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ETL 1110-9-10(FR)
5 Jan 91
RMFT
=
0.1183 ohm (Cable resistance per
1000 lin ft [same as above])
RWB
=
205 ft x 0.1183 ohm = 0.024 ohm
1000 ft
These two cables are in parallel, so that total
1
=
1
+
1
RT/B
RWT
RWB
1
=
1
+
1
RT/B
0.014
0.024
1
RT/B
= 71.43 + 41.66 = 113.1
RT/B
= 0.009 ohm
Since current dissipates along the portion of the
cable to which the anodes are connected, the
its total resistance, as was done in example 2-2.
LW RMFT
1
85 x 0.1183 ohm/ft
1
RPOS '
'
x
x
1000 ft
2
1000 ft
2
RPOS = 0.005 ohm
Negative cable resistance:
The rectifier is
placed 25 ft from the connection to the piping,
using No. 4 AWG HMWPE insulated cable. Negative
resistance is calculated from equation 1-15:
LW RMFT
RNEG '
1000 ft
Where:
LW
=
25 ft (Length of cable)
65
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