  A simple and direct, based on the equations of motion, derivation of the
variational principle and effective actions for a spherical charged dust shell
in general relativity is offered. This principle is based on the relativistic
version of the D{\AE}Alembert principle of virtual displacements and leads to
the effective actions for the shell, which describe the shell from the point of
view of the exterior or interior stationary observers. Herewith, sides of the
shell are considered independently, in the coordinates of the interior or
exterior region of the shell. Canonical variables for a charged dust shell are
built. It is shown that the conditions of isometry of the sides of the shell
lead to the Hamiltonian constraint on these interior and exterior dynamical
systems. Special cases of the \^ohollow\"o and \^oscreening\"o shells are
briefly considered, as well as a family of the concentric charged dust shells.
