AEMC 450.100, Руководство пользователя

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Digital Ground Resistance Tester Model 4500
Grounding Nomograph
Ground Rod
Resistance-Ohms
Soil Resistivity
(Ohm-centimeters)
Rod Depth
Feet
Rod Diameter
Inches
R
P
D
DIA
20
30
40
90
50
60
70
80
100
15
10
1
5
2
4
3
5/8
1/4
1/2
3/4
1
1.5
8
7
6
5
4
3
2
10000
15000
100000
50000
40000
30000
20000
3000
500
1000
2000
4000
5000
20
30
100
90
80
70
60
50
40
15
1
2
3
4
5
6
7
8
9
10
K
Figure 8
1. Select required resistance on R scale.
2. Select apparent resistivity on P scale.
3. Lay straightedge on R and P scale, and allow to intersect with K
scale.
4. Mark K scale point.
5. Lay straightedge on K scale point and DIA scale, and allow to intersect
with D scale.
6. Point on D scale will be rod depth required for resistance on R scale.
4.2 Ground Resistance Values
NEC
®
2008 article 250.56 regarding the resistance of rod, pipe and plate
electrodes states that if the rod, pipe, or plate does not have a resistance
of 25 Ω or less to ground shall be augmented by one additional electrode of
any of the types specified by 250.52 (A)(4) through (A)(8). Where multiple
rod, pipe or plate electrodes are installed to meet the requirements of the
section, they shall not be less than 6 feet apart.