PS Magazine - TB 43-PS-725
PS, The Preventative Maintenance Monthly
ISSUE 725
APRIL 2013
50
PS 725
APR 13
51
PS 725
Rods In a Hole
Before you drive, dig a hole at least 12
inches deep and 36 inches across. Then drive
the rod into the hole until the rod’s top is
below ground level. Far too many ground
rods are left sticking above the ground, where
they can be a safety hazard.
Drive the rod in the center of the hole.
Drive it straight. If the soil won’t permit the
rod to go in straight, drive it in at an angle,
but no more than 45 degrees from vertical.
It’s good practice to drive the ground rod down into the water table. The soil
there has less resistance to electrical current. That’s how to get a dependable earth
ground. If you can, locate your equipment near an oasis or subterranean water.
Use a sectional ground rod. Add extensions to reach deeper into the soil until
you can no longer drive the rod. When adding extensions, make sure each section
is tightly connected to the next one. If they’re not tight when you drive in the rod,
you’ll damage the coupling sleeve threads.
Don’t hit the threaded end of the rod with
the hammer. That damages the threads, too.
Instead, screw a driving bolt on the top section.
Make sure it’s tight.Aloose bolt will break off,
or damage the threads.
If you have a slide hammer, NSN 5120-01-
013-1676, use it when installing a sectional
ground rod. A slide hammer makes it easier to
drive rods, and easier to get them out, too.
Try to reach the water table with a single ground rod or one with extensions. If
you can’t, use multiple grounds. Also, use a salt-and-water mixture. The salt and
water make the soil more conductive. See “Soil Preparation” on page 52 for details.
If three rods are used, drive them in a triangular pattern. If four or more rods are
used, put them in a straight line or a star pattern. When using multiple rods, always
connect all the rods together with ground wires or cables. Connect the ±nal rod to
the equipment to be grounded.
If you can’t drive a ground rod more than 4 feet deep, bury the rod horizontally
1
1
/
2
feet deep. Then add a salt-and-water mixture before back±lling the hole.
Before You Drive a Ground Rod
Give your ground rod a
thorough cleaning. Grease,
oil, tar, paint and corrosion
on the rod make it a poor
conductor.
Often
a
sledgehammer
is used to drive in the rod.
The
hammer
striking
the
rod
creates
²ying
metal
fragments. So, wear safety
gloves and goggles to protect
your hands and eyes.
Ground Rods: How Far Apart?
If you drive in multiple ground rods, give them lots of space to get a
good earth ground. Separate the rods by a distance of at least two times
the depth of the rod. In other words, if you’re using 8-ft rods, space them
at least 16 feet apart. Space 10-ft rods at least 20 feet apart.
Grounding…
Safety
in the
Desert Sands
Wear safety
goggles and
gloves
Drive
ground
rod into
hole
Driving
bolt
protects
rod’s
threads
that means you’ll have
to put in
extra
time and
effort to get a solid earth
ground in the desert.
a good ground is
a must to
prevent
electrical shock to
you and damage to
your equipment.
loose,
dry sand
is a
poor
conductor.
725 50-51.indd
1-2
3/6/13
11:37 AM
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