrote:

Using the electric hammer you drive the first rod into the earth at
least the distance away from the house that the footer is under the
ground. If the footer is eight feet down then the rod should be eight
feet out from the foundation wall.


Why not drive next to the building since you are using multiple rods and
will pass the footing? That would reduce the conductor length and put it
all in a more protected area. If away from the building can you use
shallow burried #4? If aiming for 5 ohms should grounding electrode
conductor be full size as for water pipe?

If a single rod is driven next to the building, as is common practice,
only about half of the rod faces dirt. If the foundation was wood
(insulator) I would think the ground resistance would be double that for
a rod in the middle of the yard. For concrete walls is there conduction
along the wall that lowers the resistance? Seen any information along
these lines?

For a single rod I would think driving through the basement floor
(misisng the footing) would give a lower resistance. The rod has earth
all the way around, is not in frozen ground part of the year and is
lower in the earth and likely nearer wetter soil or ground water.
Probably should be 10' to put the required 8' in contact with the earth.

Great description of coupled rods and installation.

bud--

I've always driven them away from the footer and only part of that is
electrical. The backfill near the footer often contains a lot of trash
that will block or distort the driven rod.

Even at lower resistance the EGC need not be larger than Number two
according to the papers that I read so many years ago.

As for driving through the basement floor that works during construction
but after that it is usually too difficult to drive them in a basement
with ceilings less than twelve feet.
--
Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
We're just working men and woman most remarkable like you.