To design a system with durAnodes the current spread and output are particularly important.

The output is depending on the impressed voltage and resistivity of the surrounding electrolyte and is shown in the specification sheet.

Normally the necessary current density of the reinforcement is 5-20mA/m2 steel surface. However, it is not sufficient to pump out the necessary current. The current must be distributed according to the need. So the current spread must be considered.

In principle most of the current will flow from the anode to the closest rebar. In thin slabs where the durAnode must be short only the rebars around the anode will be fully protected. If the current output is increased the nearest rebars will be over protected but the spreading will not be much wider.

In thick slabs where long anodes are used the current can pass by the closest rebars flowing in the un-reinforced cross section. A general rule is that the current can reach rebars at a distance of at least 2-3 times the length of the active part of the anode.

Often columns have corrosion at the top and/or around ground level. With durAnodes the protection can be limited to these exposed and corroding areas.

At ground level it is very likely that the current will spread to the buried part of the column. To obtain sufficient current the number of the durAnodes can be increased at this level.

In heavily reinforced columns two or more lines of durAnodes can be installed to ensure good current spread and sufficient current density to protect all the reinforcement. The anodes in the lines can also be displaced to improve the current output and spread.