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where RS is the coating resistance in ohm-square feet and
A is the total surface area. If the structure surface is
Calculate required rectifier voltage and current.
The required rectifier voltage (VREC and maximum current
rating should include at least an extra 20 percent to allow
for variations in calculations from actual conditions and
for changes in the system over the system's life.
VREC = (I) (RT) (1.2)
where I is the total current required and RT is the total
circuit resistance as calculated above.
IREC = (I) (1.2)
where I is the total current required and IREC is the
minimum current rating for a rectifier for this particular
Select a rectifier with DC voltage and current capacity of
a slightly larger size (as calculated above) from the
cathodic protection rectifier manufacturer's published
Prepare life cycle cost analysis.
The life cycle cost analysis should be prepared according
to the guidelines given in TM 5-802-1 (reference 9).
Another source of information on performing life cycle cost
analyses is NACE RP-02-72 (reference 21). The choice of a
particular anode type and configuration for design
calculation is somewhat arbitrary.
The economics may
dictate switching to a different design configuration and
repeating the applicable design steps.
Prepare plans and specifications.
Prepare plans that show the protected structure, locations
of anodes, rectifier, test stations, and power source, wire
routing, and details of wire-to-structure connections,
potential survey test points in paved areas, and other
pertinent information. Prepare a one-line diagram to show
the entire system including wire sizes, anode type(s),
power circuit, power circuit protection, and source of