Factor for cross-bonded earthing

This is the multiplication factor for cross-bonded earthing.

When the lengths of the three cable sections are not known, $p_{cb}$ should be set to 1, and $q_{cb}$ to 1.2, giving a value for $f_{cb}$ slightly below 0.004.

For two single core cross-bonded cables, which is not covered in the IEC standard, $f_{cb}$ is set to 0.004.

When all the lengths of the three cable sections are identical, $f_{cb}$ becomes zero.

Symbol
$f_{cb}$
Formulae
$\frac{p_{cb}^{2} - p_{cb} q_{cb} - p_{cb} + q_{cb}^{2} - q_{cb} + 1}{\left(p_{cb} + q_{cb} + 1\right)^{2}}$three-phase systems
$\frac{p_{cb}^{2} - p_{cb} + 1}{\left(p_{cb} + 1\right)^{2}}$two-phase systems
$0$single-phase system
Related
$a_{S1}$