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ETL 1110-9-10(FR)
5 Jan 91
From grade to top of backfill column 65 ft
From top of backfill column to
top anode
10 ft
From grade to bottom of backfill
column
176 ft
From bottom anode to bottom of
backfill column
10 ft
From anode hole to rectifier 2
cables at 125 ft
250 ft
From top of anode assembly to
bottom of anode assembly
91 ft
Total cable length from top anode
feed to rectifier 125 ft +
65 ft + 10 ft=
200 ft
Total cable length from bottom
anode feed to rectifier
125 ft + 176 ft - 10 ft =
291 ft
Calculate
top
cable
resistance
(RWT)
from
equation 1-15:
LWT RMFT
RWT '
1000 ft
Where:
LWT
=
200 ft (Cable
length
from
previous
calculation)
RMFT
=
0.254 ohm (Resistance per 1000 lin ft
of No. 4 AWG cable which has been
selected for installation.
These
resistance values can be found in
table 3-6).
RWT
=
200 ft x 0.254 ohm
= 0.051 ohm
1000 ft
Calculate bottom
cable
resistance
(RWB)
from
equation 1-15:
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