Ratio of heat dissipation coefficients

The ratio of heat dissipation coefficients for group of cables in air is according to IEC 60287-2-2 Ed.1.0

Symbol
$h_{lg}$
Formulae
$1.41$2 cables or ducts, side by side, $e_{hor}/Do_d$ < 0.5
$1.65$3 cables or ducts, side by side, $e_{hor}/Do_d$ < 0.75
$1.2$2 trefoils, side by side, $e_{hor}/Do_d$ < 1
$1.25$3 trefoils, side by side, $e_{hor}/Do_d$ < 1.5
$1.35$2 cables or ducts, one above the other, $e_{ver}/Do_d$ < 0.5
$\frac{1.085}{\left(\frac{e_{ver}}{Do_{d}}\right)^{0.128}}$2 cables or ducts, one above the other, $e_{ver}/Do_d$ < 1.89
$1.57$3 cables or ducts, one above the other, $e_{ver}/Do_d$ < 0.5
$\frac{1.19}{\left(\frac{e_{ver}}{Do_{d}}\right)^{0.135}}$3 cables or ducts, one above the other, $e_{ver}/Do_d$ < 3.62
$1.39$2 trefoils, one above the other, $e_{ver}/Do_d$ < 0.5
$\frac{1.106}{\left(\frac{e_{ver}}{Do_{d}}\right)^{0.078}}$2 trefoils, one above the other, $e_{ver}/Do_d$ < 3.63
$1.23$near to a surface, $e_{wall}/Do_d$ < 0.5
$1$otherwise
Related
$Do_{d}$
$e_{hor}$
$e_{ver}$
$e_{wall}$
Image
IEC standard 60287-2-2 Ed. 1.0 (1995) Table 1