Design of magnesium anode systems requires a thorough evaluation of the application with consideration of the important variables. Once these variables are measured or assumed, the process typically is divided into the following steps.

**Calculate exposed surface area**- This requires an assumption of coating quality. A high quality coating can provide protection to over 99% of the total surface area. A conservative assumption of coating efficiency is 95%.**Calculate total current requirements**- This requires an assumption of current density. The typical range of current density for steel in common soils is 1 to 3 milliamperes per square foot of exposed surface. A conservative assumption is 2 milliamperes per square foot.**Calculate anode current output**- Using previous discussed formulas, calculate anode output considering the effect of coating, soil resistivity, alloy selection, and anode spacing. Several anode sizes should be evaluated.**Select anode size based on life**- Once anode current outputs have been calculated, the appropriate anode size can be selected by evaluating the projected life. Typical design lives range from 10 to 20 years.**Calculate total anode quantity**- Divide the total current requirement in amperes by the calculated anode output in amperes. The result is the estimated total number of anodes required.**Determine anode location and configuration**- This is primarily based on local site conditions and an even distribution of current from the anodes.

## Courtesy of CP Design Center by MESA Products, Inc. |
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