# Ratio of thermal resistance to ambient

The ratio of thermal resistance to ambient for group of cables in air is quickly converging equation is solved by iteration, starting with a value of $h_{lg}$.

Symbol
$h_{T4}$
Formulae
$h_{lg} \left(\frac{1-k_l}{h_{T4}}+k_l\right)^{0.25}$
Related
Used in
$T_{4iii}$