  We study the thermal transport through a Majorana island connected to
multiple external quantum wires. In the presence of a large charging energy, we
find that the Wiedemann-Franz law is nontrivially violated at low temperature,
contrarily to what happens for the overscreened Kondo effect and for
nontopological junctions. For three wires, we find that the Lorenz ratio is
rescaled by a universal factor 2/3 and we show that this behavior is due to the
presence of localized Majorana modes on the island.
