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0_Qed said:
Readership,
Is an 'almost' horizontally driven 8' 5/8" rnd ground rod as effective
as a vertically driven ground rod ???
Clay/Shale at about 4' depth ,
thus the query about 'near' horizontal.
Ed
Dwight gives :
vertical rod Resistance =(rho/2*pi*L)(ln(4L/a)-1)
where rho is the soil resistivity L is the rod length and a is its radius
horizontal rod: Resistance =(rho/4*pi*L){ln(4L/a)+ln(4L/s) -2 +s/2L -smaller
terms)
where the length is 2L depth s/2 and the rest as above
for L=3m a=0.01m and s =0.3m
R vert/R horiz =1.07/1.24 =86%
This is assuming uniform earth which you don't have. Use a longer horizontal
rod (say by a factor of at least 2 and 3 would be better); or a grid such as
a 3 point horizontal star with arms of length L
(this gives, for the same L, less than 60% of the resistance of a single
vertical rod.)
Hey, a star or grid uses more conductor but it is still cheaper than trying
to get a good ground with a vertical rod.