Ground rod backfill installation, Instruction sheet 2 – ERICO GEM User Manual
Page 2
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GROUND ROD BACKFILL INSTALLATION
1. Auger a 3-inch (7.5 cm) or larger diameter hole to
a depth of 6 inches (15 cm) shorter than the length
of the ground rod.
2. Place ground rod into augered hole and drive
one foot (if possible) into bottom of the hole.
The top of the ground rod will be approximately
6 inches (15 cm) below grade. At this time, make
any connections to ground rod using CADWELD
®
connections. (See Note 1)
3. Premix GEM into a slurry form. Use 1.5 to 2 gallons
(5.7 to 7.6 liters) of clean-potable water per pail of GEM.
The installation of GEM in a dry state is acceptable for
vertical ground rod applications.
4. Pour the appropriate amount of GEM (see table)
around the ground rod. To ensure the GEM material
completely fills the hole, tamp around the ground
rod with a pole. Wait 30 minutes to 1 hour before
filling the hole with soil backfill.
5. Fill remainder of augered hole with soil removed
during augering. For various augered-hole
diameters and depths, see the table below.
Note 1: 4 inches (10 cm) of insulating material should be
applied to the conductors and ground rods exiting
the GEM, starting 2 inches (5 cm) inside the GEM.
Note 2: Excess standing water must be removed from
the hole.
* 8-foot (2.4 m) minimum rod length required to be in contact with the soil (or GEM), per NEC
®
250-83-C.
Note: To mix GEM into a slurry form, use a standard cement mixer or mix in the GEM pail, a mixing box,
wheelbarrow, etc. Use 1.5 to 2 gallons (5.7 to 7.6 liters) of clean-potable water per pail of GEM.
Do not mix GEM with salt water.
INSTRUCTION SHEET
2
diameter
augered hole
6” shorter than
Ground Rod
15 cm
6”
15 cm
GEM packed
around
Ground Rod
6”
15 cm
Ground Rod
12”
30 cm
Soil Backfill
Estimated pail of GEM for backfilling around ground rods to a density of 63.5 lb/cu ft
3
Depth of hole (feet)*
Dia. of hole
(inches / cm)
6’
1.8 m
7’
2.1 m
8’
2.4 m
9’
2.8 m
17’
5.2 m
19’
5.8 m
20’
6.1 m
3
7.5
2
2
2
2
4
4
4
4
10.0
2
3
3
3
6
7
7
5
12.7
3
4
4
5
9
10
10
6
15.2
5
5
6
7
13
14
15
7
17.8
6
7
8
9
17
19
20
8
20.3
8
9
11
12
22
25
26
9
22.9
10
12
13
15
28
31
32
10
25.4
12
14
16
18
34
38
40