Application Note

8 Fluke Corporation Checking ground electrode impedance for commercial, industrial and residental buildings.
Summary of Ground Electrode Test Methods
Advantages Drawbacks
Fall-of-Potential • Widely accepted
• When you see the character
-
istic curve you know you’ve
got a good measurement.
• You have to disconnect the
ground
• The stakes may not be easy
to drive
• There may not be space
around the ground electrode
to drive the stakes
Selective Method • Don’t have to disconnect
electrode
• Widely accepted
• When you see the character
-
istic curve you know you’ve
got a good measurement.
• The stakes may not be easy
to drive
• There may not be space
around the ground electrode
to drive the stakes
Stakeless Method • Convenience • Assumes a low-impedance
parallel path
• Possible to get very low
readings by mistakenly
measuring on a hard-wired
loop
Two-pole Method • Convenience • Impossible to judge the
integrity of the “auxiliary
electrode.”
• Can’t be sure you are outside
the area of influence
Table for the Tagg Slope Technique
(for 2 decimal places)
0.40 64.3
0.41 64.2
0.42 64.0
0.43 63.9
0.44 63.7
0.45 63.6
0.46 63.5
0.47 63.3
0.48 63.2
0.49 63.0
0.50 62.9
0.51 62.7
0.52 62.6
0.53 62.4
0.54 62.3
0.55 62.1
0.56 62.0
0.57 61.8
0.58 61.7
0.59 61.5
0.60 61.4
0.61 61.2
0.62 61.0
0.63 60.9
0.64 60.7
0.65 60.6
0.66 60.4
0.67 60.2
0.68 60.1
0.69 59.9
0.70 59.7
0.71 59.6
0.72 59.4
0.73 59.2
0.74 59.1
0.75 58.9
0.76 58.7
0.77 58.5
0.78 58.4
0.79 58.2
0.80 58.0
0.81 57.9
0.82 57.7
0.83 57.5
0.84 57.3
0.85 57.1
0.86 56.9
0.87 56.7
0.88 56.6
0.89 56.4
0.90 56.2
0.91 56.0
0.92 55.8
0.93 55.6
0.94 55.4
0.95 55.2
0.96 55.0
0.97 54.8
0.98 54.6
0.99 54.4
1.00 54.2
1.01 53.9
1.02 53.7
1.03 53.5
1.04 53.3
1.05 53.1
1.06 52.8
1.07 52.6
1.08 52.4
1.09 52.2
1.10 51.9
1.11 51.7
1.12 51.4
1.13 51.2
1.14 50.9
1.15 50.7
1.16 50.4
1.17 50.2
1.18 49.9
1.19 49.7
1.20 49.4
1.21 49.1
1.22 48.8
1.23 48.6
1.24 48.3
1.25 48.0
1.26 47.7
1.27 47.4
1.28 47.1
1.29 46.8
1.30 46.5
1.31 46.2
1.32 45.8
1.33 45.5
1.34 45.2
1.35 44.8
1.36 44.5
1.37 44.1
1.38 43.8
1.39 43.4
1.40 43.1
1.41 42.7
1.42 42.3
1.43 41.8
1.44 41.4
1.45 41.0
1.46 40.6
1.47 40.1
1.48 39.7
1.49 39.3
1.50 38.9
1.51 38.4
1.52 37.9
1.53 37.4
1.54 36.9
1.55 36.4
1.56 35.8
1.57 35.2
1.58 34.7
1.59 34.1
µ
P2/C2
%
µ
P2/C2
%
µ
P2/C2
%
µ
P2/C2
%
µ
P2/C2
%
Fluke Corporation
PO Box 9090, Everett, WA USA 98206
Fluke Europe B.V.
PO Box 1186, 5602 BD
Eindhoven, The Netherlands
For more information call:
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Web access: http://www.fluke.com
©2005-2007 Fluke Corporation. All rights reserved.
Specifications subject to change without notice.
Printed in U.S.A. 3/2007 2550440 A-EN-N Rev C
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