5 Jan 91
(ohms), calculated in step 5 above
Header cable/wire resistance (ohms)
Structure-to-earth resistance (ohms).
Backfill column-to-earth resistance (RA)
RA = 0.47 ohm
A deep anode groundbed is defined as one where the
top of the backfill column is at least 50 ft below
the surface of the earth. Actual depth will vary,
depending on subsurface geology and the distance
over which the current is expected to spread. In
this example, 65 ft was selected as the depth to
the top of the coke breeze column. The anodes can
be supplied through a single or dual feed. Dual
feed is preferred to reduce both the resistance of
the circuit and the chance of a failure due to a
No. 4 AWG cable has been chosen.
have been calculated based on the following
illustrated in the deep groundbed
example shown in figure 2-7.