5 Jan 91
RT = RN + RW + RC
RN = Groundbed resistance (ohms)
RW = Header cable/wire resistance (ohms)
Groundbed resistance (RN) from step 5.
RN = 2.26 ohms
Header cable/wire resistance (RW) from equation 1-
150 ft (Effective cable length. The loop
circuit makes calculating effective wire
Since current is
discharged from anodes spaced all along the
cable, one-half the total cable length may
resistance. Total cable length = 300 ft.
Effective cable length = (300 ft) = 150
0.254 ohm (This is the resistance per
1000 lin ft of No. 4 AWG cable, which
selected for ease of
150 ft x 0.254 ohm
0.038 ohm; use 0.04 ohm
Since the tanks and piping are essentially bare and
are not electrically isolated, structure-to-earth
resistance may be considered negligible. Therefore
RC = 0.