Equivalent diameter of screen/sheath and armour

Equivalent diameter between screen/sheath and armour. It becomes the equivalent diameter between screen and sheath when no armour is present.

Symbol
$d_e$
Unit
mm
Formulae
$\sqrt{\frac{{d_s}^2+{d_{ar}}^2}{2}}$single-core cable or cable with common sheath
$\frac{d_s}{2}+\frac{d_{ar}}{2}$cable with separate sheaths or separate screen and no sheath
$d_s$no armour
$d_{ar}$amour but no screen and no sheath