I am installing the electrical service to a new barn and the power co.
has agreed to run a service drop from a nearby pole. The barn will
have 200amp service and I plan on installing the meter base, service
riser, necessary conductors, and service panel myself. A licensed
electrician will inspect the work before I call the power co. for the
I have placed two 1/2" copper clad 8 foot ground rods along the
outside of the barn's sill, about 7+ feet apart. The first rod, which
will be right below the meter base, went into the ground like butter.
I left a couple of inches sticking up and will drive flush with
surface once I install acorn clamp and 4awg copper ground wire.
The 2nd rod, however, was a big pain in the neck. I kept hitting
rocks until I finally found a spot where I could drive it in about 5
feet without too much trouble. The next 2.5 feet, unfortunately, were
awful and now the rod is sticking up about 3 inches and won't budge
any more. The top also has a nice mushroom going from the incredible
pounding it took with the sledge. I'll probably have to cut about a
1/2 inch off the rod to get the clamp on.
I know the NEC requires that all 8 feet of the rods be in the ground.
How big a deal is it that the 2nd rod is 3-4 inches short of that
requirement? Both rods are in fairly moist, loamy clay soil (barn is
at bottom of a mountain and about 120 feet from a creek; year round
moisture is probably assured as little as 1 or 2 feet down).
The service panel will be inside the barn, opposite the meter base
which is on the outside of the barn. Even though the panel will be
bonded to the outside ground rods via the service entry cable, I am
tempted to install a 3rd ground rod inside the barn along the wall
(the barn has a dirt floor for now) and bond it to the ground lug in
the panel. The 3rd ground rod will be at least 6 linear feet from two
other rods (which will put it about 15 feet from the service panel).
Is the installation of a separate ground for the service panel
required in something like a barn? It seems a like a good, safe thing
to do. And too easy a thing to not do it.
Any other suggestions/comments?
bruce at loth dot us