Galvanic Anode Output Current Calculator
For CP technicians sizing sacrificial or ICCP systems, quickly estimating the actual deliverable current of an anode array before procurement without building a complex electrochemical model.
This tool uses the principle of Ohms law for calculating galvanic anode output current: I = (E_c - E_a) / R applying Ohms law to driving voltage and anode-to-earth resistance. Disclaimer: for preliminary estimation only, not a substitute for review by a qualified/licensed engineer.
Tool
Output Current
How-to
- Enter the protected structure's measured cathode protection potential in volts.
- Enter the installed anode's open-circuit potential in volts.
- Input the combined electrical resistance of the anode bed and cabling in ohms.
- Read the estimated output current in Amperes displayed instantly below the controls.
FAQ
Q: What is the typical driving voltage for magnesium anodes?
A: Magnesium alloys generally provide a driving voltage of 0.7 V to 0.85 V against steel structures, depending on soil resistivity and exact alloy composition.
Q: How does soil resistivity affect anode output current?
A: Soil resistivity directly dictates the anode-to-earth resistance (R) in the denominator of the equation; higher resistivity increases R, which proportionally reduces the delivered output current.
Q: Should I account for cable resistance in the circuit resistance input?
A: Yes, the total circuit resistance (R) must include both the anode-to-soil resistance calculated via methods like Dwight's Equation and the series resistance of all connecting cables and joints.
Q: Is this calculation suitable for final system design?
A: No, this provides a preliminary DC estimate based on pure Ohm's Law; final designs require accounting for polarization effects, coating holidays, and temperature coefficients, verified by a licensed PE.