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ETL 1110-9-10(FR)
5 Jan 91
current requirement test has been performed, as a check
on assumptions made. Current density may be estimated
from information given in table 3-1.
d.
Select anode type.
Ceramic anodes are made in a variety of shapes, such as,
wires, rods, tubes, strips, disks, and mesh.
The 0.062-in. diameter anode wire has a 20-year life at a
maximum current rating of 115 mA per linear ft in fresh
water, 285 mA in salt water, and 170 mA in brackish
water. Wire anodes are well suited for applications in
water tanks. They are generally not used underground.
Ceramic rod anodes are manufactured bare for aqueous
environments and prepackaged for installation in soil.
Ceramic rod anodes are produced in diameters of 1/8 in.,
1/4 in., 3/8 in. and in. and in standard lengths of 4,
6, and 8 ft, although almost any length can be custom
fabricated with self-healing screw connections for field
assembly to the desired length, or with permanent,
factory-molded, cable-to-anode connections. For
underground applications, rods are frequently packaged in
2- or 3-in. diameter steel tubes filled with a high
carbon, low resistivity coke breeze. Their small size
and high current capacity make rods particularly well
suited for both underground shallow and deep anode
systems. For marine applications, the rod anode is often
encased in a perforated PVC package that provides
mechanical protection and prevents the possibility of the
anode contacting the protected structure. They are used
in a similar manner as high silicon cast iron and
graphite anodes.
For long ceramic anode wires and rods, the voltage drop
in the titanium substrate must be considered. While
titanium is a relatively good metallic conductor, its
resistance is approximately 33 times that of copper. The
maximum length for solid titanium wire and rod anode
applications to assure that uniform discharge of current
is achieved in several different environments is provided
below:
Maximum Anode Length From Connection Point
Solid Titanium Anodes
Anode Diameter
0.062 in. 0.125 in. 0.250 in.
7
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