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Total Solution to Earthing & Lightning Protection |
9AKK106354A3360
7/3
7
Effect of electrode diameter
on resistance
100%
80%
60%
40%
0%
1/2” 3/4” 1” 11/4” 11/2” 13/4” 2”
Thread and shank diameters
Confusion often arises between thread and shank diameters
for threaded rods.
The thread rolling process, used by quality rod manufacturers,
raises the surface of the rod so that thread diameter (B) is
greater than shank diameter (A) (see drawing).
All threads are Unified National Coarse (UNC-2A).
A
B
Rod
Diameter
Diameter of rod
One common misconception is that the diameter of the rod
has a drastic effect on lowering earth resistance. This is
not true! As the graph shows, you only lower the resistance
value by 9.5% by doubling the diameter of the rod (which
means increasing the weight and the cost of the rod by
approximately 400%).
Thus the rationale is:
Use the most economical rod that soil
conditions will allow you to drive. This is one of the ways to
ensure that you don’t waste money on over-dimensioned rods.