  Thermal conductance has emerged as a powerful probe of topological order in
the quantum Hall effect and beyond. The interpretation of experiments crucially
depends on the ratio of the sample size and the equilibration length, on which
energy exchange among contra-propagating chiral modes becomes significant. We
show that at low temperatures the equilibration length diverges as $1/T^2$ for
almost all Abelian and non-Abelian topological orders. A faster $1/T^4$
divergence is present on the edges of the non-Abelian PH-Pfaffian and
negative-flux Read-Rezayi liquids. We address experimental consequences of the
$1/T^2$ and $1/T^4$ laws in a sample, shorter than the equilibration length.
