  We address the question of transport of heat, in out-of-equilibrium systems.
The experimental set-up consists in two coupled granular gas Non-Equilibrium
Steady State (NESS) heat baths, in which Brownian-like rotors are imbedded.
These rotors are electro-mechanically coupled thanks to DC micro-motors,
through a resistor $R$, such that energy flows between them. The average flux
depends linearly in the difference of the baths' temperature. Varying $R$
allows to extrapolate in the non-dissipative coupling limit ($R\rightarrow0$).
We show that, in this limit, the heat flux obeys the Fluctuation Theorem, in a
form proposed by Jarzynski and W\'ojcik in $2004$ for the fluctuations of the
flux between finite size equilibrium heat baths.
