  Ohmic contacts are crucial elements of electron optics that have not received
a clear theoretical description yet. We propose a model of an Ohmic contact as
a piece of metal of the finite capacitance $C$ attached to a quantum Hall edge.
It is shown that charged quantum Hall edge states may have weak coupling to
neutral excitations in an Ohmic contact. Consequently, despite being a
reservoir of neutral excitations, an Ohmic contact is not able to efficiently
equilibrate edge states if its temperature is smaller than $\hbar\Omega_c$,
where $\Omega_c$ is the inverse RC time of the contact. This energy scale for a
floating contact may become as large as the single-electron charging energy
$e^2/ C$.
